P0629

Wiring Diagram:

Fuel Pump Relay Control Circuit Voltage High:

P0629- FUEL PUMP RELAY CONTROL CIRCUIT HIGH VOLTAGE
The fuel pump relay is located in the underhood fuse block (UHFB). The ECM controls the fuel pump motor by supplying a ground to the fuel pump relay coil whenever the engine is cranking or running. When the fuel pump relay is commanded Off (circuit not grounded), the voltage level at the ECM should be high (ignition voltage). When the fuel pump relay is commanded On (circuit grounded), the voltage level at the ECM should be low. The ECM fuel pump relay feedback circuit uses a pull-up voltage (2.6-4.6 volts), which allows the ECM to individually differentiate between an open, short to ground or short to voltage. DTC P0629 will set if the ECM detects higher than normal feedback voltage when fuel pump relay is commanded On with engine cranking/running.

DTC PARAMETERS
DTC P0629 will set if fuel pump relay feedback voltage is greater than 4.6 volts when fuel pump relay is commanded On when;
^ Condition exists for longer than 0.5 seconds
^ Engine speed is greater than 40 rpm
^ Battery voltage is between 7.5 and 15.0 volts

DTC P0629 diagnostic runs continuously once the above conditions have been met.

P0629 is a type D DTC

DIAGNOSTIC AIDS

IMPORTANT: The ECM will only energize the fuel pump relay when the engine is cranking or running. If the ignition is turned On and the engine is not cranking, the fuel pump will NOT run.

To locate an intermittent problem, use Scan tool to command the FUEL PUMP RELAY On and Off while wiggling circuit 497.

Fuel pump relay coil resistance: 70-115 ohms.