Kohler COMMAND CH18-745 User Manual

Page 104

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5B.45

Section 5B

EFI Fuel System

5B

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

“35 Pin” (MA 1.7) Metal-Cased ECU: Pin circuits
3 and 21
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Pin
circuits 9 and 10.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Pin
circuits 9 and 10.

3. Speed sensor/toothed wheel air gap
4. Toothed wheel
5. Flywheel key sheared
6. ECU

Diagnostic Aid #5 “FUEL PUMP” (fuel pump not
turning on)

Possible causes:

1. Fuel pump fuse
2. Fuel pump circuit problem

“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits
43, 44, and relay.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
30, 87, and relay.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
30, 87, and relay.

3. Fuel pump

Diagnostic Aid #6 “RELAY” (relay not operating)

Possible causes:

1. Safety switches/circuit(s) problem

“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 41
and 41A.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuit
3.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuit
25.

2. Relay circuit(s) problem

35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 28,
41, and 41A.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
18, 85, 30, and 87.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
28,85, 30, and 87.

3. Relay
4. ECU grounds
5. ECU

Diagnostic Aid #7 “IGNITION SYSTEM” (no spark)

Possible causes:

1. Spark plug
2. Plug wire
3. Coil
4. Coil circuit(s)

“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits 1,
19, 40, 40A, 43, and relay.
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
22, 23, 65, 66, 30, and relay.
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
30, 31, 65, 66, relay and relay circuit 30.

5. ECU grounds
6. ECU

Diagnostic Aid #8 “FUEL SYSTEM-ELECTRICAL”
(no fuel delivery)

Possible causes:

1. No fuel
2. Air in fuel rail
3. Fuel valve shut off
4. Fuel filter/line plugged
5. Injector circuit(s)

“35 Pin” (MA 1.7) Metal-Cased ECU: Circuits
35, 35A, 45, and 45A
“24 Pin” (MSE 1.0) Plastic-Cased ECU: Circuits
16, 17, 45, and 45A
“32 Pin” (MSE 1.1) Plastic-Cased ECU: Circuits
14,15, and 45.

6. Injector
7. ECU grounds
8. ECU

Diagnostic Aid #9 “FUEL SYSTEM” (fuel pressure)

Possible causes for low fuel system pressure:

1. Low fuel
2. Fuel filter plugged
3. Fuel supply line plugged
4. Pressure regulator
5. Fuel pump

Possible causes for high fuel system pressure:

1. Pressure regulator
2. Fuel return line plugged or restricted.

Diagnostic Aid #10 “BASIC ENGINE” (cranks but will
not run)

Possible causes:

1. Refer to basic engine troubleshooting charts

within service manual sections 3, 5, and 8.

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