9000 Aero L4-2290cc 2.3L DOHC Turbo EFI (1996)
Fuel Pump Relay: Description and Operation
The fuel pump relay is located in the relay holder on the passenger's side. This relay supplies the fuel pump and oxygen sensor heating elements with
current.
The fuel pump relay. is controlled via the anti-theft alarm's control module from pin 56 of the Trionic engine control module. Grounding pin 56 causes
the relay to operate.
If the ignition has been switched off for longer than 15 minutes, the fuel pump relay will operate for 2 seconds when the ignition switch is turned to the
ON position. The purpose of this is to build up the fuel pressure prior to pre-injection, which takes place when the crankshaft starts to rotate.
The fuel pump relay then operates as soon as the ECM receives pulses from the crankshaft position sensor.
