Lincoln 2006 Town Car Instruction manual

Climate Control System Printable View (966 KB)
Inspection and Verification
1. Verify the customer's concern by operating the climate control system to duplicate the condition.
2. Inspect to determine if one of the following mechanical or electrical concerns apply:
Visual Inspection Chart
SECTION 412-00: Climate Control System — General Information and Diagnostics 2006 Town Car Workshop Manual
DIAGNOSIS AND TESTING
Procedure revision date: 08/12/2009
Special Tool(s)
A/C Flush Adapter Kit
219-00074 or equivalent
Flex Probe Kit
300-NUD105-R025DE or equivalent
Fluke 77-IV Digital Multimeter
FLU77-4 or equivalent
Pressure Test Kit
014-R1072 or equivalent
R-134a Manifold Gauge Set
176-R032A or equivalent
Refrigerant Leak Detector
216-00001 or equivalent
Set, A/C Fittings
412-DS028 (014-00333, D93L-19703-B) or equivalent
Test Light
SGT27000 or equivalent 250 mA incandescent bulb test lamp
Vacuum Pump Kit
416-D002 (D95L-7559-A) or equivalent
Worldwide Diagnostic System (WDS)
Vehicle Communication Module (VCM) with appropriate adapters, or
equivalent diagnostic tool
Mechanical Electrical

Loose, missing or damaged A/C compressor drive belt
 Loose or disconnected A/C clutch
 Broken or binding door/actuator
 Broken or leaking refrigerant lines
 Obstructed in-vehicle temperature sensor
 Disconnected in-vehicle temperature aspirator hose
 Central junction box (CJB) fuse:
 9 (7.5A)
 15 (10A)
 27 (10A)
 31 (10A)
 Battery junction box (BJB) fuse:
 101 (40A)
 11 (15A)
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3. As pinpoint tests and measurements are being carried out, be sure to inspect for any disconnected, loose-fitting or incorrectly installed component, module and in-line electrical
connectors and pins.
4. If the inspection reveals obvious concern(s) that can be readily identified, repair as required.
5. If the concern remains after the inspection, connect the diagnostic tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from
the diagnostic tool menu. If the vehicle selection cannot be entered:
 check that the program card is correctly installed.
 check the connections to the vehicle.
 check the ignition switch position.
If the diagnostic tool still does not allow the vehicle selection to be entered, refer to the diagnostic tool manual.
6. Carry out the DATA LINK DIAGNOSTIC TEST using the diagnostic tool. If the diagnostic tool responds with:
 SCP+, SCP-, CAN or UBP circuits fault = ALL MODULE NO RESPONSE/NOT EQUIPPED, go to Communication System Diagnostics in Section 418-00 to diagnose the
network concern.
 If the powertrain control module (PCM) is not listed for a communication concern, turn the A/C controls to OFF and execute the self-test diagnostics for the PCM.
 If the EATC module is not listed for a communication concern, execute the self-test diagnostics for the EATC module.
7. If any PCM or EATC DTCs are retrieved, and are related to the concern, go to the Powertrain Control Module Diagnostic Trouble Code (DTC) Index or the Electronic Automatic
Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) Index to continue the diagnostics.
8. If no DTCs related to the concern are retrieved, go to the Symptom Chart to continue the diagnostics.
9. If the Electronic Automatic Temperature Control module cannot be accessed by the diagnostic tool, GO to Pinpoint Test H.
Electronic Automatic Temperature Control Module Self-Test
 The EATC module self-test will not detect concerns associated with data link messages like engine coolant temperature or vehicle speed signals. A diagnostic tool must be used to
retrieve these concerns.
 The EATC module self-test will detect concerns in the system control functions and will display hard diagnostic trouble codes (DTCs). Hard DTC's identify faults which are present
during the self- test. The vehicle interior/ambient temperature should be between 4-32°C (40-90°F) when carrying out the self-test. If the temperatures are not within the specified
ranges, false temperature sensor DTCs will be displayed.
 The self-test can be initiated at any time. Normal operation of the system stops when the self-test is activated.
 To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTO button within 2 seconds. The display will show the fan speed indicator illuminating
from low to high. The test may run as long as 30 seconds. Record all DTCs displayed.
 If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given.
 If a condition exists but no DTCs appear during the self-test, refer to the Symptom Chart Condition: The EATC System Is Inoperative, Intermittent or Incorrect Operation.
 To exit the self-test and clear all DTCs, press the FRONT DEFROST button. The EATC control assembly will then turn OFF (display blank) and all DTCs will be cleared.
 Always exit the self-test before powering the system down (system turned OFF).
Electronic Automatic Temperature Control Module — Display Continuous Codes
 This function will display continuous (intermittent) codes and hard faults that occur during normal operation.
 To display continuous codes, press the OFF and FLOOR buttons simultaneously and then release and within 2 seconds press the RECIRC button.
 To exit the display of continuous codes, press the FRONT DEFROST button. This will exit and clear all DTCs. Press any button except DEFROST to exit without clearing DTCs set
before the last ignition cycle.
 Always exit continuous codes display before powering the system down (system turned off).
 Continuous DTCs are saved only after an ignition cycle.
 Continuous DTCs will be deleted after 80 ignition switch ON cycles after the intermittent condition occurs.
Electronic Automatic Temperature Control (EATC) Module Cold Boot Process
The purpose of the cold boot process is to allow the EATC module to re-initialize and calibrate the actuators. To carry out the cold boot process, follow the steps below.
1. Clear the DTCs.
2. Turn the ignition switch to the OFF position.
3. Disconnect the EATC module electrical connectors.
4. Inspect the module connectors for:
 corrosion.
 pushed-out pins.
 incorrectly seated connector.
5. Wait one minute.
6. Connect the EATC module electrical connectors.
7. Turn the ignition switch to the ON position.
8. Select any position except OFF on the EATC module.
The EATC module will now initialize and calibrate the actuators. Calibration of the actuators will take approximately 30 seconds.
Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index
 21 (15A)
 Blower motor inoperative
 A/C compressor inoperative
 Circuitry open/shorted

Disconnected electrical connectors
 Cooling fan inoperative
DTC Description Action
P1460 WOT A/C cutout internal driver malfunction REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
P1469 Low A/C cycling period REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
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Rear Redundant Control Module (RRCM) Diagnostic Trouble Code (DTC) Index
ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX
Symptom Chart
P1474 Low speed fan internal driver failure REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
P1479 High speed fan internal driver failure REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
P1464 A/C demand out of self-test range REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
DTC Description Action
B113D Rear climate control switch stuck INSTALL a new rear climate control switch. TEST the system for normal operation.
B113E Rear climate control switch circuit short to ground GO to Pinpoint Test O.
B113F Rear climate control switch circuit short to battery GO to Pinpoint Test P.
U1178 SCP (J1850) Invalid or missing data for climate control REFER to Section 418-00 to diagnose a network concern.
DTC
EATC Self-
Test Faults Description Action to take
B2266 2266 Driver side blend door failure or short GO to Pinpoint Test A.
B2267 2267 Passenger side blend door failure or
short
GO to Pinpoint Test A.
B1251 1251 In-vehicle temperature sensor open
circuit
GO to Pinpoint Test B.
B1253 1253 In-vehicle temperature sensor short to
ground
GO to Pinpoint Test B.
B1255 1255 Ambient temperature sensor open
circuit
GO to Pinpoint Test C.
B1257 1257 Ambient temperature sensor short to
ground
GO to Pinpoint Test C.
B1259 1259 A/C solar radiation sensor open circuit GO to Pinpoint Test D.
B1261 1261 A/C solar radiation sensor circuit short
to ground
GO to Pinpoint Test D.
B1242 1242 Recirc door short/failure GO to Pinpoint Test E.
B1263 1263 Panel/defrost door short/failure GO to Pinpoint Test F.
B1264 1264 Floor door short/failure GO to Pinpoint Test F.
B2268 2268 Steering wheel auxiliary control switch
open circuit
If vehicle is not equipped with steering wheel control switches, ignore this code and continue diagnosis. If vehicle is
equipped with steering wheel control switches, GO to Pinpoint Test G.
B2269 2269 Steering wheel auxiliary control switch
circuit short to ground
GO to Pinpoint Test G.
U1040 1040 SCP invalid or missing data for
function read vehicle speed
If DTCs are present in the instrument cluster, diagnose those codes first. CLEAR the DTCs. If the EATC DTC returns,
INSTALL a new EATC module. REFER to Section 412-01.
If no DTCs are present in the instrument cluster, CLEAR the DTCs. If the EATC DTC returns, INSTALL a new EATC
module. REFER to Section 412-01. TEST the system for normal operation.
U1073 N/A SCP invalid or missing data for engine
coolant
If DTCs are present in the instrument cluster, diagnose those codes first. CLEAR the DTCs. If the EATC DTC returns,
INSTALL a new EATC module. REFER to Section 412-01. TEST the system for normal operation.
If no DTCs are present in the instrument cluster, CLEAR the DTCs. If the EATC DTC returns, INSTALL a new EATC
module. REFER to Section 412-01. TEST the system for normal operation.
U1112 1112 SCP invalid or missing data for interior
lamps
GO to Section 417-02, Inspection and Verification to continue diagnosis.
B1342 1342 Module faulted Button held too long may set DTC. Attempt to clean buttons. If code returns, INSTALL a new EATC module. REFER to
Section 412-01.
B1200 1200 Stuck button INSTALL a new EATC module. REFER to Section 412-01.
B2477 2477 Module not configured — LHD only CONFIGURE the EATC module. REFER to Section 418-01.
B1676 1676 Voltage out of range GO to Pinpoint Test H.
SYMPTOM CHART
Condition Possible Sources Action
 The steering wheel control
switch is inoperative/does not
operate correctly
 Circuitry short/open
 Steering wheel control
switch
 EATC module
 GO to Pinpoint Test G.
 No communication with the
electronic automatic
temperature control (EATC)
module
 Fuse(s)
 Circuitry short/open
 EATC module
communication
network
 GO to Pinpoint Test H.
 The EATC system is
inoperative, intermittent or
incorrect operation
 Fuse(s)
 Circuitry short/open
 Input sensor(s)/erratic
input signals
 Automatic temperature
control sensor hose
and elbow
 GO to Pinpoint Test I.
 Insufficient air conditioning (A/C)
cooling
 Restricted A/C
evaporator core orifice
 GO to Refrigerant System Tests in this section.
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Pinpoint Tests
Pinpoint Test A: DTC B2266 Or DTC B2267 — Blend Door Failure Or Short
Refer to Wiring Diagrams Cell 55, Automatic Climate Control System for schematic and connector information.
Normal Operation
Under normal operation, the driver side (LH) and passenger side (RH) temperature blend door actuator motors are supplied voltage or ground on circuit 245 (BN/LG) (LH) or circuit 1125
(BN) (RH), depending on desired actuator rotation, by the electronic automatic temperature control (EATC) module. The EATC module then supplies the appropriate voltage or ground to
the other side of the actuator motor on circuit 246 (VT) (LH) or circuit 1124 (WH) (RH).
The driver side (LH) and passenger side (RH) temperature blend door actuator feedback resistors are supplied a ground from the EATC module by circuit 438 (RD/WH) and a 5 volt
reference voltage on circuit 436 (RD/LG). The EATC module reads the voltage on circuit 437 (RD/WH) (LH) or circuit 1122 (RD) (RH) to determine the actuator position by the position of
the actuator feedback resistor wiper arm.
Possible Causes
 An open, short to voltage, ground or together in circuits 245 (BN/LG), 246 (VT), 436 (RD/LG), 437 (RD/WH), 438 (RD/WH), 1124 (WH) or 1125 (BN)
 Driver side (LH) or passenger side (RH) temperature blend door actuator
 Electronic automatic temperature control (EATC) module
 Stuck or bound linkage or door
 Low refrigerant level
 A/C cycling switch
 Temperature blend
door actuator control
 Insufficient, erratic or no heat  Low engine coolant
level
 Engine overheating
 Plugged or partially
plugged heater core
 Temperature blend
door binding or stuck
 A/C electric blend door
actuator
 Blend door circuit
open/shorted
 GO to Pinpoint Test J.
 The air conditioning (A/C) is
inoperative
 Fuse(s)
 A/C clutch relay
 Circuitry short or open
 A/C cycling switch

A/C system discharged
or low charge
 A/C compressor clutch
 A/C pressure
transducer
 EATC module
 PCM
 GO to Pinpoint Test K.
 The air conditioning (A/C) is
always on
 Circuitry short or open
 EATC module
 A/C clutch relay
 A/C compressor clutch
 A/C evaporator core
temperature sensor
 GO to Pinpoint Test L.
 The blower motor is inoperative  Fuse(s)
 Circuitry open or
shorted
 Blower motor
 Blower motor speed
control
 Blower motor relay
 GO to Pinpoint Test M.
 The blower motor does not
operate correctly
 Blower motor speed
control
 EATC module
 Circuit short or open
 GO to Pinpoint Test N.
 The rear audio and climate
control switch is
inoperative/does not operate
correctly.
 Fuse
 Circuitry short or open
 Rear audio/climate
control switch
 Rear audio/climate
control module
 Audio control module
(ACM)
 EATC module
 GO to Pinpoint Test O.
 The temperature set point does
not repeat after turning the
ignition switch off
 Fuse
 Circuitry short or open
 EATC module
 VERIFY central junction box (CJB) fuse 27 (10A) is OK. If OK, CHECK circuit 1566
(RD/YE) for an open and REPAIR as necessary. If OK, INSTALL a new EATC module.
 The electronic automatic
temperature control is
inoperative/does not operate
correctly — EATC
 Temperature blend
door/actuator
broken/binding
 EATC module
 CHECK the temperature blend doors/actuators for a binding or broken condition. If no
condition is found, INSTALL a new EATC module.
 The temperature display will not
switch between Celsius and
Fahrenheit
 EATC module  INSTALL a new EATC/EATC module.
 Inaccurate external temperature
display
 EATC module  REFER to description and operation of the EATC External Temperature Display. If the
external temperature display is not operating as described and no DTC is present,
CARRY OUT the ambient temperature sensor component test in this section. If the
sensor tests OK, INSTALL a new EATC module. REFER to Section 412-01. TEST the
system for normal operation.
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PINPOINT TEST A: DTC B2266 OR B2267
Test Step Result / Action to Take
A1 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE
 Disconnect: HVAC Module C228a.
 Disconnect: HVAC Module C228b.
 Measure the resistance between HVAC module C228b-8, circuit 436 (RD/LG), harness side and
HVAC module C228a-20, circuit 438 (RD/WH), harness side.
 Is the resistance greater than 500 ohms?
Yes
For DTC B2266,GO to A2.
For DTC B2267,GO to A3.
No
CARRY OUT the Blend Door Actuator Component Test in this section. If
the actuator tests OK, REPAIR circuits 436 (RD/LG) and 438 (RD/WH)
for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the
system for normal operation.
A2 CHECK POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
 Measure the low-side resistance between HVAC module C228b-4, circuit 437 (YE/LG), harness
side and HVAC module C228a-20, circuit 438 (RD/WH), harness side.
 Measure the high-side resistance between HVAC module C228b-4, circuit 437 (YE/LG), harness
side and HVAC module C228b-8, circuit 436 (RD/LG), harness side.
 Is the resistance between 250 and 5,500 ohms?
Yes
GO to A4.
No
CARRY OUT the Blend Door Actuator Component Test in this section. If
the actuator tests OK and:
If the low-side resistance only is greater than 5,500 ohms, REPAIR
circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the low-side resistance only is less than 250 ohms, REPAIR circuits
437 (YE/LG) and 438 (RD/WH) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the high-side resistance only is greater than 5,500 ohms, REPAIR
circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the high-side resistance only is less than 250 ohms, REPAIR circuits
437 (YE/LG) and 436 (RD/LG) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the high-side and low-side resistance is greater than 5,500 ohms,
REPAIR circuit 437 (YE/LG) for an open. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
A3 CHECK POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
 Measure the low-side resistance between HVAC module C228b-5, circuit 1122 (RD), harness
side and HVAC module C228a-20, circuit 438 (RD/WH), harness side.
 Measure the high-side resistance between HVAC module C228b-5, circuit 1122 (RD), harness
side and HVAC module C228b-8, circuit 436 (RD/LG), harness side.
Yes
GO to A4.
No
CARRY OUT the Blend Door Actuator Component Test in this section. If
the actuator tests OK and:
If the low-side resistance only is greater than 5,500 ohms, REPAIR
circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the low-side resistance only is less than 250 ohms, REPAIR circuits
1122 (RD) and 438 (RD/WH) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the high-side resistance only is greater than 5,500 ohms, REPAIR
circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the high-side resistance only is less than 250 ohms, REPAIR circuits
1122 (RD) and 436 (RD/LG) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the high-side and low-side resistance is greater than 5,500 ohms,
REPAIR circuit 1122 (RD) for an open. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
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 Is the resistance between 250 and 5,500 ohms?
A4 CHECK CIRCUITS 436 (RD/LG), 437 (YE/LG) AND 1122 (RD) FOR A SHORT TO GROUND
 Measure the resistance between ground and the following:
 HVAC module C228b-8, circuit 436 (RD/LG), harness side.
 For DTC B2266, HVAC module C228b-4, circuit 437 (YE/LG), harness side.
 For DTC B2267, HVAC module C228b-5, circuit 1122 (RD), harness side.
 Is the resistance greater than 10,000 ohms?
Yes
GO to A5.
No
REPAIR circuit(s) for a short to ground. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
A5 CHECK CIRCUITS 436 (RD/LG), 438 (RD/WH), 437 (YE/LG) AND 1122 (RD) FOR A SHORT TO
VOLTAGE
 Measure the voltage between ground and the following:
 HVAC module C228a-20, circuit 438 (RD/WH), harness side.
 HVAC module C228b-8, circuit 436 (RD/LG), harness side.
 For DTC B2266, HVAC module C228b-4, circuit 437 (YE/LG), harness side.
 For DTC B2267, HVAC module C228b-5, circuit 1122 (RD), harness side.
 Is any voltage present?
Yes
REPAIR circuit(s) for a short to voltage. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
No
For DTC B2266,GO to A6.
For DTC B2267,GO to A7.
A6 CHECK THE BLEND DOOR ACTUATOR OPERATION
NOTE: If a jumper fuse opens while carrying out this test step, repair the circuit(s) for a short.
 Ignition ON.
 Measure the resistance between HVAC module C228b-4, circuit 437 (YE/LG), harness side and
HVAC module C228a-20, circuit 438 (RD/WH), harness side.
 While observing the resistance, connect a fused jumper wire between:
 HVAC module C228a-26, circuit 245 (BN/LG), harness side and HVAC module C228b-11,
circuit 1566 (RD/YE), harness side.
 HVAC module C228a-13, circuit 246 (VT), harness side and HVAC module C228a-2, circuit
57 (BK), harness side.
Yes
INSPECT for broken door and linkage. REPAIR as necessary. If no
condition is found, GO to A9.
No
GO to A8.
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 Remove the fused jumpers when the resistance does not change.
 Connect a fused jumper wire between:
 HVAC module C228a-13, circuit 246 (VT), harness side and HVAC module C228b-11,
circuit 1566 (RD/YE), harness side.
 HVAC module C228a-26, circuit 245 (BN/LG), harness side and HVAC module C228a-2,
circuit 57 (BK), harness side.
 Does the resistance smoothly increase and/or decrease when the jumpers are connected?
A7 CHECK THE BLEND DOOR ACTUATOR OPERATION
NOTE: If a jumper fuse opens while carrying out this test step, repair the circuit(s) for a short.
 Ignition ON.
 Measure the resistance between HVAC module C228b-5, circuit 1122 (RD), harness side and
HVAC module C228a-20, circuit 438 (RD/WH), harness side.
 While observing the resistance, connect a fused jumper wire between:
 HVAC module C228a-12, circuit 1125 (BN), harness side and HVAC module C228b-11,
circuit 1566 (RD/YE), harness side.
 HVAC module C228a-11, circuit 1124 (WH), harness side and HVAC module C228a-2,
circuit 57 (BK), harness side.
 Remove the fused jumpers when the resistance does not change.
 Connect a fused jumper wire between:
 HVAC module C228a-11, circuit 1124 (WH), harness side and HVAC module C228b-11,
circuit 1566 (RD/YE), harness side.
 HVAC module C228a-12, circuit 1125 (BN), harness side and HVAC module C228a-2,
circuit 57 (BK), harness side.
Yes
INSPECT for broken door and linkage. REPAIR as necessary. If no
condition is found, GO to A9.
No
GO to A8.
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 Does the resistance smoothly increase and/or decrease when the jumpers are connected?
A8 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR AN OPEN
NOTE:
Due to limited connector accessibility, before carrying out this test step, visually inspect the
wiring between the HVAC module and actuator for opens or shorts. If no damage is visually
evident, proceed with the test.
 Ignition OFF.
 Disconnect: For DTC B2266, LH Temperature Blend Door Actuator C2091.
 Disconnect: For DTC B2267, RH Temperature Passenger Blend Door Actuator C2092.
DTC B2266
 NOTE: For DTC B2266 only.
 Measure the resistance between HVAC module C228a-26, circuit 245 (BN/LG), harness side and
the LH temperature blend door actuator C2091-6, circuit 245 (BN/LG), harness side.
DTC B2266
 NOTE: For DTC B2266 only.
 Measure the resistance between HVAC module C228a-13, circuit 246 (VT), harness side and the
LH temperature blend door actuator C2091-1, circuit 246 (VT), harness side.
DTC B2267
 NOTE: For DTC B2267 only.
 Measure the resistance between HVAC module C228a-12, circuit 1125 (BN), harness side and
the RH temperature blend door actuator C2092-6, circuit 1125 (BN), harness side.
DTC B2267
Yes
INSPECT for binding or broken linkage. REPAIR as necessary. If no
condition is found, INSTALL a new door actuator. TEST the system for
normal operation.
No
REPAIR the circuit(s) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
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Pinpoint Test B: DTC B1251 Or DTC B1253 — A/C In-Vehicle Temperature Sensor Open Circuit Or Short To Ground
Refer to Wiring Diagrams Cell 55, Automatic Climate Control System for schematic and connector information.
Normal Operation
Under normal operation, the in-vehicle air temperature sensor receives a ground from the electronic automatic temperature control (EATC) module through circuit 3059 (YE/LG). A 5-volt
reference voltage is supplied to the in-vehicle air temperature sensor from the EATC module through circuit 3058 (LG/RD).
Possible Causes
 An open in circuit 3059 (YE/LG) or 3058 (LG/RD)
 A short together in circuit 3059 (YE/LG) and 3058 (LG/RD)
 A short to ground in circuit 3058 (LG/RD)
 In-vehicle air temperature sensor
 Electronic automatic temperature control (EATC) module
PINPOINT TEST B: DTC B1251 OR DTC B1253 — A/C IN-VEHICLE TEMPERATURE SENSOR OPEN CIRCUIT OR SHORT TO GROUND
 NOTE: For DTC B2267 only.
 Measure the resistance between HVAC module C228a-11, circuit 1124 (WH), harness side and
the RH temperature blend door actuator C2092-1, circuit 1124 (WH), harness side.
 Is the resistance less than 5 ohms?
A9 CHECK HVAC MODULE CONNECTION
 Carry out the HVAC Module Cold Boot Process.
 Carry out the HVAC Module On-Demand Self Test.
 Operate the system.
 Does the concern return?
Yes
INSTALL a new HVAC module. REFER to Section 412-01. TEST the
system for normal operation.
No
The system is operating correctly at this time. The concern may have
been caused by a loose or corroded connector. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
Test Step Result / Action to Take
B1 CHECK THE SENSOR RESISTANCE
 Ignition OFF.
 Disconnect: In-Vehicle Temperature Sensor C233.
 Measure the resistance between the in-vehicle temperature sensor pins, component
side.
 Note the ambient temperature and compare the in-
vehicle temperature sensor resistance
with the table below.
 Is the resistance within the specified values for the temperature range?
Temperature Resistance
10-20°C (50-68°F) 37,000-58,000 ohms
20-30°C (68-86°F) 24,000-37,000 ohms
30-40°C (86-104°F) 16,000-24,000 ohms
Yes
GO to B2.
No
INSTALL a new in-vehicle temperature sensor. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
B2 CHECK THE EATC MODULE OUTPUT VOLTAGE
 Ignition ON.
 Press the AUTO button on the EATC module.
 Measure the voltage between in-vehicle temperature sensor C233-1, circuit 3058
(LG/RD) and C233-2, circuit 3059 (YE/LG).
Yes
INSTALL a new in-vehicle temperature sensor. TEST the system for normal
operation. If the code returns, INSTALL a new EATC module. TEST the system
for normal operation.
No
If diagnosing DTC B1251, GO to B3 . If diagnosing DTC B1253, GO to B5 .
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 Is the voltage between 4.7 and 5.1 volts?
B3 CHECK CIRCUIT 3058 (LG/RD) FOR AN OPEN
 Ignition OFF.
 Disconnect: EATC Module C228b.
 Measure the resistance between EATC module C228b-19, circuit 3058 (LG/RD) and in-
vehicle temperature sensor C233-1, circuit 3058 (LG/RD).
 Is the resistance less than 5 ohms?
Yes
GO to B4.
No
REPAIR circuit 3058 (LG/RD) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
B4 CHECK CIRCUIT 3059 (YE/LG) FOR AN OPEN
 Measure the resistance between EATC module C228b-16, circuit 3059 (YE/LG) and in-
vehicle temperature sensor C233-2, circuit 3059 (YE/LG).
 Is the resistance less than 5 ohms?
Yes
GO to B7.
No
REPAIR circuit 3059 (YE/LG) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
B5 CHECK CIRCUIT 3058 (LG/RD) FOR A SHORT TO CIRCUIT 3059 (YE/LG)
 Ignition OFF.
 Disconnect: EATC Module C228b.
 Measure the resistance between in-vehicle temperature sensor C233-1, circuit 3058
(LG/RD) and C233-2, circuit 3059 (YE/LG).
 Is the resistance greater than 10,000 ohms?
Yes
GO to B6.
No
REPAIR circuit 3058 (LG/RD) for a short to circuit 3059 (YE/LG). CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
B6 CHECK CIRCUIT 3058 (LG/RD) FOR A SHORT TO GROUND
 Measure the resistance between EATC module C228b-19, circuit 3058 (LG/RD) and
ground.
 Is the resistance greater than 10,000 ohms?
Yes
GO to B7.
No
REPAIR circuit 3058 (LG/RD) for a short to ground. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
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Pinpoint Test C: DTC B1255 Or DTC B1257 — A/C Ambient Temperature Sensor Open Circuit Or Short To Ground
Refer to Wiring Diagrams Cell 55, Automatic Climate Control System for schematic and connector information.
Normal Operation
Under normal operation, the A/C ambient temperature sensor receives a ground from the electronic automatic temperature control (EATC) module through circuit 3059 (YE/LG). A 5-volt
reference voltage is supplied to the A/C ambient temperature sensor from the EATC module through circuit 3061 (LB/OG).
Possible Causes
 An open in circuit 3059 (YE/LG) or 3061 (LB/OG)
 A short together in circuit 3059 (YE/LG) and 3061 (LB/OG)
 A short to ground in circuit 3061 (LB/OG)
 A/C ambient temperature sensor
 Electronic automatic temperature control (EATC) module
PINPOINT TEST C: DTC B1255 OR DTC B1257 — A/C AMBIENT TEMPERATURE SENSOR OPEN CIRCUIT OR SHORT TO GROUND
B7 CHECK MODULE CONNECTION
 Carry out the Electronic Automatic Temperature Control (EATC) Module Cold Boot
Process.
 Carry out the EATC on-demand self test.
 Operate the system.
 Does the concern return?
Yes
INSTALL a new EATC module. REFER to Section 412-01. TEST the system for
normal operation.
No
The system is operating correctly at this time. The concern may have been
caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
Test Step Result / Action to Take
C1 CHECK THE AMBIENT TEMPERATURE SENSOR RESISTANCE
 Ignition OFF.
 Disconnect: Ambient Temperature Sensor C132.
 Measure the resistance between the ambient temperature sensor terminals.
 Is the resistance within the specified values for these temperature ranges: 10-20°C (50-68°F),
37,000-58,000 ohms; 20-30°C (68-86°F), 24,000-37,000 ohms; 30-40°C (86-104°F), 16,000-24,000
ohms?
Yes
GO to C2.
No
INSTALL a new ambient air temperature sensor and bracket.
CLEAR the DTCs. REPEAT the self-test. TEST the system for
normal operation.
C2 CHECK THE EATC MODULE OUTPUT VOLTAGE
 Ignition ON.
 Press the AUTOMATIC button.
 Measure the voltage between ambient temperature sensor C132-1, circuit 3061 (LB/OG) and C132-2,
circuit 3059 (YE/LG).
 Is the voltage between 4.7 and 5.1 volts?
Yes
INSTALL a new ambient air temperature sensor. TEST the system
for normal operation. If the code returns, GO to C7 .
No
If diagnosing DTC 1255, GO to C3 . If diagnosing DTC 1257, GO to
C5 .
C3 CHECK CIRCUIT 3061 (LB/OG) FOR AN OPEN
 Ignition OFF.
 Disconnect: EATC Module C228a.
 Measure the resistance between EATC module C228b-17, circuit 3061 (LB/OG) and ambient
temperature sensor C132-1, circuit 3061 (LB/OG).
Yes
GO to C4.
No
REPAIR circuit 3061 (LB/OG) for an open. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
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Pinpoint Test D: DTC B1259 Or DTC B1261 — Solar Radiation Sensor Open Circuit Or Short To Ground
Refer to Wiring Diagrams Cell 55, Automatic Climate Control System for schematic and connector information.
Normal Operation
Under normal operation, the solar radiation sensor receives a ground through circuit 676 (PK/OG). A 5-volt reference voltage is supplied to the solar radiation sensor from the EATC module
through circuit 476 (BN/YE) (LH) and circuit 468 (BN) (RH).
Possible Causes
 Is the resistance less than 5 ohms?
C4 CHECK CIRCUIT 3059 (YE/LG) FOR AN OPEN
 Measure the resistance between EATC module C228b-16, circuit 3059 (YE/LG) and ambient
temperature sensor C132-2, circuit 3059 (YE/LG).
 Is the resistance less than 5 ohms?
Yes
GO to C7.
No
REPAIR circuit 3059 (YE/LG) for an open. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
C5 CHECK CIRCUIT 3061 (LB/OG) FOR A SHORT TO CIRCUIT 3059 (YE/LG)
 Ignition OFF.
 Disconnect: EATC Module C228a.
 Disconnect: EATC Module C228b.
 Measure the resistance between ambient temperature sensor C132-1, circuit 3061 (LB/OG) and
C132-2, circuit 3059 (YE/LG).
 Is the resistance greater than 10,000 ohms?
Yes
GO to C6.
No
REPAIR circuit 3061 (LB/OG) for a short to circuit 3059 (YE/LG).
CLEAR the DTCs. REPEAT the self-test. TEST the system for
normal operation.
C6 CHECK CIRCUIT 3061 (LB/OG) FOR A SHORT TO GROUND
 Measure the resistance between EATC module C228-17, circuit 3061 (LB/OG) and ground.
 Is the resistance greater than 10,000 ohms?
Yes
GO to C7.
No
REPAIR circuit 3061 (LB/OG) for a short to ground. CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
C7 CHECK MODULE CONNECTION
 Carry out the Electronic Automatic Temperature Control (EATC) Module Cold Boot Process.
 Carry out the EATC on-demand self test.
 Operate the system.
 Does the concern return?
Yes
INSTALL a new EATC module. REFER to Section 412-01. TEST the
system for normal operation.
No
The system is operating correctly at this time. The concern may
have been caused by a loose or corroded connector. CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
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 An open in circuit 476 (BN/YE), 468 (BN) or 676 (PK/OG)
 A short to ground in circuit 468 (BN) or 476 (BN/YE)
 Solar radiation sensor
 Electronic automatic temperature control (EATC) module
PINPOINT TEST D: DTC B1259 OR DTC B1261 — SOLAR RADIATION SENSOR OPEN CIRCUIT OR SHORT TO GROUND
Test Step Result / Action to Take
D1 CHECK THE SOLAR RADIATION SENSOR RESISTANCE
 Ignition OFF.
 Disconnect: Solar Radiation Sensor C287.
 Measure the resistance between the solar radiation sensor terminals 2 and 6 and
between 1 and 2.
 Is continuity present and the resistance greater than 0 ohms?
Yes
GO to D2.
No
INSTALL a new solar radiation sensor and bracket. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
D2 CHECK THE EATC MODULE OUTPUT VOLTAGE
 Ignition ON.
 Press the AUTOMATIC button.
 Measure the voltage between solar radiation sensor C287-1, circuit 468 (BN) and
C287-2, circuit 676 (PK/OG).
 Measure the voltage between solar radiation sensor C287-2, circuit 676 (PK/OG) and
C287-6, circuit 476 (BN/YE).
 Are the voltages between 4.7 and 5.1 volts?
Yes
GO to D7.
No
If diagnosing DTC 1259, GO to D3 . If diagnosing DTC 1261, GO to D5 .
D3 CHECK CIRCUIT 468 (BN) AND CIRCUIT 476 (BN/YE) FOR AN OPEN
 Ignition OFF.
 Disconnect: EATC Module C228b.
 Measure the resistance between EATC module C228b-6, circuit 468 (BN) and solar
radiation sensor C287-1, circuit 468 (BN).
 Measure the resistance between EATC module C228b-18, circuit 476 (BN/YE) and
solar radiation sensor C287-6, circuit 476 (BN/YE).
Yes
GO to D4.
No
REPAIR the circuit for an open. CLEAR the DTCs. REPEAT the self-test. TEST the
system for normal operation.
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 Is the resistance less than 5 ohms?
D4 CHECK CIRCUIT 676 (PK/OG) FOR AN OPEN
 Measure the resistance between solar radiation sensor C287-2, circuit 676 (PK/OG)
and ground.
 Is the resistance less than 5 ohms?
Yes
GO to D7.
No
REPAIR circuit 676 (PK/OG) for an open. CLEAR the DTCs. REPEAT the self-test.
TEST the system for normal operation.
D5 CHECK CIRCUIT 468 (BN) AND 476 (BN/YE) FOR A SHORT TO CIRCUIT 676
(PK/OG)
 Ignition OFF.
 Disconnect: EATC Module C228b.
 Measure the resistance between solar radiation sensor C287-1, circuit 468 (BN) and
C287-2, circuit 676 (PK/OG).
 Measure the resistance between solar radiation sensor C287-6, circuit 476 (BN/YE)
and C287-2, circuit 676 (PK/OG).
 Are the resistances greater than 10,000 ohms?
Yes
GO to D6.
No
REPAIR circuit 468 (BN) or 476 (BN/YE) for a short to circuit 676 (PK/OG). CLEAR
the DTCs. REPEAT the self-test. TEST the system for normal operation.
D6 CHECK CIRCUIT 468 (BN) AND CIRCUIT 476 (BN/YE) FOR A SHORT TO GROUND
 Measure the resistance between solar radiation sensor C287-1, circuit 468 (BN) and
ground.
 Measure the resistance between solar radiation sensor C287-6, circuit 476 (BN/YE)
and ground.
Yes
GO to D7.
No
REPAIR circuit 468 (BN) or 476 (BN/YE) for a short to ground. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
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Pinpoint Test E: DTC B1242 — Recirculation Door Failure
Refer to Wiring Diagrams Cell 55, Automatic Climate Control System for schematic and connector information.
Normal Operation
Under normal operation, the air inlet door actuator motor is supplied voltage or ground on circuit 1069 (OG/LB), depending on desired actuator rotation, by the EATC module. The EATC
module then supplies the appropriate voltage or ground to the other side of the actuator motor on circuit 660 (YE/LG).
The air inlet door actuator feedback resistor is supplied a ground from the EATC module through circuit 438 (RD/WH) and a 5-volt reference voltage on circuit 436 (RD/LG). The EATC
module reads the voltage on the air inlet door actuator feedback circuit 435 (YE/LB) to determine the air inlet door actuator position by the position of the actuator feedback resistor wiper
arm.
Possible Causes
 An open, short to voltage, ground or together in circuits 660 (YE/LG), 1069 (OG/LB), 438 (RD/WH), 436 (RD/LG) and 435 (YE/LB)
 Air inlet door actuator motor
 Electronic automatic temperature control (EATC) module
 Stuck or bound linkage or door
PINPOINT TEST E: DTC B1242 — RECIRCULATION DOOR FAILURE
 Are the resistances greater than 10,000 ohms?
D7 CHECK MODULE CONNECTION
 Carry out the Electronic Automatic Temperature Control (EATC) Module Cold Boot
Process.
 Carry out the EATC on-demand self test.
 Operate the system.
 Does the concern return?
Yes
INSTALL a new EATC module. REFER to Section 412-01. TEST the system for
normal operation.
No
The system is operating correctly at this time. The concern may have been caused
by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST
the system for normal operation.
Test Step Result / Action to Take
E1 CHECK THE RECIRC DOOR ACTUATOR CLOCKWISE OPERATION
 Disconnect: EATC Module C228a.
 Disconnect: EATC Module C228b.
 Remove the door actuator and disengage the actuator driveshaft from the actuator
door. Refer to Section 412-01.
 Mark the door actuator driveshaft position.
 Connect a fused jumper wire between:
 EATC module C228a-19, circuit 1069 (OG/LB) and EATC module C228b-
11, circuit 729 (RD/WH).
 EATC module C228a-10, circuit 660 (YE/LG) and EATC module C228a-2,
circuit 676 (PK/OG).
 Does the actuator motor move in the clockwise direction?
Yes
GO to E2.
No
GO to E3.
E2 CHECK THE RECIRC DOOR ACTUATOR COUNTERCLOCKWISE OPERATION
 Connect a fused jumper wire between:
 EATC module C228a-10, circuit 660 (YE/LG) and EATC module C228b-11,
circuit 729 (RD/WH).
 EATC module C228a-9, circuit 1069 (OG/LB) and EATC module C228a-2,
circuit 676 (PK/OG).
Yes
GO to E9.
No
GO to E3.
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 Does the actuator motor move in the counterclockwise direction?
E3 CHECK CIRCUIT 660 (YE/LG) FOR A SHORT TO GROUND
 Disconnect: Recirc Door Actuator C289.
 Measure the resistance between ground and EATC module C228a-10, circuit 660
(YE/LG).
 Is the resistance greater than 10,000 ohms?
Yes
GO to E4.
No
REPAIR circuit 660 (YE/LG) for a short to ground. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
E4 CHECK CIRCUIT 1069 (OG/LB) FOR A SHORT TO GROUND
 Measure the resistance between ground and EATC module C228a-9, circuit 1069
(OG/LB).
 Is the resistance greater than 10,000 ohms?
Yes
GO to E5.
No
REPAIR circuit 1069 (OG/LB) for a short to ground. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
E5 CHECK CIRCUIT 660 (YE/LG) FOR A SHORT TO VOLTAGE
 Ignition ON.
 Measure the voltage between ground and EATC module C228a-10, circuit 660
(YE/LG).
 Is voltage present?
Yes
REPAIR circuit 660 (YE/LG) for a short to voltage. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
No
GO to E6.
E6 CHECK CIRCUIT 1069 (OG/LB) FOR A SHORT TO VOLTAGE
 Measure the voltage between ground and EATC module C228a-9, circuit 1069
(OG/LB).
 Is voltage present?
Yes
REPAIR circuit 1069 (OG/LB) for a short to voltage. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
No
GO to E7.
E7 CHECK CIRCUIT 660 (YE/LG) FOR AN OPEN
 Ignition OFF. Yes
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 Measure the resistance between EATC module C228a-10, circuit 660 (YE/LG) and
the recirc door actuator C289-1, circuit 660 (YE/LG).
 Is the resistance less than 5 ohms?
GO to E8.
No
REPAIR circuit 660 (YE/LG) for an open. CLEAR the DTCs. REPEAT the self-test.
TEST the system for normal operation.
E8 CHECK CIRCUIT 1069 (OG/LB) FOR AN OPEN
 Measure the resistance between EATC module C228a-9, circuit 1069 (OG/LB) and
the recirc door actuator C289-6, circuit 1069 (OG/LB).
 Is the resistance less than 5 ohms?
Yes
INSPECT for binding or broken linkage. If no condition is found, INSTALL a new door
actuator. REFER to Section 412-01. CLEAR the DTCs. REPEAT the self-test. TEST
the system for normal operation.
No
REPAIR circuit 1069 (OG/LB) for an open. CLEAR the DTCs. REPEAT the self-test.
TEST the system for normal operation.
E9 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE
 Connect: Recirc Door Actuator C289.
 Disconnect: Temperature Blend Door Actuator C2091.
 Disconnect: Temperature Blend Door Actuator C2092.
 Disconnect: Panel/Defrost Door Actuator C2248.
 Disconnect: Floor Door Actuator C234.
 Measure the resistance between EATC module C228b-8, circuit 436 (RD/LG) and
EATC module C228a-20, circuit 438 (RD/WH).
 Is the resistance between 5,000 and 6,000 ohms?
Yes
GO to E10.
No
If the resistance is greater than 6,000 ohms, GO to E12 . If the resistance is less than
5,000 ohms, GO to E19 .
E10 CHECK POTENTIOMETER LOW SIDE RESISTANCE
 Measure the resistance between EATC module C228a-20, circuit 438 (RD/WH)
and EATC module C228b-3, circuit 435 (YE/LB).
 Is the resistance between 250 and 5,500 ohms?
Yes
GO to E11.
No
If the resistance is greater than 5,500 ohms, GO to E14 . If the resistance is less than
250 ohms, GO to E20 .
E11 CHECK POTENTIOMETER HIGH SIDE RESISTANCE
 Measure the resistance between EATC module C228b-8, circuit 436 (RD/LG) and
EATC module C228b-3, circuit 435 (YE/LB).
Yes
GO to E15.
No
If the resistance is greater than 5,500 ohms, INSTALL a new door actuator. REFER to
Section 412-01. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal
operation. If the resistance is less than 250 ohms, GO to E21 .
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 Is the resistance between 250 and 5,500 ohms?
E12 CHECK 436 (RD/LG) CIRCUIT FOR AN OPEN
 Disconnect: Recirc Door Actuator C289.
 Measure the resistance between EATC module C228b-8, circuit 436 (RD/LG) and
recirc door actuator C289-5, circuit 436 (RD/LG).
 Is the resistance less than 5 ohms?
Yes
GO to E13.
No
REPAIR circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-test.
TEST the system for normal operation.
E13 CHECK THE ACTUATOR RETURN CIRCUIT 438 (RD/WH) FOR AN OPEN
 Disconnect: Recirc Door Actuator C289.
 Measure the resistance between EATC module C228a-20, circuit 438 (RD/WH)
and recirc door actuator C289-4, circuit 438 (RD/WH).
 Is the resistance less than 5 ohms?
Yes
INSTALL a new door actuator. REFER to Section 412-01. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
No
REPAIR circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-test.
TEST the system for normal operation.
E14 CHECK CIRCUIT 435 (YE/LB) FOR AN OPEN
 Disconnect: Recirc Door Actuator C289.
 Measure the resistance between EATC module C228b-3, circuit 435 (YE/LB) and
recirc door actuator C289-3, circuit 435 (YE/LB).
 Is the resistance less than 5 ohms?
Yes
INSTALL a new door actuator. REFER to Section 412-01. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
No
REPAIR circuit 435 (YE/LB) for an open. CLEAR the DTCs. REPEAT the self-test.
TEST the system for normal operation.
E15 CHECK CIRCUIT 436 (RD/LG) FOR A SHORT TO GROUND
 Measure the resistance between EATC module C228b-8, circuit 436 (RD/LG) and
ground.
 Is the resistance greater than 10,000 ohms?
Yes
GO to E16.
No
REPAIR circuit 436 (RD/LG) for a short to ground. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
E16 CHECK CIRCUIT 435 (YE/LB) FOR A SHORT TO GROUND
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 Measure the resistance between ground and EATC module C228b-3, circuit 435
(YE/LB).
 Is the resistance greater than 10,000 ohms?
Yes
GO to E17.
No
REPAIR circuit 435 (YE/LB) for a short to ground. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
E17 CHECK CIRCUIT 436 (RD/LG) FOR A SHORT TO VOLTAGE
 Ignition ON.
 Measure the voltage between EATC module C228b-8, circuit 436 (RD/LG) and
ground.
 Is voltage present?
Yes
REPAIR circuit 436 (RD/LG) for a short to voltage. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
No
GO to E18.
E18 CHECK CIRCUIT 435 (YE/LB) FOR A SHORT TO VOLTAGE
 Measure the voltage between ground and EATC module C228b-3, circuit 435
(YE/LB).
 Is voltage present?
Yes
REPAIR circuit 435 (YE/LB) for a short to voltage. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
No
INSPECT for binding or broken door and linkage. If no condition is found, GO to E22 .
E19 CHECK CIRCUIT 438 (RD/WH) AND CIRCUIT 436 (RD/LG) FOR A SHORT
TOGETHER
 Disconnect: Recirc Door Actuator C289.
 Measure the resistance between EATC module C228a-20, circuit 438 (RD/WH)
and EATC module C228b-8, circuit 436 (RD/LG).
 Is the resistance less than 5 ohms?
Yes
REPAIR circuits 438 (RD/WH) and circuit 436 (RD/LG) for a short together. CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
No
INSTALL a new door actuator. REFER to Section 412-01. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
E20 CHECK CIRCUIT 438 (RD/WH) AND CIRCUIT 435 (YE/LB) FOR A SHORT
TOGETHER
 Measure the resistance between EATC module C228a-20, circuit 438 (RD/WH)
and EATC module C228b-3, circuit 435 (YE/LB).
Yes
REPAIR circuits 438 (RD/WH) and circuit 435 (YE/LB) for a short together. CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
No
INSTALL a new door actuator. REFER to Section 412-01. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
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Pinpoint Test F: DTC B1263 or B1264 — Panel/Defrost or Floor Door Failure
Refer to Wiring Diagrams Cell 55, Automatic Climate Control System for schematic and connector information.
Normal Operation
The panel/defrost and floor door actuator motors both work the same. Each door actuator motor has 2 circuits that the HVAC module applies voltage to and reverses the polarity to reverse
door actuator motor rotation. The panel/defrost door actuator motor circuits are 1379 (PK/LB) and 1380 (TN/YE); the floor door actuator motor circuits are 1375 (PK/YE) and 1376 (BK/LB).
Each door actuator motor has a position sensor that supplies a voltage to the HVAC module to indicate door position. Both door actuator motors receive reference voltage (5V) on circuit
436 (RD/LG) and a sensor ground on circuit 438 (RD/WH). Position signals are provided by the panel/defrost door actuator motor on circuit 1123 (YE/WH) and circuit 1130 (PK/LG) by the
floor door actuator motor.
 DTC B1263 (Servo Motor Vent Circuit Failure) — The module senses no change in actuator feedback voltage when the actuator motor has been energized.
 DTC B1264 (Servo Motor Foot Circuit Failure) — The module senses no change in actuator feedback voltage when the actuator motor has been energized.
This pinpoint test is intended to diagnose the following:
 Wiring, terminals or connectors
 Panel/defrost or floor door actuator
 HVAC module
 Stuck or bound linkage or door
PINPOINT TEST F: DTC B1263 OR B1264 — PANEL/DEFROST OR FLOOR DOOR FAILURE
 Is the resistance less than 5 ohms?
E21 CHECK CIRCUIT 436 (RD/LG) AND CIRCUIT 435 (YE/LB) FOR A SHORT
TOGETHER
 Measure the resistance between EATC module C228b-8, circuit 436 (RD/LG) and
EATC module C228b-3, circuit 435 (YE/LB).
 Is the resistance less than 5 ohms?
Yes
REPAIR circuits 436 (RD/LG) and circuit 435 (YE/LB) for a short together. CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
No
INSTALL a new door actuator. REFER to Section 412-01. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
E22 CHECK MODULE CONNECTION
 Carry out the Electronic Automatic Temperature Control (EATC) Module Cold Boot
Process.
 Carry out the EATC on-demand self test.
 Operate the system.
 Does the concern return?
Yes
INSTALL a new EATC module. REFER to Section 412-01. TEST the system for normal
operation.
No
The system is operating correctly at this time. The concern may have been caused by a
loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the
system for normal operation.
Test Step Result / Action to Take
F1 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE
 Disconnect: HVAC Module C228a.
 Disconnect: HVAC Module C228b.
 Measure the resistance between HVAC module C228b-8, circuit 436 (RD/LG),
harness side and HVAC module C228a-20, circuit 438 (RD/WH), harness side.
 Is the resistance greater than 500 ohms?
Yes
If diagnosing DTC B1263, GO to F3.
If diagnosing DTC B1264, GO to F4.
No
GO to F2.
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