AMC Jeep ET-501 User manual

FI AMC! Jeep
CEC FUEL
FEEDBACK SYSTEM TESTER
ET-501
INSTRUCTION MANUAL

»
>
i
"1
FOREWORD
This Instruction Manual fully describes the operation of the C.E.C. Fuel Feedback System Tester (ET-501); j
explaining its function of analyzing the output generated by the sensors which are part of the Com- 1
puterized Emission Control (CEC) System on AMC and Jeep 6-cylinder and 4-cylinder engines manufac¬
tured from 1981 through 1984 with this system. ' • ' ' ;
•: . /'. -I
Partitioned into five section^, this Instruction Manual is conveniently organized with handy divider tabs ' , ■■ ]
to insure the quick and easy locating of information. • . ;*jj
; , -J
The General Information section highlights the Tester’s description, design features, and replaceable
parts, as well as explaining the operation of the CEC Fuel Feedback System’s open- and closed-loop }
modes. A listing of the definitions of the abbreviated response displays is also included to aid you. in
readily understanding them. * . - .
Flow charts for both the ©-cylinder and 4-cylinder engines have been divided into their respective sections
in addition to a unit being devoted to diagnostic schematic drawings. In this section you’ll find informa- i
tion on the new diagnostic connectors and microprocessing unit (MCU) pin connectors found, on our • \i
1983-1984 vehicles.
Throughout the various {low charts, we have made use of the following two symbols:
* j ‘ _ • • * . . _ i..' • . ;
. >= greater than . •
'* , ■ • ••.•* * .. « • *
• <= Less than. . '• ' • ■ '. •
. .. •'*' ' ‘ • •• • ' ’ _ '
For example, the instructions;-‘‘<1.5” should be understood to mean “folfow the-path marked ‘<1.5,’ if -
the reading after the test is less than .1.5.” For a reading g/eater than 1.5, you should follow the path
marked “>1.5.” v. ‘ • '' ■ • * '
' • ' ? . •
The fifth section, Bulletins; has-been set aside to assist you in keeping this Instruction Manual current.
Any information subsequently issued by AMC/Je'ep Or the Tester’s manufacturer should be placed in this
section, Be sure to either remove out-dated information or mark the-revisions and their effective dates on
any information which remains jn thiS'manuart. ..
'• . r -'vv . •/ .... ; . .
Use of the information contained in this Instruction Manual will enable you to professionally service the
CEC Fuel Feedback System with the ET-501 Tester. Any questions regarding information not covered
here should be submitted to yoUr 2fone'bffice or to.the Tester’s manufacturer. -
NOTE: The material contained in ihis -editjon of the CEC Fuel Feedback System Tester Instruction ,
Manual supersedes any and allpre.ViQuSly released Instruction Manuals.. * • ’

SAFETY PRECAUTIONS
This unit should be used only by a qualified technician knowledgeable in the handling of this type of
equipment.
Do not run engine in a confined area or garage when performing tests. Use adequate shop ex¬
haust ventilation system to prevent carbon monoxide poisoning.
Exposing tester or tester wires to hot or moving engine components may result in PERSONAL
INJURY and/or tester damage.
Do not run hook-up leads over the engine fan, pump, or belt areas. Route leads outside of
engine compartment.
• Securely set the emergency brake, parking brake, and block the wheels before performing tests
or maintenance on engine.
• Check to insure that the hood support rod is fully engaged or that the spring assisted hood lift
is capable of supporting the hood in the position it is placed in.
• Wear approved eye protection when working near the engine or battery.
• Keep lighted cigarettes, sparks, flames or other ignition sources away from battery and fuel
vapors at all times.
• Do not lay tools or equipment on battery. Accidentally grounding the “hot” battery terminal can
shock or burn you and damage wiring, battery and tools or tester.
• When connecting battery test leads, be careful to avoid sparks which could cause the battery
to explode.
• Avoid contact with hot surfaces such as exhaust manifolds and pipes, radiator and hoses, etc.
• Remove tools from vehicle before starting engine. Tools can shake off, fall into fan blades and
drive pulleys, and be propelled into the air, which could result in property damage and/or injury.
• Keep out of a direct line with fan blades when testing.
i

WARRANTY
t
THIS WARRANTY IS EXPRESSLY LIMITED TO PERSONS WHO PURCHASE OTC PRODUCTS FOR PUR¬
POSES OP RESALE OR USE IN THE ORDINARY COURSE OF THE BUYER’S BUSINESS.
This Owatonna Tool Company electronic product is warranted against defects in materials and workman¬
ship for 1 year (12 months) from date of delivery to the user. This warranty does not cover any part that has
been abused, altered, used for a purpose other than that for which it was intended, or used in a manner in¬
consistent with instructions regarding use. The exclusive remedy for any electronic tester found to be
defective is repair or replacement, and OTC shall not be liable for any consequential or incidental
damages. Final determination of defects shall be made by OTC in accordance with procedures estab¬
lished by OTC. No agent, employee or representative of OTC has any authority to bind OTC to any affirma¬
tion, representation or warranty concerning OTC electronic testers, except as stated herein.
DISCLAIMER
THE ABOVE WARRANTY IS IN LIEU OF ANY OTHER WARRANTY, EXPRESSED OR IMPLIED INCLUDING
ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
REPAIR SERVICE AVAILABLE
The manufacturer will repair and return to the purchaser any unit after expiration of the warranty for a
nominal service and freight charge. Return the unit prepaid to:
• • • Owatonna Tool Company
OwatonnS, MN 55060
Attni'Service Repair Dept.

TABLE OF CONTENTS
GENERAL INFORMATION
Description .....1
Design Features.1
Replaceable Parts.. '..2
CEC Fuel Feedback System Operation.3
Operating Instructions.,..3
Definition of Tester Displays.6
6-CYLINDER frJLl /
DOUIMTEST — Perform Electronic Ignition Retard Test.2
CKGND + PWR FEED Test for 81-82.3
CK GND + PWR FEED Test for 83-84.4
CK RPM SIGNAL Test for 81-82.5
CK RPM SIGNAL Test for 83-84:..7
CK IDLE CKT Test for 82....9
CK IDLE CKT Test for 83-84. 1 1
CK CSW CKT Test for 81....13
CKCSWCKT Test for 82. 1 5
CK CSW CKT Test for 83-84..16
CK AIR MGMTSYS Test for81-82.17
CK AIR MGMTSYS Test for 83-84.19
CK TES CKT Test for 81...’.23
CK TES CKT Test for 82...25
CK TES CKT Test for 83-84....27
CK ALT CKT Test for 81 -82*.....29
CK ALT CKT Test for 83-84. 30
CK VSA Test for 81.;....31
CK VSA Test for 82-83-84..7...*. 35
CK STP MOT Test for 81-82.:.,....37
CK STP MOT Test for 83-84......‘.39
CK PCV SYS Test for 83-84. ; . . . . . 41
CK OPSW + CHOKE Test for 82-83-84.:..42
CK WOT CKT Test for 81. . . . . . . . . . . .43
CK WOT CKT Test for 82....7......44
CK WOT CKT Test for 83-84.. ....7.. .•...7 ...45
DO CLD LOOP TEST Test for 81....*...46.
DO CLD LOOP TEST Test for 82...7.I7.47
DO CLD LOOP TEST Test for 83-84 7 .7 7.....'.....48
RP ... OVER LEAN Test for 81-82-83-84...! . . 49
RP ... OVER RICH Test for 81-82-83-84.......:.50
4-CYLINDER / • ;
RP VSA Test for 83-84. ...... 7 _v..'..... 7 .... .2
CKGND + PWR FEED T.est for 83-84..:.... 7.2
CK RPM SIGNAL Test for 83-84...... .... .V .2
CK AIR MGMT SYS Test for 83-84. 7 ‘ ....2
CK CSW CKT Test for 83-84.7 .:.. . . ....2
CK ALT CKT Test for 83-84.... ..2
CK TES CKT Test for 83-84.: 7;.! _ _ __ _ _ :......2
CK VSA Test for 82-83-64 .. 7 . . . . . . . . 2
DO CLD LOOP TEST Test for 83^84.7 7.....2
)

TABLE OF CONTENTS (Cont’d)
4-CYLINDER (CONT’D)
CK INPUT CKTS Test for 83-84.;.2
CKCTS + CHOKE Test for 83-84.......3
CK KNOCK CKT Test for 83-84.4
CK WOT CKT Test for 83-84. : .. . *..5
NO DC SOL Test for 83-84.6
CK CHOKE + FEED Test for 83-84.. 7
CK CTS/WOT CKT Test for 83-84...9
CK IDLE CKT Test for 83-84.11
RP PCV SOL Test for 83-84.I.13
RP ... OVER LEAN Test for 83-84. '..15
RP ... OVER RICH Test for 83-84.;.16
CK AC CUT-OUT Test for 85 w/AC and Automatic Transmission . . . 1 7
SCHEMATICS
1981 6-Cylinder Vehicle Schematic...
1981 Diagnostic Connectors.'..
1982 6-Cylinder Vehicle Schematic.....
1982 6-Cylinder CEC System Schematic.
1982 6-Cylinder Diagnostic Connectors.
1983-84 6-Cylinder Vehicle Schematic.
1983-84 6-Cylinder Diagnostic Connectors.
1983-84 6-Cylinder Harness Connectors at MCU..
1983-84 AMC 4-Cylinder CEC System.
1983-84 AMC 4-Cylinder Engine Diagnostic Connectors.
1984 Jeep 4-Cylinder Pin and Socket Connector.
1984 Jeep Microprocessor Control Unit (MCU) Pin Connectors
Diagnostic Connectors.
1985 Jeep 4-Cylinder Pin and Socket Connectors.
1985 Jeep Microprocessor Control Unit (MCU) Pin Connectors
..2
..2
..3
..3
;.3
5
.8
.9
.9
10
11
Date: 9/84

/
*
General
Information

GENERAL
INFORMATION

General Information
DESCRIPTION
The AMC/Jeep Fuel Feedback System Tester is a microprocessor based service tool that will rapidly scan
the various circuits utilized by the Computerized Emission Control (CEC) System on AMC/Jeep 6-cylinder
and 4-cylinder engines. The tester will direct the service technician through a series of steps that will
allow the tester to verify if circuit voltages generated by components that make up the CEC system are
operating within tolerance. In minutes, the tester will have systematically checked the equivalent of ap¬
proximately 40 pages of service manual procedures and flow charts that would normally be checked
manually by a service technician.
These complete systematic checks are directed by software memory modules installed by the operator
into the tester. The memory modules have a memory capacity that will store up to 32,000 bits of informa¬
tion; enough to handle the AMC and Jeep 6-cylinder engines for 1981-1984 and enough to handle the AMC
and Jeep 4-cylinder engines for 1983 and 1984. The memory module is designed to be removable. The
6-cylinder module must be installed when testing a 6-cylinder system. The 4-cylinder module is used with
the 4-cylinder system. Be sure to check the module being used periodically to see that it is firmly seated;
especially if the tester unit has been dropped or mishandled.
DESIGN FEATURES
A 16 CHARACTER DISPLAY WINDOW will display data and direct the service technician to the necessary
steps needed to test the CEC system.
TOUCH/RESPONSE PADS located on the face of the tester will enter a response when touched by the ser¬
vice technician.
5 CONNECTOR CABLES are provided with the CEC tester. Two cables are designed to interface with
vehicle diagnostic connectors. The remaining cables will interface with a designated vehicle model year
micro computer control unit (MCU).
General Information 1

General Information
REPLACEABLE PARTS
ITEM PART NUMBER
Operator’s Instruction Manual (Not Shown).8981 320 761
Software Module Unit Assembly (6-cyl.).;.8981 320 762
Software Module Unit Assembly (4-cyl.).8981 320 763
Test Harness 1 (For 1981 6-cyl.).8981 320 764
Test Harness 2 (For 1981 6-cyl.).8981 320 765
Test Harness 3 (For 1982-1984 6-cyl. and 1983-1984 4-cyl.).8981 320 766
Test Harness 4 (For 1982 6-cyl.).8981 320 767
Test Harness 5 (For 1983-1984 6 & 4-cyl.).8981 320 768
Storage Box.8981 320 769
Insert..8981 320 770
Adapter. 8981 320 771
2 General Information

CEC FUEL FEEDBACK SYSTEM OPERATION
There are two primary modes of operation for the CEC Fuel Feedback System:
• open loop
• closed loop
OPEN LOOP
In the open loop mode, the system delivers only pre-determined air/fuel mixtures and ignores the make-up
of exhaust gases. The MCU does not have the ability to vary the air/fuel ratio except as pre-programmed
for certain engine operating conditions.
The CEC System will be in the open loop mode of operation whenever engine operating conditions do not
conform with the programmed criteria for closed loop operation. The air/fuel mixture is maintained at a
programmed ratio that is dependent on the type of engine operation involved. The oxygen sensor data is
not accepted by the CEC System during this mode of operation. The following conditions involve open
loop operation.
• Engine Start-Up
• Coolant or Air Temperature Too Low
• Oxygen Sensor Temperature Too Low
• Idle or Engine Deceleration
• Wide Open Throttle (WOT)
• Battery Voltage Too Low
CLOSED LOOP
In the closed loop mode, the system varies the air/fuel ratio in response to the amount of oxygen in the ex¬
haust gas. The MCU receives input signals from the Fuel Feedback System components and can adjust
the air/fuel ratio by signaling the various system outputs.
When all input data conforms with the programmed criteria for closed loop operation, the oxygen content
output voltage from the oxygen sensor is accepted by the microprocessor. This results in an air/fuel mix¬
ture that will be optimum for current engine operating conditions.
NOTE: The AMC CEC Fuel Feedback System Tester is designed to analyze the output generated by the
sensors that are part of the emission control system in both the open loop and the closed loop mode of
operation.
OPERATING INSTRUCTIONS
1. Connect the red positive ( + ) power lead cable of the tester unit to the positive side of the battery.
Connect the black negative (-) lead cable to the ground side of the battery.
CAUTION: The positive and negative lead cables of the tester unit must be connected first; before
another connection is made. Failure to do this could result in damage to the tester unit.
2. Upon completion of the battery connections, the 6-cylinder module will display a request for model
year of the test vehicle. The 4-cylinder module will display an inquiry; is the test vehicle a U.S. or
Canadian version? The service technician must press the correct touch pad to indicate a response
to the displays.
General Information 3

General Informatioi
Operating Instructions (Continued)
PRESS TO
ANSWER 83
PRESS TO
ANSWER 84
6-CYLINDER
PRESS TO
ANSWER U.S.A.
PRESS TO
ANSWER CANADIAN
ADAPTER
\
ADAPTER
4-CYLINDER
NOTE: If a wrong response is entered during the request for vehicle information, the tester must be
disconnected from the battery. The tester will automatically reset itself.
The tester will repeat a request if the information requested was not received. Enter the proper
response and the tester will continue with the test procedure.
After the correct vehicle information has been entered, the tester will request the connection of the
appropriate numbered test harness to the diagnostic connector of the vehicle. Refer to location
chart.
1981 CJ
1981 Spirit/Concord
1982 J & CJ
1982 Spirit/Concord/
Eagle
1983 J & CJ
1983 Spirit/Concord/
Eagle
1984 J, CJ & XJ
1984 Eagle
Diagnostic Connectors)
Location
Engine Compartment
Under Dash
Engine Compartment
Engine Compartment
Engine Compartment
Engine Compartment
Engine Compartment
Engine Compartment
Micro Computer Unit (MCU)
Location
Engine Compartment
Under Dash Behind Right-Hand Kick Panel
Engine Compartment
Under Dash Behind Right-Hand Kick Panel
Under Dash
Under Dash Behind Right-Hand Kick Panel
Under Dash
Under Dash Behind Right-Hand Kick Panel
NOTE: If the tester does not respond after the appropriate numbered test harness has been con¬
nected, the adapter must be affixed to the tester unit. The tester will not respond to the revised
software program unless the adapter is permanently attached to the tester.
The tester will direct the technician through the diagnostic testing procedure. Information or re¬
quests will be shown on the tester display. When a request is made by the tester, the technician
must respond by pressing the appropriate touch pad (membrane key) to indicate a response. The
touch pads can also be used to indicate a YES or NO response.
‘i
4 General Information

Operating Instructions (Continued)
5. D uring the testing procedure the tester will, at some point, instruct the technician to connect a
numbered test harness to the micro computer unit (MCU) if a fault is detected or as a diagnostic
check of the MCU. Refer to location chart.
1982
1981 v j)
1981
s 13
\ 4 v-- ~f/\ ;
||
1
1983 & 1984 Y\ ^ TTv ® •/
lWpf\ 1982, 1983 & 1984
\\ I) Jy
TEST HARNESS
CONNECTORS FOR TEST HARNESS CONNECTORS
DIAGNOSTIC CONNECTORS MICRO COMPUTER
6. When all connections are properly made, the tester will continue through the testing procedure.
IMPORTANT: All resistance tests must be performed with the ignition switch off. Always discon¬
nect the diagnostic harness from the tester before disconnecting the battery cables.
NOTE: Information, questions, or requests to perform an operational step will be communicated
through the tester’s display.
When a question is displayed, the service technician must respond by pressing the touch pad
under the appropriate answer as it appears on the display.
If a fault is indicated by the tester, verify and reverify with the tester before proceeding with a repair
of the component.
During the testing procedure if a component fault is indicated (e.g. CK CSW CKT), the service
technician will check that component fault with the procedure specified in this Instruction Manual,
repair or replace if faulty, and verify repair with the tester. If no fault is found, refer to the technical
service manual for detailed troubleshooting.
7. If an operation requested by the tester has been performed and the tester continues to display the
same message, indicate the operation has been completed by pressing the YES (left) touch pad.
This is usually a symptom of a fault, as the tester has not seen any indication from the vehicle that
the operation has been completed.
8. When the tester has completed the CEC FFB System testing, the tester will display “PASS TEST.”
General Information 5

General Information
DEFINITION OF TESTER DISPLAYS
Due to the limited amount of space on the tester display, many of the test requests and messages are ab¬
breviated to short form statements by means of key words or letters to represent a longer statement.
The complete statements are defined in the following listing.
KEY ON — Turn the ignition key to the ON position. ,
CK GND + PWR FEED — Check the system ground and power source.
NO D.C. SOL — No duty cycle pulses — check the duty cycle line.
START VEH — Start engine.
GK RPM SIGNAL — Check RPM (tach) wire with the engine off.
TESTING — Tester is testing.
CK INPUT CKTS — Check the six input circuits.
CK IDLE CKT — Check the idle circuit.
TURN KEY OFF — Turn the ignition key to the OFF position.
RP PCV SOL — Repair the positive crankcase ventilating solenoid.
RAP MANIFOLD — Tap on the manifold with a screwdriver to simulate an engine knock.
CK KNOCK CKT — Check the knock circuit.
DIS VSA — Disconnect the vacuum switch assembly.
RP VSA — Repair the vacuum switch assembly.
YES OK? NO — A yes or no response is needed for the previous display.
FLOOR IT ONCE — Push accelerator pedal to the wide-open throttle position and release immediately.
LET IDLE — Lift foot from accelerator and let the engine idle.
PASS TEST — The CEC FFB system is O.K. Test is completed.
RETEST? — Do you want to retest?
CK AIR MGMT SYS — Check the air management system.
MCU OK — The MCU is O.K.
MCU DEFECTIVE — The MCU is defective. Replace the MCU and retest.
CK CSW CKT — Check the coolant switch circuit.
CK TES CKT — Check the thermal electric switch circuit.
CK ALT CKT — Check the altitude jumper wire circuit.
CK WOT CKT — Check the wide-open throttle switch circuit.
6 General Information

Definition of Tester Displays (Continued)
CON ADAPTER — Connect the adapter permanently.
RP .. .OVER RICH — Repair an over rich condition.
RP.. .OVER LEAN — Repair an over lean condition.
/
CK VSA — Check the vacuum switch assembly.
FLOOR IT & HOLD — Press the accelerator pedal to the wide-open throttle position and hold it there.
REL ACL — Lift foot from the accelerator pedal.
WAIT.. .WARM UP — Allow the engine to warm to normal operating temperature before proceeding.
CON HRN 3-RED — Connect test harness number 3-red to the diagnostic connectors.
CON HRN 5 — Connect test harness number 5 to the MCU.
DO CLD LOOP TEST — Perform closed loop test.
HOLD. . .1500-2200 — Maintain an engine speed between 1500 and 2200 rpm.
DIS HRN 3-RED — Disconnect test harness number 3-red from the diagnostic connectors.
CON HRN 3-BLUE — Connect test harness number 3-blue to the diagnostic connectors.
CK CHOKE & FEED — Check the choke and power source.
INC RPM + 2500 — Increase engine speed above 2500 rpm and maintain.
DGN TEST MCU — Is this going to be a diagnostic test or an MCU test?
YES ALT VEH NO — Is this vehicle equipped with an altitude jumper wire?
USA CANADA — Is this vehicle manufactured per U.S. or Canadian standards?
YES SEC AIR NO — Does this Canadian vehicle have secondary air management?
CK CTS & CHOKE — Check the closed throttle switch and the choke.
DIS CTS — Disconnect the closed throttle switch.
DIS WOT — Disconnect the wide-open throttle switch.
CK CTS/WOT CKT — Check the closed throttle switch/wide-open throttle switch circuit.
CK CTS CKT — Check the closed throttle switch circuit.
RP WOTSW — Repair the wide-open throttle switch.
CON HRN 1 — Connect test harness number 1 to the diagnostic connector.
CON HRN 2 — Connect test harness number 2 to the MCU.
1981 YEAR 1982 — What model year is this vehicle?
1983 YEAR 1984 — What model year is this vehicle?
General Information 7

Definition of Tester Displays (Continued)
CK STP MOT — Check the stepper motor.
DIS VAC TO DISTB — Disconnect the vacuum hose from the distributor advance unit.
CON HRN 4 — Connect test harness number 4 to the MCU.
CON VAC TO DISTB — Connect the vacuum hose to the distributor advance unit.
DO UIM SYS TEST — Perform a universal ignition module system test.
HOLD RPM — Maintain a specified engine speed.
CK PCV SYS — Check the positive crankcase ventilating system.
AUTO TRAN MAN — Is this vehicle equipped with an automatic or manual transmission?
CK OPSW & CHOKE — Check the oil pressure switch and the choke.
INC RPM + 2400 — Increase engine speed above 2400 rpm and maintain.
SHIFT TO DRIVE — Place the transmission lever in the drive position.
SHIFT TO PARK — Place the transmission lever in the park position.
SET PARK BRAKE — Activate the emergency brake pedal/handle so the vehicle will not move.
8 General Information

6-CYLINDER
FLOW CHARTS

DO UIM TEST — Perform Electronic Ignition Retard Test
Test for 82 6-cyl.
NOTE: Engine should be at normal
6-Cylinder 2