NGC

P0627-FUEL PUMP CONTROL CIRCUIT

For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the engine running and battery voltage greater than 10.4 volts.

- Set Condition:
The PCM detects that the actual state of the fuel pump control does not match the intended state.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. ACTIVE DTC
Ignition on, engine not running.
With the scan tool, select View DTCs.
Is the DTC Active at this time?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking For An Intermittent DTC

2. FUEL PUMP CONTROL OPERATION FROM THE PCM




Stop the Fuel Pump actuation.
Turn the ignition off.
Disconnect the C1 TIPM harness connector.

NOTE: Before continuing, check the TIPM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Ignition on, engine not running.
Using a 12-volt test light connected to B+ probe the (K31 Fuel Pump Control circuit in the C1 TIPM harness connector.
Using a scan tool actuate the Fuel Pump under the PCM actuations.

NOTE: The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery.

Does the test light illuminate accordingly during the actuation?

Yes

- Go to 5

No

- Go to 3

3. (K31) FUEL PUMP CONTROL CIRCUIT OPEN




Turn the ignition off.
Disconnect the C3 PCM harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K31) Fuel Pump Control circuit from the C1 TIPM harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?

Yes

- Go to 4

No

- Repair the open in the (K31) Fuel Pump Control circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

4. (K31) FUEL PUMP CONTROL CIRCUIT SHORTED TO GROUND




Measure the resistance between ground and the (K31) Fuel Pump Control circuit in the TIPM C1 harness connector.
Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (K31) Fuel Pump Control circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 8

5. (N1) FUEL PUMP OUTPUT CIRCUIT OPEN




Turn the ignition off.
Disconnect the C5 TIPM harness connector.
Disconnect the Fuel Pump Module harness connector.
Measure the resistance of the (N1) Fused Fuel Pump Output circuit from the C5 TIPM harness connector and the Fuel Pump Module harness connector.
Is the resistance above 5.0 ohms?

Yes

- Repair the open in the (N1) Fused Fuel Pump Output circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 6

6. (N1) FUEL PUMP OUTPUT CIRCUIT SHORTED TO GROUND




Measure the resistance between ground and the (N1) Fused Fuel Pump Output circuit at the Fuel Pump Module harness connector.
Is the resistance below 100 ohms?

Yes

- Repair the short to ground in the (N1) Fused Fuel Pump Output circuit.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 7

7. FUEL PUMP MODULE/TIPM




Connect the C3 PCM harness connector.
Connect the C1 and C5 TIPM harness connectors.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the (N1) Fused Fuel Pump Output circuit at the Fuel Pump Module harness connector.
Using a scan tool actuate the Fuel Pump Module.
Does the test light illuminate?

Yes

- Replace the Fuel Pump Module.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Replace the Totally Integrated Power Module.
- Perform the PCM Verification Test. Powertrain Verification Test

8. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Fuel Pump Module and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Fuel Pump and Control Module connectors.
Search for any Technical Service Bulletins that may apply.
Were there any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Replace and program the Powertrain Control Module.
- Perform the PCM Verification Test. Powertrain Verification Test