Fuel Pump Relay: Description and Operation

Fuel Pump Relay








The fuel pump relay is located in the relay holder under the dashboard by the steering wheel. The relay supplies the fuel pump and the oxygen sensor pre-heating.

The fuel pump relay is controlled from pin 50, which is grounded to operate the relay.

When the ignition is turned to the "ON" position, the fuel pump relay will operate for 1 second. This is to build up pressure prior to pre-injection, which is performed when the crankshaft starts to rotate.

Diagram:

Diagnosis
^ Diagnostic trouble code P1645 will be generated in the event of a break or short-circuit to ground.
^ Diagnotic trouble code P1655 will be generated in the event of a short-circuit to B+.
^ If there is no current from relay pin 87 when the relay is active, diagnostic trouble code P1641 will be generated.

NOTE: The pump runs for 1 second when the ignition is switched on.