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P254C






P254C-PTO SPEED SELECTOR SENSOR CIRCUIT LOW

For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The remote accelerator pedal position sensor varies the signal voltage to the ECM as the remote accelerator pedal is depressed and released. Low signal voltage is received by the ECM when the remote accelerator lever is a 0%. A high signal voltage is received by the ECM when the remote accelerator is at 100%. The remote accelerator pedal position circuit contains a remote accelerator pedal position 5-volt supply, remote accelerator pedal position return and remote accelerator pedal signal. When the ECM senses a signal voltage lower than the normal operating range of the sensor, this fault is set. NOTE. The remote accelerator pedal or lever location varies with each original equipment manufacturer (OEM). Refer to the OEM troubleshooting and repair manual. The ECM will light the MIL lamp immediately after this diagnostic runs and fails. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
Key on.

- Set Condition:
The ECM detects that the remote accelerator pedal signal voltage is less than 0.1 volts for more than 1 second.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure

1. OTHER DTC'S
1. Ignition on, engine not running.
2. With the scan tool, read DTC's.

Are there any sensor supply fault codes?

Yes

- Repair other DTC's first.

No

- Go To 2

2. P254C ACTIVE

Is P254C active?

Yes

- Go To 3

No

- Refer to the INTERMITTENT CONDITION - DIESEL diagnostic procedure. Intermittent Condition Test

3. OPEN CIRCUIT
1. Turn the ignition off.
2. Disconnect the remote accelerator pedal or lever position sensor from the harness.

NOTE: Check connectors - Clean/repair as necessary.

3. Ignition on, engine not running.
4. Measure the voltage from the accelerator pedal or lever position (K854) 5-volt supply circuit to the accelerator pedal or lever position (K400) return circuit at the sensor harness connector.

Is the measured voltage between 4.75 and 5.25 volts?

Yes

- Go To 4

No

- Go To 6

4. P254D ACTIVE
1. While monitoring the scan tool jumper between the accelerator pedal or lever position (K854) 5-volt supply circuit and the accelerator pedal or lever position (K128) signal circuit at the sensor harness connector.

Is DTC P254D active and DTC P254C inactive?

Yes

- Go To 5

No

- Go To 6

5. P254C ACTIVE
1. Turn the ignition off.
2. Reconnect the remote accelerator pedal or lever position sensor from the harness.
3. Ignition on, engine not running.
4. With the scan tool, read DTC's.

Is DTC P254C active?

Yes

- Replace the remote accelerator pedal or lever.
- Perform ECM VERIFICATION TEST. Powertrain Verification Test

No

- Repair complete. The removal and installation of the connector corrected the failure.

6. (K854) 5-VOLT SUPPLY CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the remote accelerator pedal or lever position sensor from the harness.
3. Disconnect the C2 ECM harness connector.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the resistance between the C2 ECM harness connector (K854) 5-volt supply circuit and the remote accelerator pedal or lever harness connector (K854) 5-volt supply circuit.

Is the resistance less than 10 ohms?

Yes

- Go To 7

No

- Repair the open (K854) 5-volt supply circuit.
- Perform ECM VERIFICATION TEST. Powertrain Verification Test

7. (K128) SIGNAL CIRCUIT OPEN
1. Measure the resistance between the C2 ECM harness connector (K128) signal circuit and the remote accelerator pedal or lever harness connector (K128) signal circuit.

Is the measured resistance less than 10 ohms?

Yes

- Go To 8

No

- Repair the open (K128) signal circuit.
- Perform ECM VERIFICATION TEST. Powertrain Verification Test

8. (K128) SIGNAL CIRCUIT SHORT TO OTHER CIRCUIT
1. Measure the resistance between the (K128) signal circuit in the C2 ECM harness connector and all other circuits in the C2 ECM harness connector.

Is the measured resistance greater than 100k ohms?

Yes

- Go To 9

No

- Repair the (K128) signal circuit shorted to another circuit.
- Perform ECM VERIFICATION TEST. Powertrain Verification Test

9. (K128) SIGNAL CIRCUIT SHORT TO GROUND
1. Measure the resistance between the (K128) signal circuit in the C2 ECM harness connector and ground.

Is the measured resistance greater than 100k ohms?

Yes

- Go To 10

No

- Repair the (K128) signal circuit shorted to ground.
- Perform ECM VERIFICATION TEST. Powertrain Verification Test

10. ECM
1. Reconnect the C2 ECM harness connector.
2. Reconnect the remote accelerator pedal or lever position sensor from the harness.
3. Ignition on, engine not running.
4. With the scan tool, read DTC's.

Is DTC 254C stored?

Yes

- Repair complete. The removal and installation of the connector corrected the failure.

No

- Replace and program the Engine Control Module.
- Perform ECM VERIFICATION TEST. Powertrain Verification Test

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