P0627

P0627-FUEL PUMP RELAY CIRCUIT






For a complete wiring diagram refer to: Electrical Diagrams

When Monitored
With the ignition on. Battery voltage greater than 10.4 volts.

Set Condition
An open or shorted condition is detected in the fuel pump relay control circuit. One Trip Fault. Three good trips to turn off the MIL.

Possible Causes
- (F20) FUSED IGNITION SWITCH OUTPUT CIRCUIT
- (A109) FUSED B+ CIRCUIT
- (K31) FUEL PUMP RELAY CONTROL CIRCUIT
- (K31) FUEL PUMP RELAY CONTROL CIRCUIT SHORTED TO GROUND
- FUEL PUMP RELAY
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test
1. FUEL PUMP RELAY OPERATION





Ignition on, engine not running.
With a scan tool, actuate the Fuel Pump Relay

Is the Fuel Pump Relay operating?
Yes >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 2
2. FUEL PUMP RELAY
Turn the ignition off.
Remove the Fuel Pump Relay from the IPM.
Measure the resistance of the Fuel Pump Relay Coil.

Is the resistance between 70 to 90 ohms?
Yes >> Go To 3
No >> Replace the Fuel Pump Relay.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. (F20) FUSED IGNITION SWITCH OUTPUT CIRCUIT





Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (F20) Fused Ignition Switch Output circuit.

Does the test light illuminate brightly?
Yes >> Go To 5
No >> Repair the open or short to ground in the (F20) Fused Ignition Switch Output circuit. Inspect the related fuse and repair as necessary.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. (A109) FUSED B+ CIRCUIT





Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (A109) Fused B+ circuit.

Does the test light illuminate brightly?
Yes >> Go To 5
No >> Repair the open or short to ground in the (A109) Fused B+ circuit. Inspect the related fuse and repair as necessary
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (K31) CONTROL CIRCUIT OPEN





Turn the ignition off.
Disconnect the PCM harness connectors.

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 Relay Control circuit from the IPM to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?
Yes >> Go To 6
No >> Repair the open in the (K31) Fuel Pump Relay Control circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (K31) CONTROL CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (K31) Fuel Pump Relay Control circuit in the IPM.

Is the resistance below 100 ohms?
Yes >> Repair the short to ground in the (K31) Fuel Pump Relay Control circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 7
7. PCM

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

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?
Yes >> Repair as necessary
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test