P0625

P0625-GENERATOR FIELD CONTROL CIRCUIT LOW

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

Theory of Operation

There are two communication lines between the Powertrain Control Module (PCM) and Generator. Based on sensed battery voltage, the PCM commands the Generator to charge the batteries to a desired voltage. The max voltage the PCM will command the alternator to charge is 14.75 Volts. The PCM then receives feedback from the Generator on the voltage level it is charging the batteries through a sense line. The PCM will not light a MIL lamp for this fault.

- When Monitored:
When the ignition is on.

- Set Condition:
The PCM detects that the (K20) Generator Field Control circuit is shorted to ground.





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

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, erase DTCs.
3. Turn the ignition off for 75 seconds.
4. Start the engine and let idle for up to five minutes.
5. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. CHECK THE (K20) GENERATOR FIELD CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the Generator field harness connector.
3. Disconnect the PCM C1 harness connector.
4. Measure the resistance between ground and the (K20) Generator Field Control circuit at the Generator harness connector.

Is the resistance below 10k Ohms.

No

- Go To

Yes

- Repair the (K20) Generator Field Control circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE GENERATOR
1. Reconnect the PCM C1 harness connector.
2. Connect a jumper between the Generator output stud and the (K20) Generator Field Control circuit at the Generator field harness connector.
3. Turn the ignition on.
4. With the scan tool, read DTCs.

Did DTC P0625 become stored and P0626 become active or pending?

Yes

- Replace the Generator.
- Perform he POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.