Question about 2003 GMC Sierra
Truck was idling and run out of gas, put gas in a few days later, tried to start, starter wouldn't engage, although it will turn over with the relay pulled and the pins jumped, won't start tho, checked all fuses everywhere twice, switched relays ,won't start in neutral ,security cassock light comes on when key is turned on, and stays on, tried 3 time 30 min relearn light stays on solid and don' turn off after 10-15 min??
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Posted on Jan 02, 2017
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
sounds like starter solenoid,try cycling the ignition on start on start repeatly but do not go back to the off position off on start will activate the fuel pump repeatly and might flood it,with a faulty solenoid you can usually cycle the ignition repeatly and it will finally engage the starter
Posted on Mar 29, 2009
I have seen many ign switchs. Check to see if the theft doesn't flash when you try to start. It is still posable that the starter is going. Have someone crank the engine. Check for power on the purple wire. If there is power and the it does not crank. Check that the big wire has a soild 12 volts. You can use a screw driver and jump the purple and the big 12v battery at the starter and it should turn on if not replace the starter
Posted on Dec 02, 2009
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