P0628

DTC P0628 - FUEL PUMP RELAY CONTROL CIRCUIT LOW VOLTAGE

CIRCUIT DESCRIPTION
The engine control module (ECM) provides ignition voltage to the coil side of the fuel pump relay whenever the engine is cranking or running. The control module enables the fuel pump relay as long as the engine is cranking or running, and ignition system reference pulses are received. If no ignition system reference pulses are received, the control module turns OFF the fuel pump.

he fuel pump relay control circuit is equipped with a feedback circuit that is pulled up to 2.5 volts within the ECM. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is less than a predetermined voltage when commanded ON, this DTC sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC.
DTC P0628 Fuel Pump Relay Control Circuit Low Voltage

CONDITIONS FOR RUNNING THE DTC
- The fuel pump relay is commanded ON.
- The ignition 1 voltage is more than 10.5 volts.
- DTC P0628 runs continuously once the above conditions are met.

CONDITIONS FOR SETTING THE DTC
- The ECM detects that the fuel pump relay control circuit is shorted to ground.
- The condition exists for less than 1 second.

ACTION TAKEN WHEN THE DTC SETS
- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL) will not illuminate.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
- The driver information center, if equipped, may display a message.

CONDITIONS FOR CLEARING THE DTC
- A current DTC Last Test Failed clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- Clear the DTC with a scan tool.

DIAGNOSTIC AIDS
- Use the J 35616-B Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
- The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Computers and Control Systems Component Views.
- If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The output driver module (ODM) information is in the ODM data list.
- For an intermittent condition, refer to Intermittent Conditions. Diagnostic Strategies

TEST DESCRIPTION

Steps 1-2:

Steps 3-5:

Steps 6-9:

The number below refers to the step number on the diagnostic table.
4. This step verifies that the control module is providing voltage to the fuel pump relay.