Kohler Command CV730 User Manual download pdf (Page 101)

5B.34

Section 5B

EFI Fuel System

Code: 23

Source: ECU

Explanation: ECU is unable to recognize or process

signals from its memory.

Expected Engine

Response: Engine will not run.

Possible Causes:

1. ECU (internal memory problem).

a. Diagnosable only through the elimination of

all other system/component faults.

Code: 24 (Will not blink out)

Source: Engine Speed Sensor

Explanation: No tooth signal from speed sensor.

MIL light will not go out when

cranking.

Expected Engine

Response: None-engine will not start or run as

the ECU is unable to estimate speed.

Possible Causes:

1. Engine Speed Sensor Related

a. Sensor connector or wiring.

b. Sensor loose or air gap incorrect.

2. Speed Sensor Wheel Related

a. Damaged teeth.

b. Gap section not registering.

3. Engine Wiring Harness Related

a. Pin circuit wiring or connectors.

Pin(s) 9 and/or 10 for “24 Pin” (MSE 1.0)

Plastic-Cased ECU.

Pin(s) 9 and/or 10 for “32 Pin” (MSE 1.1)

Plastic-Cased ECU.

4. ECU/Harness Related

a. ECU-to-harness connection problem.

Code: 31

Source: Fuel Mixture or Oxygen Sensor

Explanation: “System too lean.” Oxygen sensor not

sending expected voltage to ECU.

Expected Engine

Response: System operates under “open loop”

control only. Until fault is detected

and registered by ECU, engine will

run richif oxygen sensor is shorted to

ground or lean if it is shorted to

battery voltage. After fault is detected,

performance can vary, depending on

cause. If performance is pretty good,

the problem is probably with the

oxygen sensor, wiring, or connectors.

If the engine is still running rich

(laboring, short on power) or lean

popping or misfiring), the fuel

mixtureis suspect, probably incorrect

TPS initialization or low fuel pressure.

Possible Causes:

1. TPS Initialization Incorrect

a. Lean condition (check oxygen sensor signal

with VOA and see Oxygen Sensor section).

2. Engine Wiring Harness Related

a. Pin circuit wiring or connectors.

Pin 11 for “24 Pin” (MSE 1.0) Plastic-Cased

ECU.

Pin 20 for “32 Pin” (MSE 1.1) Plastic-Cased

ECU.

3. Low Fuel Pressure

4. Oxygen Sensor Related

a. Sensor connector or wiring problem.

b. Exhaust leak.

c. Poor ground path to engine (sensor is case

grounded).

5. Poor system ground from ECU to engine, causing

rich running while indicating lean.

Code: 32

Source: Oxygen Sensor

Explanation: No change in the sensor output

signal.

Expected Engine

Response: “Open loop” operation only, may

cause a drop in system performance

and fuel efficiency.

Possible Causes:

1. Engine Wiring Harness Related

a. Pin circuit 11 wiring or connectors.

Pin 11 for “24 Pin” (MSE 1.0) Plastic-Cased

ECU.

Pin 20 for “32 Pin” (MSE 1.1) Plastic-Cased

ECU.

2. Oxygen Sensor Related

a. Sensor connector or wiring problem.

b. Sensor contaminated or damaged.

c. Sensor below the minimum operating

temperature (375°C, 709°F).

d. Poor ground path from sensor to engine

(sensor grounds through shell, see Oxygen

Sensor section).

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