P0629

DTC P0629

CIRCUIT DESCRIPTION
The powertrain control module (PCM) 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 crankshaft reference pulses are received. It no crankshaft reference pulses are received, the control module turns OFF the fuel pump.

The fuel pump relay control circuit is pulled up to 2.5 volts within the PCM using a bypass resistor that is connected internally to ignition voltage. This resistor allows the PCM to detect a high voltage condition if the fuel pump control circuit is open when the pump relay is not commanded ON. The control module monitors the voltage on the fuel pump relay control circuit. If the PCM detects a high voltage condition on the fuel pump relay control circuit, DTC P0629 sets.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTC:
P0629 Fuel Pump Relay Control Circuit High Voltage

CONDITIONS FOR RUNNING THE DTC
- The engine speed is more than 0 RPM.
- The ignition is ON, with the engine OFF.
- The engine controls ignition relay voltage is more than 10.5 volts.
- The above conditions are met for more than 1.0 second.

OR

- The engine speed is more than 80 RPM.
- The engine controls ignition relay voltage is more than 10.5 volts.
- The above conditions are met for more than 1.0 second.
- DTC P0629 runs continuously once the above conditions have been met.

CONDITIONS FOR SETTING THE DTC
- The PCM detects the voltage on the fuel pump relay control circuit is more than 2.79 volts with the ignition ON and the engine OFF.
- The condition exists for less than 1 second.

OR

- The PCM detects the voltage on the fuel pump relay control circuit is more than 2.79 volts when the following occurs:
- The engine is cranking or running.
- The PCM commands the fuel pump relay OFF. The PCM turns OFF the fuel pump relay control circuit for 8 ms and monitors the fuel pump relay control circuit for voltage. The PCM performs this test up to 5 times an ignition cycle.
- The condition exists for less than 0.5 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- 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 emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- The circuit status parameter changes from OK to Fault if there is a condition with the circuit or a connection.
- For an intermittent condition, refer to Intermittent Conditions. Diagnostic Strategies

TEST DESCRIPTION

Steps 1-11:

Steps 12-13:

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.
5. This step tests for an open in the ground circuit to the fuel pump relay.