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FAULT CODE 255

Fuel Shutoff, Fan Clutch, Engine Brake Supply Circuit

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Overview

CODE REASON EFFECT
Fault Code: 255
PID: S026
SPN: 701
FMI: 3
LAMP: Yellow
SRT: 00-603		 Externally supplied voltage detected at one of these driver pins: fuel shutoff valve pin 16, fan clutch pin 7, or engine brake pin 18 of the actuator harness connector. Fuel shutoff valve will not close or fan will run all the time or engine brake will activate.

Fuel Shutoff Circuit

Circuit Description

If voltage is supplied externally on these supply wires, the fuel shutoff valve, fan clutch, or engine brake enable voltage will stay on.

Component Location

Refer to the vehicle wiring diagram for the location of the engine brakes. Location will vary with vehicle make and model. Refer to the vehicle manufacturer’s publications for more information on troubleshooting and repair of the fan clutch. The fuel shutoff solenoid valve is mounted on top of the fuel supply pump on the engine. The solenoid is controlled by the ECM.

Shop Talk

If there is an external shutdown system on the vehicle, make sure it is not miswired and feeding voltage into the fuel shutoff supply circuit.

Cautions and Warnings

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the actuator harness.
STEP 1A. Inspect the harness and the ECM connector pins. No damaged pins
STEP 1B. Check for the external voltage source. Less than 1.5 VDC
STEP 1C. Check for a short circuit from pin to pin. More than 100k ohms
STEP 1D. Check for a short circuit from pin to pin. More than 100k ohms
STEP 1E. Check for a short circuit from pin to pin. More than 100k ohms
STEP 2. Clear the fault codes.
STEP 2A. Disable the fault code. Fault Code 255 inactive
STEP 2B. Clear the fault codes. All fault codes cleared

Guided Step 1 – Check the actuator harness.

 CAUTION 

 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
Guided Step 1A – Check the harness and the ECM connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the actuator harness connector from the ECM.
  • Flush and clean the connector pins using electronic contact cleaner, Part Number 3824510.

Action

  • Bent or broken pins
  • Pushed back or expanded pins
  • Corroded pins
  • Moisture in or on the connector
  • Missing or damaged seals
  • Dirt or debris in or on the connector pins.
OK NOT OK
No damaged pins Repair the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Repair the actuator harness. Refer to Procedure 019-203.
  • Replace the actuator harness. Refer to Procedure 019-043.
  • Replace the ECM. Refer to Procedure 019-031.
  • Replace the o-ring on the 28-pin connector if it is damaged or missing. Refer to Procedure 019-203.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
Guided Step 1B – Check for the external voltage source.

Conditions

  • Disconnect the actuator harness connector from the ECM.
  • Turn keyswitch ON.

Action

  • Measure voltage from pins 7, 16, and 18 in actuator harness connector to engine block ground.

Note: Internal ECM damage can result from external power sources connected to these actuator pins.
OK NOT OK
Less than 1.5 VDC Remove the external voltage source.

  • There is an external source connected to the wire at which more than 1.5 VDC was measured. Find the voltage source, and remove it from the circuit.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
Guided Step 1C – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the actuator harness connector from the ECM.
  • Disconnect the actuator harness from the fuel shutoff solenoid.

Action

  • Measure resistance from pin 16 to all other pins in actuator harness connector, except pins 9, 25, and 27.
OK NOT OK
More than 100k ohms Repair or replace the actuator harness.

  • Repair the actuator harness. Refer to Procedure 019-203.
  • Replace the actuator harness. Refer to Procedure 019-043.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
Guided Step 1D – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the actuator harness connector from the ECM.
  • Disconnect the 9-pin OEM harness connector from the OEM harness.
  • Disconnect the sensor harness connector from the ECM.

Action

  • Measure resistance from pin 7 to all other pins in the actuator harness connector, except 9, 25, and 27.
  • Measure resistance from pin 7 in the actuator harness connector to all pins in the sensor harness connector.

Note: It is necessary to do pin-to-pin checks on the OEM side of the 9-pin connector. See the OEM manual for specific connectors/wires that are in common with the fan clutch wiring.
OK NOT OK
More than 100k ohms Repair or replace the actuator harness.

  • Repair the actuator harness. Refer to Procedure 019-203.
  • Replace the actuator harness. Refer to Procedure 019-043.

 CAUTION 

 

To reduce the possibility of pin and harness damage, use this test lead when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead.
Guided Step 1E – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the actuator harness connector from the ECM.

Action

  • Measure resistance from pin 18 to all other pins in the actuator harness connector, except pins 9, 25, and 27.
OK NOT OK
More than 100k ohms Repair or replace the actuator harness.

  • Repair the actuator harness. Refer to Procedure 019-203.
  • Replace the actuator harness. Refer to Procedure 019-043.

Guided Step 2 – Clear the fault codes.

Guided Step 2A – Disable the fault code.

Conditions

  • Connect all components.

Action

  • Start the engine and let it idle for 1 minute.
  • Verify Fault Code 255 is inactive.
OK NOT OK
Fault Code 255 inactive Return to the troubleshooting steps or contact your nearest Cummins Authorized Repair Location if all the steps have been completed and checked again.

Guided Step 2B – Clear the fault codes.

Conditions

  • Connect all the components.

Action

  • Erase the inactive fault codes using INSITE™.
OK NOT OK
All fault codes cleared Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting chart
Last Modified:  29-Oct-2003
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Published by Jack

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