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Co Worker has an 09 G8 and the fuel pump stopped working. He thought the pump went out but theres no power at the harness. Mini fuse in trunk has power and he said theres power at the relay. Still no power at the harness, even with nwe relay. Is there a Driver module on these cars? is the relay activated through a ground signal from the PCM? Also is there a crash shut off switch, and where? Thanks for any help/info. He parked it in teh drive at night, went to leave for work and no pump.
The fuel pump relay is controlled by the PCM. Basically the relay is wired like this: Pin 85 is 12 volt power controlled by the PCM, pin 86 is ground, pin 87 is constant 12 volt power from the 20 amp fuse, and pin 30 goes to the fuel pump. There is no driver module or rollover switch. You say he checked for power at the relay and found it, likely on pin 87 which is the constant power supplied through the fuse. You need to also check power on pin 85; it should power up briefly when the key is first turned on (to prime the pump) and should come back on while cranking.
The fuel pump will only be on when the PCM commands it to be on, so if he's looking for power at the pump with just the key on, there won't be power unless the engine is being cranked over.
I have seen keys go bad and cause a no-fuel issue. Depending on how the immobilizer is setup from the factory. Try a different ignition key.
If that doesnt fix it, go with the post above