Flow Chart Diagnostic Aids - Kohler LH630-775 Service Manual

Flow Chart Diagnostic Aids

Diagnostic Aid #1 "SYSTEM POWER" (MIL does not
illuminate when key is turned "on")
Possible causes:
1. Battery
2. Main system fuse
3. MIL light bulb burned out
4. MIL electrical circuit problem. Pin circuits 29
and 84.
5. Ignition switch
6. Permanent ECU power circuit problem. Pin
circuit 1.
7. Switched ECU power circuit problem. Pin circuit
2.
8 ECU grounds
9. ECU
Diagnostic Aid #2 "FAULT CODES" (Refer to detailed
fault code listing before flow chart and "servicing"
information for the respective components)
1. Code 21 - Engine Speed Synchronization
2. Code 22 - Throttle Position Sensor (TPS)
3. Code 23 - Engine Control Unit (ECU)
4. Code 31 - Oxygen Sensor
5. Code 32 - Oxygen Sensor
6. Code 33 - Fuel System (temporary adaptation
factor)
7. Code 34 - Fuel System (permanent adaptation
factor)
8. Code 42 - Engine (Coolant) Temperature Sensor
9. Code 43 - TPS "Auto-Learn" Initialization
Function. (Below Min. Limit)
10. Code 44 - TPS "Auto-Learn" Initialization
Function. (Above Max. Limit)
11. Code 51 - Injector 1
12. Code 52 - Injector 2
13. Code 55 - MIL (Diagnostic Light)
14. Code 56 - Pump Relay
15. Code 61 - End of Fault/Blink Code Transmission.
Diagnostic Aid #3 "RUN/ON" (MIL remains "on"
while engine is running)*
Possible causes:
1. Fault codes which turn on MIL when engine is
running.
a. Code 21 - Engine Speed Synchronization
b. Code 22 - Throttle Position Sensor (TPS)
c. Code 23 - Engine Control Unit (ECU)
d. Code 31 - Oxygen Sensor (shorted)
e. Code 34 - Fuel System (permanent adaptation
at limit)
f. Code 42 - Engine (Coolant) Temperature
Sensor
g. Code 43 - TPS "Auto-Learn" Initialization
Function (Below Min. Limit)
h. Code 44 - TPS "Auto-Learn" Initialization
Function (Above Max. Limit)
i. Code 51 - Injector 1
j. Code 52 - Injector 2
k. Code 55 - MIL (Diagnostic Light)
l. Code 56 - Pump Relay
2. MIL circuit grounded between light and ECU. Pin
circuit 29.
3. ECU
*NOTE: The MIL (diagnostic light) used must be a 1/4
watt incandescent lamp. An LED style light
will stay on continuously (dim) and should
not be used.
Diagnostic Aid #4 "SPEED SENSOR" (MIL does not
turn off during cranking) Indicates the ECU is not
receiving a signal from the speed sensor.
Possible causes:
1. Speed sensor
2. Speed sensor circuit problem. Pin circuits 9 and
10.
3. Speed sensor/toothed wheel air gap
4. Toothed wheel
5. Flywheel key sheared
6. ECU
Section 5B
EFI Fuel System
5B.35
5B