P0626

P0626-GENERATOR FIELD CONTROL CIRCUIT HIGH

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 Generator to charge is 14.75 Volts. The PCM then receives feedback from the alternator 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 engine is running.

- Set Condition:
The PCM detects that the Generator Field Control circuit is open or shorted to voltage. Two trip fault.





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

Diagnostic Test

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, clear read DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECK THE (K125) GENERATOR FIELD CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (K125) Generator Field Control circuit at the Generator harness connector.

Is there any voltage present?

Yes

- Go To 3

No

- Go To 4

3. CHECK THE GENERATOR FOR A SHORT TO VOLTAGE
1. Disconnect the Generator field harness connector.
2. Turn the ignition on.
3. Measure the voltage on the (K125) Generator Field Control circuit at the Generator harness connector.

Is there any voltage present?

Yes

- Repair the (K125) Generator Field Control circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

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

4. CHECK THE (K125) GENERATOR FIELD CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Disconnect the Generator field harness connector.
2. Measure the resistance of the (K125) Generator Field Control circuit between the Generator harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the Generator Field Control circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the relay and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Verify that there is good pin to terminal contact at the relay and PCM harness connectors.
5. Perform any Technical Service Bulletins (TSBs) that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM). .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.