Tuesday, May 31, 2011

2000 CHEV 1500 5.3 fuel pump wiring diagram?

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you said the ECM B fuse is good , now check for power at the Grey wire ( at the fuel pump connector) you need someone to turn the ignition switch on while you check for power, the ECM will only power the pump for TWO seconds.. then shuts off power to the pump unless it sees ignition reference pulses. If your test light turns on for 2 second then goes out, change the pump . If the pump is already replaced, then also re confirm that pump is new and not after market pump.In some cases after market fuel pump are the cause of problem.So get OEM fuel pump.
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Ok , let's see if the relay is being triggered.
place your finger on top of the relay and have someone turn the ignition on, you should feel the relay click. if it does, the the problem lies between the relay and the fuel pump connector (open wire). if it doesn't click and the ECM b fuse is good, then one of two things.
#1 check the ground wire to the engine block behind the power steering pump.( that's the relay ground)
#2 check signal voltage from the computer( ecu/pcm) to the relay,
by probing the prong where the relay goes in , one of them should have power for two seconds when the ignition is turned on. If no power then faulty ( ecu/pcm).
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Also check for 12v at the PCM.If no 12 volt PCM is the issue.The pcm and ecu are name of one and the same module.
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There's a ground strap that attaches to the frame and a ground wire that goes to the filler neck.
Also it can be blown VCM/PCM 20 Amp fuse. If I read the wiring diagram correct, the PCM actually supplies power to the fuel pump relay so since it was blown, no power to the relay or the pump.-------------
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Also you try temporarily bypass the ground to a different location and check.If the actual ground connection is rusted it can cause problems.