Question about Chevrolet K2500
Im trying to find wiring diagram for my 99 suburban. I need to verifiy a few pins on the ECM are recieving power. I recently replaced the fuel pump but still not getting power from ecm to tell it to kick on. I have jumper across the relay and pump kicks on just fine with around 60 psi of pressure as soon as i remover the jumper wire pump kicks off. I order new a new ECM and having it programmed today at the dealership put i think its more of a wiring related issue and I would like to do further testing to verify before the dealership cost me my next born child.
if you have diagnostic equipment you will be able to see the signal through serial data(if you believe it)the cranksensor is located near the rear of the engine pointing towards the radiator i think it goes to a grey plug....
Posted on Jan 05, 2009
I checked all of the fuseable links and they were all good. Next I decided to check all the power wires to the ECM and also the grounds from a wiring diagram because the Mil is controlled by the ecm and the bulb was good. The ecm is located behind the glove box. Bingo, the orange wire was only reading 3-5 volts at the ECM, but 12.5 volts after the fuseable link at the underhood fuse block (passenger side firewall). I ran a temp wire directly from after the fuseable link to the orange wire at the ecm and the ecm turned back on and the Mil or "check engine soon" light came on too. The truck started up and has never run smoother.
Note that at first the truck just stalled out and I could restart it right away with no error codes. Eventually the stalling became more frequent with longer reset times required. Once it threw a "code 54" and I thought it was fuel related as each time the gas stopped and I could still start the truck with gas poured into the TB. Ignition ok. My fuel pump turned on and ran if I tested it. I even checked the pressure regulator and the fuel filter to no avail.The orange wire that powers up the ecm is technically part or the fuel pump relay circuit as it also feeds the fuel pump relay 12.5 volts all the time. The thin orange wire from the fuse block is joined to two other thin orange wires in the large group of wires that heads to the ecm along the firewall behind the engine. I had to dig it out of the many wires to find it and remove a lot of tape. It is amazing to me that this one little orange wire could cause so much grief and be so hard to track down. I could not have afforded to take this problem to the Dealer.
Posted on Mar 26, 2009
The GRAY wire i believe going to the fuel pump is the hot wire it should come on for 2 seconds with just the key in the on position this is were you should check voltage for 2 seconds then it will go away until you crank the truck.Your oil sending unit is behind your distributor that could be the cause .
Posted on Aug 01, 2009
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