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I have a 2008 Tahoe with a 5.3 flex fuel LMG vin 0. I recently had the motor blow and replaced it with what I thought was the identical motor out of a 2008 Silverado. I confirmed this engine is a 2008 5.3 flex fuel LMG out of a 2008 1500 Silverado. the issue is I can not figure out why the New engines harness has one extra wire on it. The new engine has an extra dark Grn/Wht wire in the X2 connector in position P4 see image.
Can anyone please tell me what this is for and what do I do with it. see my original X2 here:
Some trucks and suv's use a Fuel Pump Control Module (FPCM). Some do not. The module has the ability to pulse width modulate the fuel pump and run it at different speeds and pressures. The FPCM communicates with the ECM info about fuel pressure so it can constantly adjust pulse with.
On vehicles with the FPCM the ECM's fuel pump relay control goes to the FPCM. The FPCM then controls the pump based on that request from the ECM. On vehicles that DO NOT have a FPCM, the fuel pump relay control goes to the fuse block, and controls a relay directly.
I wish I had seen your reply earlier! what I ended up doing was removing the green\white wire from the fuse block connector (Pin 50 on ECM) and running a jumper wire to the missing pin in the small connector (X300) by the FPCM and that resolved the problem. I harvested the green\white wire and pin from my old harness and used it on the new one. see image. I hope this helps out anyone that has come across this. Thank You!
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