Lofa MC536 Operating instructions

LOFA MC536 Operation and Troubleshooting
Revision - A - 22-May-2006 1
Introduction
This document provides general information on LOFA Industries MC536 control systems operation and
troubleshooting. MC536 control systems are a very flexible platform for diesel engine control, monitoring,
and protection, featuring LOFA’s powerful First Fault Diagnostics (FFD). After pinpointing the initial failure,
FFD stores it in memory and alerts the end user via a single bright LED. FFD monitors battery charge, low oil
pressure, high temperature, overspeed and up to two additional contact closure inputs. The field
configurable microprocessor-based solid-state design uses high-power semiconductors instead of outdated
electromechanical relays to ensure reliable high-current switching.
The MC536 is field configurable with an inexpensive programmer. Some of the MC536 configurable
features include:
•Automatic preheat duration
•Failure indication with shutdown or indication only
•Starter motor protection
•Over-speed shutdown
•Normally open or normally closed shutdown switches
The standard system includes a 12 inch wiring harness terminating into a sealed weatherproof plug. This
durable connection performs well in harsh environments and provides efficient installation of custom plug-
and-play engine harnesses as well as standard harness extensions.
Warning
When replacement parts are required, LOFA Industries recommends using replacement parts
supplied by LOFA or parts with equivalent specifications.
Failure to heed this warning can lead to premature failure,
product damage, personal injury or death.

LOFA MC536 Operation and Troubleshooting
2 Revision - A - 22-May-2006
Important Safety Information
The warnings in this publication are not all inclusive.
LOFA Industries cannot anticipate every potential hazard.
Appropriate safety rules and precautions should be followed with any
tool, work method or operating procedure.
Improper procedures, tools and materials may cause
damage or make the equipment unsafe to operate.
Only persons with appropriate training, skills and tools
should perform these functions.
Improper operation, maintenance or repair of this product can be
dangerous and may result in injury or death.
Do not operate or perform any maintenance or repair on this product until all operation,
maintenance and repair information is read and understood.
The information, specifications, and illustrations in this publication are based on information
available at the time of publication.
All items are subject to change at any time without notice.

LOFA MC536 Operation and Troubleshooting
Revision - A - 22-May-2006 3
Operation
Turning the control system key to the run position starts a self-test which causes all LEDs to flash three times
and enables the fuel run/stop solenoid output. After self-test, the LEDs indicate the state of the inputs they
monitor. The normal indications are battery charge and oil pressure on most applications. If these LEDs are
not illuminated at this time it may indicate the inputs are not properly connected.
The Preheat LED is illuminated when the key switch is turned to the run position if automatic preheat is
configured (See Preheat Options). Preheat time varies from application to application. After waiting for the
Preheat LED to extinguish, the engine is cranked by turning and holding the key switch in the start position
until the engine starts. The key switch is spring loaded to return automatically to the run position when
released. The Preheat LED is illuminated during afterglow if enabled.
Note
The key switch is equipped with a mechanical start locking device.
An attempt to re-crank the engine can only be made by turning the key switch
to the off position to reset the start locking mechanism.
If the engine is not started within 30 seconds of turning on the system, the fuel run/stop solenoid output is
turned off to prevent battery discharge when the key switch is left in the run position. The fuel run/stop
solenoid output is turned off after 30 seconds even if preheating. As soon as the key switch is turned to the
start position the solenoid output is enabled. The afterglow cycle begins when the key switch returns to the
run position.
Note
If conditions do not warrant preheat, the engine may be started by turning the key to the start
position without waiting for the preheat time to expire.
Control system instrument power, including the hourmeter and voltmeter, is provided by the fuel run/stop
solenoid output. If the instruments do not power up when the key is turned to the run position, this indicates
a problem with the solenoid circuit (see Troubleshooting).
After the engine starts, the control system electronics ignore all shutdown conditions for the first 10 seconds.
This delay eliminates the requirement to hold a by-pass override button during starting and allows the system
conditions such as oil pressure to normalize. The 10 second timer starts when the key switch returns to the
run position.
Note
Starter input is required for correct system operation. If the starter motor input is not activated
(connected to battery positive) and the engine is started through another means (i.e. air
starter) the engine will shutdown 30seconds after the key switch is turned to the run position.
To prevent unintentional engine shutdowns caused by intermittent conditions (i.e., pressure spikes, coolant
movement) the control system requires a constant 1/3 seconds fault input to cause engine shutdown.
Warning
When used in combination with mechanical float type switches
engine vibrations may prevent constant contact closure.

LOFA MC536 Operation and Troubleshooting
4 Revision - A - 22-May-2006
See MC536 Programming Manual for detailed instructions.
The control system has the ability to shut down the engine for over speed. Over speed will be indicated via a
blinking Battery Charge LED. The control system senses RPM by either the frequency terminal of the
alternator or a proximity switch.
Preheat Options
Preheat Output
Preheat is a 20A positve output for control of an external power relay with predetermined preheat and
afterglow times. A relay should be selected with appropriate amperage capacity for the installed cold starting
aid (glowplug, intake air heater, etc.). Applications using multiple cold starting aids may require multiple
relays. An optional external thermistor can be use to disable preheat if the temperature is above 32° F (0°
C).
Note
Consult engine documentation when selecting cold starting aid,
power relay and heating specifications.
Indicators
Battery LED (Red)
A solidly illuminated Battery LED indicates a battery charge failure. A battery charge failure may be caused
by a faulty alternator, broken drive belt or the alternator not excited. A battery voltage reading of
approximately 14 volts on a 12 volt system (28 volts on a 24 volt system) while the engine is running
indicates the battery is charging properly. Irregular blinking of the Battery LED may indicate a failing charge
circuit. The system can be configured for battery charge failure to indicate only.
A regularly blinking Battery LED indicates the configured overspeed frequency has been exceeded. Using the
MC536 programmer the overspeed frequency can be verified, changed or disabled (see the MC536
Programming Manual for details).
Oil Pressure LED (Red)
A solidly illuminated Oil Pressure LED indicates low oil pressure failure. The control system typically senses
low oil pressure from a ground contact switch on the engine. When a sender/switch combination is used on
the engine, the marking WK generally indicates the switch terminal. This input typically expects a normally
closed switch (ground contact when oil pressure is low). A defective switch or shorting the shutdown input to
ground can cause low pressure fault indication. Additionally, when using sender/switch combinations,
swapping the WK and G terminal can cause spurious shutdowns. The system can be configured for oil
pressure failure to indicate only.
Warning
Low oil pressure is not an indication of low oil level.
For best possible protection LOFA recommends using
our solid-state oil level shutdown switch.

LOFA MC536 Operation and Troubleshooting
Revision - A - 22-May-2006 5
Note
Most shutdown switches are grounded through the switch body.
Do not use insulating sealant (i.e. Teflon tape) when installing switches.
Temperature LED (Red)
A solidly illuminated Temperature LED indicates high engine temperature failure. The control system typically
senses high temperature from a ground contact switch on the engine. When a sender/switch combination is
used on the engine, the marking WK or W generally indicates the switch terminal. This input typically expects
a normally open switch (ground contact when engine temperature is too high). A defective switch or shorting
the shutdown input to ground can cause over temperature fault indication. Additionally, when using
sender/switch combinations, swapping the WK or W and G terminal can cause spurious shutdowns. The
system can be configured for temperature failure to indicate only.
Warning
If the temperature sensor is not in contact with coolant due to
coolant loss the engine is not protected from overheating.
For best possible protection, LOFA recommends using
our solid-state coolant level shutdown switch.
Note
Most shutdown switches are grounded through the switch body.
Do not use insulating sealant (i.e. Teflon tape) when installing switches.
Some thermostat housings are composites and do not provide ground for the switch.
AUX LED (Red)
A solidly illuminated AUX LED indicates auxiliary 1 failure (i.e., coolant level, oil level, belt breakage,
hydraulic pressure, etc.). The control system typically senses failure using a ground contact switch. Auxiliary
inputs are equipment specific and determined by the equipment manufacturer. A defective switch or shorting
the shutdown input to ground can cause fault indications. The system can be configured for auxilary 1 failure
to indicate only.
A blinking AUX LED indicates auxiliary 2 failure (i.e., coolant level, oil level, belt breakage, hydraulic
pressure, etc.). The control system typically senses failure using a ground contact switch. Auxiliary inputs are
equipment specific and determined by the equipment manufacturer. A defective switch or shorting the
shutdown input to ground can cause fault indications. The system can be configured for auxilary 2 failure to
indicate only.
Preheat LED (Yellow)
A solidly illuminated Preheat LED is the system preheat indication. When the LED extinquishes the preheat
period is complete and the engine may be cranked. The LED illuminates again to indicate afterglow.
OK LED (Green)
A blinking green OK LED is the fuel run/stop solenoid is enabled and the control system is ready. The LED
changes to solid illumination when the engine starts.

LOFA MC536 Operation and Troubleshooting
6 Revision - A - 22-May-2006
Gauges
Voltmeter
The voltmeter is connected to the fuel run/stop solenoid output. If the voltemeter does not indicate in the run
position, this indicates a problem with the solenoid circuit. A battery voltage reading of approximately 14
volts on a 12 volt system (28 volts on a 24 volt system) while the engine is running indicates the battery is
charging properly.
Tachometer
The tachometer indicates engine RPM using a frequency signal derived from the engine. This signal may be
provided by an alternator frequency tap or proximity switch.
Note
If the alternator is not excited (not charging),
no frequency is generated and the tachometer will indicate 0 RPM.
The tachometer must be calibrated to accurately indicate RPM (see Tachometer Calibration Instuctions for
details).
Oil Pressure Gauge
The gauge measures oil pressure with a resistance sender on the engine referenced to ground. When a
sender/switch combination is used on the engine, the marking Ggenerally indicates the gauge terminal. The
gauge expects a low resistnace for low pressure and a higher resitance for higher pressure. If the gauge is
not connected to the sender, the gauge will read full scale (pegged). A defective sender or shorting the
gauge input to ground will cause the gauge to read 0 pressure. When using sender/switch combinations,
swapping the WK and G terminal prevents the gauge from working and may cause spurious shutdowns.
Warning
Low oil pressure is an indication of engine wear,
not an accurate indication of low oil level.
Note
Senders and gauges must be matched to each other.
Improperly matched gauge/senders will not indicate correctly.
Most senders are grounded through the sender body.
Do not use insulating sealant (i.e. Teflon tape) when installing senders.
Temperature Gauge
The gauge measures engine temperature with a resistance sender on the engine referenced to ground.
When a sender/switch combination is used on the engine, the marking Ggenerally indicates the gauge
terminal. The gauge expects a high resistnace for low temperatures and a lower resitance for higher
temperatures. If the gauge is not connected to the sender, the gauge will read 0. A defective sender or
shorting the gauge input to ground will cause the gauge to read fulle scale (pegged). When using
sender/switch combinations, swapping the WK and G terminal prevents the gauge from working and may
cause spurious shutdowns.

LOFA MC536 Operation and Troubleshooting
Revision - A - 22-May-2006 7
Warning
If the temperature sensor is not in contact with coolant due to coolant loss
the gauge will not accurately indicate engine temperature.
Note
Senders and gauges must be matched to each other.
Improperly matched gauge/senders will not indicate correctly.
Most senders are grounded through the sender body.
Do not use insulating sealant (i.e. Teflon tape) when installing senders.
Some thermostat housings are composites and do not provide ground for the sender.
Hourmeter
The houmeter is connected to the fuel run/stop solenoid output. If the hourmeter does not count in the run
position, this indicates a problem with the solenoid circuit. If the engine shutsdown or is not started within 30
seconds the hourmeter stops counting.
Additional Gauges
Additional gauges can be added by removing blind covers and installing the gauge. Power connections are
provided.
Harness
The provided sealed weather proof plug includes a grey locking device which must be released to separate
the connectors. Press the tab on the connector housing to release the connectors.
Warning
LOFA does not recommend using dielectric grease or sealant.
These chemicals may cause seal damage and allow water entry.
Use LOFA provided cavity plugs to reseal the connector if wires are removed.
The minimum routing of radius of the wiring harnesses should be at least two times the diameter of the
wiring harness. Bends should be avoided within 1 inch (25 mm) of any connector in order to avoid seal
distortion allowing moisture to enter the connector.

LOFA MC536 Operation and Troubleshooting
8 Revision - A - 22-May-2006
Battery Circuit Requirements
Battery Positive Connection
The electronic control system operates on either a 12 VDC or 24 VDC electrical systems. The unswitched
battery positive connection to the control system is made at the weather proof connector. The control system
provides switched positive battery
Protection for the unswitched battery positive circuit is dependent on specific equipment configuration. The
overload protection should not exceed 125% of the sum of all output currents plus 5 Amps for the control
system. Powering the control system through dedicated circuits with appropriate overload protection reduces
the possibility of system damage.
Circuit breakers are preferred over in-line fuses for circuit protection. Over current protection devices should
ideally be located in a central location. If automatic reset circuit breakers are used, consideration of the
environment of the breaker is critical and may affect the trip point. The trip point of some circuit breakers
can be significantly reduced below the rated trip point if the circuit breaker is exposed to high temperatures.
Warning
Disconnecting the battery while the engine is running
may damage electrical components.
When using a battery disconnect switch, LOFA recommends using a
2 pole switch to disconnect both the battery and alternator output.
Battery Negative Connection (Grounding)
Warning
Improper grounding can cause electrical noise, unreliable operation and may damage the
control system or other components. All ground connections must be free from foreign
materials, including paint, which may interfere with proper grounding.
A reliable ground must be provided for the control system.
LOFA recommends the ground connection be made directly to the battery negative.
Grounding through frame members is not recommended.
All ground paths must be capable of carrying any likely fault currents.
Do not reverse the battery polarity. Attempting to crank the engine when the polarity of the
battery connections is reversed may damage the control system.
Note
A maximum of three ring terminals should be connected to a ground stud in order to ensure
integrity of the ground connection. The use of more than three terminals can cause the
connection to become loose.
Voltage Drop
If control system voltage drops below 6 volts for more than one tenth of a second, the control system may
reset causing the self test to reactivate and the engine to shutdown after 10 seconds. Resetting the control

LOFA MC536 Operation and Troubleshooting
Revision - A - 22-May-2006 9
system is equivalent to quickly turning the key switch to off and back to run without starting the engine. Since
the control system did not sense a start signal, the fuel run/stop solenoid deactivates after 10 seconds.
Voltage drops can be caused by transients from external equipment, improper wire sizes, faulty wiring or
nearby lightning strikes. In the absence of a LOFA Power Box, relays may be needed for long wire runs.
Suppression of Voltage Transients (Spikes)
Warning
The installation of voltage transient suppression at the transient source is required.
LOFA follows SAE recommended electrical environment practices.
Inductive devices such as relays, solenoids and motors generate voltage transients and noise in electrical
circuits. Unsuppressed voltage transients can exceed SAE specifications and damage electronic controls.
I
Relays and solenoids with built-in voltage transient suppression diodes are recommended whenever possible.
Refer to the illustration for proper installation of diodes when built-in voltage transient suppression is not
available.
Locate inductive devices as far as possible from the components of the electronic control system. When
using electric motors it may also be necessary to add isolation relays to eliminate voltage transients, noise
and prevent back feed.
Note
LOFA Power Box harness assemblies include all required engine control suppression devices.
Added equipment will require additional protection.

LOFA MC536 Operation and Troubleshooting
10 Revision - A - 22-May-2006
Welding on Equipment with Electronic Controls
Proper welding procedures are required to avoid damage to electronic controls, sensors, and associated
components. The component should be removed for welding if possible.
The following procedure must be followed if the component must be welded while installed on equipment
with electronic controls. This procedure will minimize the risk of component damage.
Warning
Do not ground the welder to electrical components such as the control ground or sensors.
Improper grounding can cause damage to electrical components
Clamp the ground cable from the welder to the component being welded. Place the clamp
as close as possible to the weld to reduce the possibility of damage.
1. Stop the engine. Turn the key switch to the OFF position.
2. Disconnect the negative battery cable from the battery.
3. Open any installed battery disconnect switch.
4. Unplug the control system if possible.
5. Connect the welding ground cable as close as possible to the area to be welded.
6. Protect the wiring harness from welding debris and spatter.
7. Use standard welding methods to weld the materials.

LOFA MC536 Operation and Troubleshooting
Revision - A - 22-May-2006 11
General Troubleshooting
For additional information, refer to engine manufacturer troubleshooting guide.
No response from starter motor
Possible Cause Possible Remedy
No battery voltage to starter Verify wiring and battery connection (power and ground)
Battery discharged Charge or replace battery, verify alternator charging
Tripped overcurrent protection Correct fault, replace or reset overcurrent protection
No signal from control system No power to control system (see Control System Troubleshooting below)
Defective starter solenoid Replace starter solenoid
Defective starter motor Replace starter motor
Engine will crank but not start
Possible Cause Possible Remedy
Engine not getting fuel Check fuel level, filter, fuel pump, verify no air in fuel lines
Fuel run/stop solenoid not
engaged
See Fuel Solenoid Run/Stop Troubleshooting (below)
Tripped overcurrent protection Correct fault, replace or reset overcurrent protection
No preheat (cold condition) See Preheat Troubleshooting
Engine runs for 10 seconds and shuts down
Possible Cause Possible Remedy
Shutdown switch input active Verify shutdown source exists, correct condition or correct faulty circuit
Battery not charging Verify alternator charging (see Alternator not charging battery below)
Control board did not sense
start signal
Engine started through alternate method (i.e., manual air start, push start,
etc.)
Defective control system See Control Panel Troubleshooting (below)
Engine runs longer than 10 seconds and shuts down
Possible Cause Possible Remedy
Shutdown switch input active Correct engine fault, verify shutdown switch wiring
Circuit overload protection
tripped
Correct overload, keep control system from overheating
(over 185° F/85° C)
Voltage transients (spikes) Add suppressor diodes, protect from nearby lightening strikes, shield
induced spikes from other equipment, add electric motor control relay
Defective control system See Control System Troubleshooting (below)
Alternator not charging battery
Possible Cause Possible Remedy
Broken or slipping alternator
drive belt
Adjust or replace alternator drive belt
Alternator not excited Verify excitation circuit connected, replace faulty regulator
Alternator output not
connected
Install charge wire
Alternator not grounded Clean or add ground connection
Alternator faulty Replace faulty alternator

LOFA MC536 Operation and Troubleshooting
12 Revision - A - 22-May-2006
Fuel Run/Stop Solenoid Troubleshooting
Engine does not stop immediately
Possible Cause Possible Remedy
Back feed from motor (i.e.,
cooling fan)
Add relay or blocking diode
Sticking solenoid linkage Repair or replace solenoid linkage
Fuel valve without check valve Install or repair check valve
Fuel run/stop solenoid does not engage
Possible Cause Possible Remedy
No power to solenoid Locate reason for lack of power and correct (Circuit overloaded? Failed
suppressor diode? Faulty wiring?)
No power to solenoid pull coil Correct faulty wiring, check pull control circuit (see Power Box
Troubleshooting below)
Incorrect linkage adjustment Adjust solenoid linkage
Faulty solenoid Replace solenoid
Failed suppressor diode Correct wiring (diode reversed?), replace suppressor diode
Optional e-stop engaged Disengage e-stop
Engine not getting fuel
Possible Cause Possible Remedy
Empty fuel tank Fuel engine
Clogged filter Replace filter
Air in fuel lines Bleed fuel lines
Low fuel pressure Replace faulty fuel pump and/or clogged filter
Faulty fuel pump Replace fuel pump, correct wiring fault (electric fuel pump)
Preheat Troubleshooting
Engine is hard to start in cold conditions
Possible Cause Possible Remedy
Start attempt before preheat
complete
Wait for preheat time to elapse, crank as soon as time elapses
Incorrect preheat specification Correct control system configuration, install correct control system
Heater faulty Replace heater
Heater relay faulty Replace relay
Preheat control not functioning Correct wiring, correct control system configuration
Faulty control system See Control System Troubleshooting (below)
Engine produces excessive white smoke after starting
Possible Cause Possible Remedy
Afterglow not enabled Reconfigure control system
Heater faulty Replace heater
Heater relay faulty Replace relay
Preheat control not functioning Correct wiring, correct control system configuration
Faulty control system See Control System Troubleshooting (below)

LOFA MC536 Operation and Troubleshooting
Revision - A - 22-May-2006 13
Control System Troubleshooting
Control system does not perform self test
Possible Cause Possible Remedy
Tripped overcurrent protection Correct fault, replace or reset overcurrent protection
Faulty connection to battery Correct battery connections (see Battery Circuit Requirements above)
Control system performs normal self test, engine cranks, runs and shuts down
Possible Cause Possible Remedy
Only Battery LED illuminated Correct battery charge failure (see Battery not charging above)
Only Oil Pressure LED
Illuminated
Correct low oil pressure condition or faulty switch, correct wiring fault
Only Temperature LED
Illuminated
Correct overheating condition or faulty switch, correct wiring fault
Only Aux LED Illuminated Correct fault condition (i.e. coolant level) or faulty switch, correct wiring
fault
All normally closed shutdowns
illuminate for one second
(control system reset)
Add suppressor diodes, protect from nearby lightening strikes, shield
induced spikes from other equipment, add electric motor control relay
Testing Shutdown Inputs
Shutdown switches signal a fault by ground contact in most systems. Shutdown operation can be verified by
grounding the shutdown inputs individually. It may be necessary to remove the wire from the shutdown
switch to perform this test.
Note
Most shutdown switches are grounded through the switch body.
Do not use insulating sealant (i.e. Teflon tape) when installing switches.
Some thermostat housings are composites and do not provide ground for the switch.

LOFA MC536 Operation and Troubleshooting
14 Revision - A - 22-May-2006
Power Box Operation
The Power Box is a solid state, high current control system for mechanically governed, industrial diesel
engines. In addition to allowing extended harnesses, the Power Box provides 3-wire fuel run/stop solenoid
control to protect the pull coil from overheating. Power Box technology typically controls the starter solenoid,
fuel run/stop solenoid and cold starting aid. All outputs are overload protected and the system is fused to
avoid damage in the event of excess current demand. An additional fuse protects the control circuitry.
Warning
The Power Box is reverse polarity protected but may be damaged by attempting to start the
engine with battery polarity reversed.
When the fuel solenoid input is enabled, the fuel run/stop solenoid pull coil is enabled for the first second. In
normal operation, all other Power Box outputs are active as long as their corresponding inputs are active.
Power Box Troubleshooting
One output never activates
Possible Cause Possible Remedy
Input not active See Control System Troubleshooting (above)
Output shorted Correct fault
Failed Power Box Replace Power Box/harness assembly
All outputs never activate
Possible Cause Possible Remedy
Blown fuse(s) Correct fault, replace fuse(s)
Faulty connection to battery Correct battery connections (see Battery Circuit Requirements above)
Failed Power Box Replace Power Box/harness assembly
Fuel run/stop solenoid pull output remains active
Possible Cause Possible Remedy
Faulty wiring Correct wiring
Faulty connection to battery Correct battery connections (see Battery Circuit Requirements above)
Failed Power Box Replace Power Box/harness assembly
Revision History
Initial Release.
Rev A – 22-May-2006. Corrected typographical errors.

LOFA MC536 Operation and Troubleshooting
Typical Schematics
The following pages show typical schematics.
Details vary from installation to installation.
See the specific schematics for installation for details.
Revision - A - 22-May-2006 15

LOFA MC536 Operation and Troubleshooting
Description:
Part Number:
250 Hembree Park Dr Ste 122
Rev Drawn By: Date:
Roswell GA 30076 phone: [phone] fax: [phone]
Tolerances
+/- .X .XX .XXX ANGº
.1 .02 .005 2º
Sheet of
www.LOFA.net
MANUFACTURER OF QUALITY ENGINE COMPONENTS
INDUSTRIES, INC.
MC536G7A Point to Point with AutoStart
MThiam 02-08-06 11
P2
Male To Male White
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
P1
Male To Male Yellow
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
J38
White 8 Pos
1
2
3
4
5
6
7
8
J37
Yellow 8 Pos
1
2
3
4
5
6
7
8
D+ Alternator
Battery (30)
Starter (50)
Preheat Control
Ground
Ground
Solenoid
Temp Switch
Temp Gauge
Aux Switch 2
Tachometer
Ground
Pressure Switch
Pressure Gauge
Preheat Control
Starter (50)
Battery (30)
D+ Alternator
Solenoid
Tachometer
Aux Switch 2
Temp Gauge
Temp Switch
Pressure Gauge
Pressure Switch
Ground
J35
KeySwitch
6 Pos.
5
6
7
8
9
10
J36
KeySwitch
4 Pos.
1
2
3
4
16 AWG Green
16 AWG White
16 AWG Yellow
16 AWG Yellow/Blue
16 AWG Yellow/Black
16 AWG Yellow/Orange
16 AWG Blue Aux Switch 1
12 AWG Red
Aux Switch 1
Ground
Ground
THE INFORMATION CONTAINED IN THIS DRAWING IS CONFIDENTIAL AND THE SOLE PROPERTY OF LOFA INDUSTRIES INC. Reproduction or dissemination in whole or in part in any form or medium without express prior written permission of LOFA INDUSTRIES INC is prohibited.
14 AWG Red/Black
12 AWG Red/Black
14 AWG Red
12 AWG Red
J27 6.3mm PosLock
J28 6.3mm PosLock
J29 6.3mm PosLock
J31 6.3mm PosLock
0000
G5
Hourmeter
-+
G6
+
+
-
-
G4
Pressure +
+
-
-
G3
+
+
-
-
G7Fuel
Level +
+
-
-
16 AWG Black
16 AWG Black
16 AWG Red
16 AWG Black 16 AWG Black 16 AWG Black 16 AWG Black
16 AWG Red 16 AWG Red 16 AWG Red 16 AWG Red
G1
Voltmeter
-+
J18
6.3mm PosLock
J20
6.3mm PosLock
J23
6.3mm PosLock
FLT1
FLT2 J17
6 Pos. Black
1
2
3
4
5
6
16 AWG Black
16 AWG Tan
16 AWG Black
16 AWG Grey
J22
6.3mm PosLock
J21
6.3mm PosLock
J34
JPT 14 POS
FEMALE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
J13
6.3mm PosLock
J19
6.3mm PosLock
J8
6.3mm PosLock
J5 6.3mm PosLock
J2
6.3mm PosLock
J4
6.3mm PosLock
J7
6.3mm PosLock
J10
6.3mm PosLock
J12
6.3mm PosLock
J15
6.3mm PosLock
J3
6.3mm PosLock
J6
6.3mm PosLock
J9
6.3mm PosLock
J11
6.3mm PosLock
J14
6.3mm PosLock
J16
6.3mm PosLock
J256.3mm PosLock
J266.3mm PosLock
J30 6.3mm PosLock
KS1
KeySwitch
15
15
50A
19
19
58 30
30
17
17
J32 6.3mm PosLock
14 AWG Black
14 AWG Black
J33 6.3mm PosLock
16 AWG Red
J1
6.3mm PosLock
16 AWG Red
Programming
Connector
MC-536
1
2
3
4
5
6
7
8
9
10
11
12
13
14
50f
50e
W
Temp
Oel (PSI)
Tachometer
Aux Switch 1
Temp Switch
Aux Switch 2
Pressure Switch
Ground
Ground
Accessory (15)
Accessory (15)
Preheat Control
Solenoid
Pressure Gauge
Temp Gauge
D+ Alternator
Alm
Kl.31 (Gnd)
Gen (D+)
Mag (Sol)
ext. Stop
15
15
30
15a
Running Battery PSI Temp Aux 1&2 Prh
J16
Circuit Board
30
Kl.31 (Gnd)
VG (Preheat)
BD1
J24
6.3mm PosLock 16 AWG Red/White
MSS200
INTERFACE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1
2
3
4
5
6
2
3
X10
1
X6
X7
30
31
31
30
50f
58
K1-30
K1-87a
31
K1-87
k1-87
K1-85
K4-87
K4-87a
D+
W-G
19-17
Sol+
X9
X4
X3
X5
D+ Alternator
Thermistor
Tachometer
Ground
AutoStart
Ground
Alarm
Pressure Switch
Auto Power (58)
Pressure Switch
Preheat Control
Starter (50)
Solenoid
X1 1
2
3
4
X11
Aux Relay
Sol2 X8
G2
14 AWG Black
16 AWG Tan
14 AWG Red
J266.3mm PosLock
14 AWG Purple
J266.3mm PosLock
16 AWG Black
J34
Relay Connector
30 85 86 87 87a
CR1
Relay 30A
With Diode
16 AWG Orange
16 AWG Brown
14 AWG Red/Black
14 AWG Red
16 AWG Black
14 AWG Pink/Black
16 Revision - A - 22-May-2006

LOFA MC536 Operation and Troubleshooting
Description:
Part Number:
250 Hembree Park Dr Ste 122
Rev Drawn By: Date:
Roswell GA 30076 phone: [phone] fax: [phone]
Tolerances
+/- .X .XX .XXX ANGº
.1 .02 .005 2º
Sheet of
www.LOFA.net
MANUFACTURER OF QUALITY ENGINE COMPONENTS
INDUSTRIES, INC.
MC-536 Generic Engine Schematic W/ Yellow And White Connectors
MThiam 11
CR1
Power
Relay
87a
30
85
86
87
BAT1
Battery
TS1
Temperature
Sender/Switch
WK G
PS1
Oil Pressure
Sender/Switch
WK G
Preheat
Unit
Ground
SOL3
Shutdown
Solenoid
Red 12 AWG To P1/P
N./O. N./C.
ALT1
Bosch Alternator
D+ B+ W
MOT1
Starter Motor
30 50
31
12B+ RIG LB+
R
Pull
Hold
3 Wire Solenoid
Wiring Diagram
Kubota Alternator
Wiring Diagram
Delco Alternator
Wiring Diagram
14 AWG Purple To P1/H
Note: -WK = Switch
-G = Gauge
SW1
Aux 1
Shutdown
J2
8 Pos White
1
2
3
4
5
6
7
8
J1
8 Pos Yellow
1
2
3
4
5
6
7
8
CB1
SW1
Aux 2
Shutdown
Indication Only
Tachometer
Aux Switch 1
Temp Gauge
Temp Switch
Pressure Gauge
Pressure Switch
Ground
Preheat Control
Starter (50)
Battery+ (30)
D+ Alternator
Solenoid
Aux Switch 1
16 AWG White
16 AWG Yellow/Black
16 AWG Blue
16 AWG Yellow/Blue
16 AWG Orange
16 AWG Yellow/Orange
16 AWG Tan
12 AWG Red/Black
12 AWG Red
16 AWG Green
14 AWG Purple
8 AWG Red 8 AWG Red
16 AWG Yellow
THE INFORMATION CONTAINED IN THIS DRAWING IS CONFIDENTIAL AND THE SOLE PROPERTY OF LOFA INDUSTRIES INC. Reproduction or dissemination in whole or in part in any form or medium without express prior written permission of LOFA INDUSTRIES INC is prohibited.
16 AWG Black
Revision - A - 22-May-2006 17

LOFA MC536 Operation and Troubleshooting
THE INFORMATION CONTAINED IN THIS DRAWING IS CONFIDENTIAL AND THE SOLE PROPERTY OF LOFA INDUSTRIES INC. Reproduction or dissemination in whole or in part in any form or medium without express prior written permission of LOFA INDUSTRIES INC is prohibited.
16 AWG Black
16 AWG Black
16 AWG Red
16 AWG Black 16 AWG Black 16 AWG Black 16 AWG Black
16 AWG Red 16 AWG Red 16 AWG Red 16 AWG Red
G1
Voltmeter
-+
J18
6.3mm PosLock
J20
6.3mm PosLock
J23
6.3mm PosLock
FLT1
FLT2 J17
6 Pos. Black
1
2
3
4
5
6
16 AWG Black
16 AWG Tan
16 AWG Black
16 AWG Grey
J22
6.3mm PosLock
J21
6.3mm PosLock
MSS200
INTERFACE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1
2
3
4
5
6
2
3
X10
1
X6
X7
30
31
31
30
50f
58
K1-30
K1-87a
31
K1-87
k1-87
K1-85
K4-87
K4-87a
D+
W-G
19-17
Sol+
X9
X4
X3
X5
D+ Alternator
Thermistor
Tachometer
Ground
AutoStart
Ground
Alarm
Pressure Switch
Auto Power (58)
Pressure Switch
Preheat Control
Starter (50)
Solenoid
X1 1
2
3
4
X11
Aux Relay
Sol2 X8
G2
14 AWG Black
16 AWG Tan
14 AWG Red
J266.3mm PosLock
14 AWG Purple
J266.3mm PosLock
16 AWG Black
16 AWG Orange
J29 6.3mm PosLock
16 AWG Yellow/Black
16 AWG Yellow/Orange
16 AWG Blue
12 AWG Red
12 AWG Red
Accessory (15)
Tachometer
D+ Alternator
Temp Gauge
Pressure Gauge
Preheat Control
Battery+ (30)
Solenoid
Aux Switch 2
Aux Switch 1
Temp Switch
Pressure Switch
Ground
Starter (50)
Mix Male
GT 150/280
A
B
C
D
E
F
G
H
J
K
L
M
N
P
P1
J34 6.3mm PosLock
14 AWG Red/Black
16 AWG Red
J1
6.3mm PosLock
16 AWG Red
Programming
Connector
MC-536
1
2
3
4
5
6
7
8
9
10
11
12
13
14
50f
50e
W
Temp
Oel (PSI)
Tachometer
Aux Switch 1
Temp Switch
Aux Switch 2
Pressure Switch
Ground
Ground
Accessory (15)
Accessory (15)
Preheat Control
Solenoid
Pressure Gauge
Temp Gauge
D+ Alternator
Alm
Kl.31 (Gnd)
Gen (D+)
Mag (Sol)
ext. Stop
15
15
30
15a
Running Battery PSI Temp Aux 1&2 Prh
J16
Circuit Board
30
Kl.31 (Gnd)
VG (Preheat)
BD1
J24
6.3mm PosLock 16 AWG Red/White
J10
6.3mm PosLock
J12
6.3mm PosLock
J15
6.3mm PosLock
J3
6.3mm PosLock
J6
6.3mm PosLock
J9
6.3mm PosLock
J11
6.3mm PosLock
J14
6.3mm PosLock
J16
6.3mm PosLock
J256.3mm PosLock
J266.3mm PosLock
J31 6.3mm PosLock
KS1
KeySwitch
15
15
50A
19
19
58 30
30
17
17
J33 6.3mm PosLock
14 AWG Red/Black
12 AWG Red/Black
14 AWG Red
12 AWG Red
Description:
Part Number:
250 Hembree Park Dr Ste 122
Rev Drawn By: Date:
Roswell GA 30076 phone: [phone] fax: [phone]
Tolerances
+/- .X .XX .XXX ANGº
.1 .02 .005 2º
Sheet of
www.LOFA.net
MANUFACTURER OF QUALITY ENGINE COMPONENTS
INDUSTRIES, INC.
MC536G7A GT Point to Point
MThiam 02-08-06 11
0000
G5
Hourmeter
-+
G6
+
+
-
-
G4
Pressure +
+
-
-
G3
+
+
-
-
G7Fuel
Level +
+
-
-
J36
KeySwitch
6 Pos.
5
6
7
8
9
10
J37
KeySwitch
4 Pos.
1
2
3
4
16 AWG Green
16 AWG White
16 AWG Yellow
16 AWG Yellow/Blue
J35
JPT 14 POS
FEMALE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
J13
6.3mm PosLock
J19
6.3mm PosLock
J8
6.3mm PosLock
J5 6.3mm PosLock
J2
6.3mm PosLock
J4
6.3mm PosLock
J7
6.3mm PosLock
J27 6.3mm PosLock
J28 6.3mm PosLock
J30 6.3mm PosLock
J32 6.3mm PosLock
18 Revision - A - 22-May-2006

LOFA MC536 Operation and Troubleshooting
Description:
Part Number:
250 Hembree Park Dr Ste 122
Rev Drawn By: Date:
Roswell GA 30076 phone: [phone] fax: [phone]
Tolerances
+/- .X .XX .XXX ANGº
.1 .02 .005 2º
Sheet of
www.LOFA.net
MANUFACTURER OF QUALITY ENGINE COMPONENTS
INDUSTRIES, INC.
MC-536 Engine Generic Diagram With GT Male
MThiam 11
CR1
Power
Relay
87a
30
85
86
87
BAT1
Battery
TAS1
Temperature
Sender/Switch
WK G
PS1
Oil Pressure
Sender/Switch
WK G
Preheat
Unit
Ground SOL3
Shutdown
Solenoid N./O. N./C.
ALT1
D+ B+ W
MOT1
30 50
31
12B+ RIG LB+ R
Pull
Hold
3 Wire Solenoid
Wiring Diagram
Note: -WK = Switch
-G = Gauge
SW1
Aux 1
Shutdown
SW2
Aux 2
Shutdown
Indicator Only
THE INFORMATION CONTAINED IN THIS DRAWING IS CONFIDENTIAL AND THE SOLE PROPERTY OF LOFA INDUSTRIES INC. Reproduction or dissemination in whole or in part in any form or medium without express priorwritten permission of LOFA INDUSTRIES INC is prohibited.
P1
Gt 14 Pos. Male
A
B
C
D
E
F
G
H
J
K
L
M
N
P
Accessory (15)
Tachometer
D+ Alternator
Temp Gauge
Pressure Gauge
Preheat Control
Battery+ (30)
Solenoid
Aux Switch 2
Aux Switch 1
Temp Switch
Pressure Switch
Ground
Starter (50)
16 AWG White
16 AWG Green
16 AWG Blue
16 AWG Orange
14 AWG Purple
16 AWG Yellow/Black
16 AWG Yellow
16 AWG Yellow/Blue
16 AWG Yellow/Orange
12 AWG Red/Black
12 AWG Red
8 AWG Red 8 AWG Red
12 AWG Red
16 AWG Tan
16 AWG Black
14 AWG Pink/Black
16 AWG Red 16 AWG Black
Revision - A - 22-May-2006 19