P2509

P2509-PCM/PCM POWER INPUT SIGNAL INTERMITTENT

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Powertrain Control Module (PCM) receives a constant voltage from the batteries through the battery wires that are connected directly to the positive (+) battery post. The PCM receives switched battery input through the vehicle Ignition Switch wire when the vehicle is turned on. The PCM will illuminate the ETC lamp immediately after the diagnostic runs and fails. During the time the customer may experience some performance effects such as engine dying or hard starting. Fault information, trip information could be inaccurate.

- When Monitored:
Continuous - key on or key off.

- Set Condition:
Battery voltage was removed from the Powertrain Control Module (PCM) while it was powered on. This could be during engine operation, or after key off while the PCM was powering down. This powering down condition can last up to 10 minutes.





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

1.

NOTE: It can take up to 10 minutes for the PCM to power down after the ignition is turned off. Disconnecting the batteries during this time will cause this DTC to set.
CHECK FOR POOR CONNECTIONS AT THE BATTERIES
1. Visually inspect the wiring at the battery for damaged wires, or corrosion.

Are the connections tight and free of corrosion?

Yes

- Go To 2

No

- Repair the poor connections at the batteries.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

2. CHECK FOR LOW BATTERY VOLTAGE / DEFECTIVE BATTERY
1. Disconnect both batteries.

NOTE: Keep the batteries disconnected through the entire test procedure.

2. Check the battery(s) for correct operation. Battery System.

Do both batteries pass the battery test?

Yes

- Go To 3

No

- Recharge or replace the battery(s).
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE PCM FUSED B+ CIRCUITS
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance between the positive battery post and the two PCM Fused B+ circuits.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the open Fused B+ circuit to PCM.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. CHECK THE PCM GROUND CIRCUITS
1. Measure the resistance between the negative battery post and the two PCM ground circuits.

Is the resistance less than 5.0 Ohms?

Yes

- Go To 5

No

- Repair the open ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. BATTERY POSITIVE SHORTED TO OTHER CIRCUITS
1. Measure the resistance between the two PCM Fused B+ circuits and all other circuits in the PCM harness connector, except other supply circuits.

Is the resistance above 10k Ohms?

Yes

- Go To 6

No

- Repair the battery circuit short to other circuits in engine harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. RETURN CIRCUIT SHORTED
1. Measure the resistance between the two PCM ground circuits and all other circuits in the PCM harness connector, except other ground circuits.

Is the resistance above 10k Ohms?

Yes

- Go To 7

No

- Repair or replace the engine harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

7. BATTERY POSITIVE SHORTED TO GROUND
1. Measure the resistance between the PCM Fused B+ circuits and ground.

Is the resistance above 10k Ohms?

Yes

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

No

- Repair Battery Fused B+ circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.