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Thread: Won't start after wired up

  1. #21
    Join Date
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    Like maybe the power lead that runs to the starter relay has been taken off or the fuse popped?
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  2. #22
    Join Date
    Sep 2007
    Location
    Texas
    Posts
    5,301
    what year computer did you get?

  3. #23
    Join Date
    May 2008
    Location
    Kentucky
    Posts
    144
    same pcm out of the 03
    1996 GMC extended cab, 2003 5.3/auto

  4. #24
    Join Date
    Oct 2003
    Posts
    473
    On my '96, I wired the large yellow coming out of the C-100 firewall connector, to the large white wire in the LS1 harness, that called for keyed 12 volt. BAM! It started.

  5. #25
    Join Date
    May 2008
    Location
    Kentucky
    Posts
    144
    Well I hooked the solenoid wire up to a big yellow wire in old harness. It would come on when in crank position. The truck would then crank with key, so believe that is figured out.
    Then when I pulled a plug to try and see if I had spark, all I get is the starter solenoid spinning. so it looks like I'll be getting a starter tomorrow.
    The plugs didn't look good either so will go ahead and replace those as well. Could be the culprit for it not starting.
    1996 GMC extended cab, 2003 5.3/auto

  6. #26
    Join Date
    Sep 2007
    Location
    Texas
    Posts
    5,301
    Yes replace that starter and slap in some new plugs.

  7. #27
    If fouled plugs dont fix it, I have the solution, just gimme a call...


    Last edited by LSXmyford; 08-09-2008 at 05:49 AM.
    LSX conversions, so easy a caveman can do it.

  8. #28
    Join Date
    May 2008
    Location
    Kentucky
    Posts
    144
    ok so now it will crank fine with ingition key. But not getting any spark. Is there kind of test I can do on the ignition coils? I've tested and am getting power and ground to the wires to each side of coil packs. The relay to nelson wiring is clicking at was told it should be. Everything now has a good power and ground but no spark.
    Any ideas to what to check would be great. Do these engines have any kind of module like the ones with distributors have? That would cause it not to have spark?
    1996 GMC extended cab, 2003 5.3/auto

  9. #29
    Join Date
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    It sure sounds like VATS holding you up. Do you have access to someone with HPTuner software that can download your file and see if the VATS is turned off?
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  10. #30
    Join Date
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    There are two other things can can be holding up your spark, one is the cam position sensor on the top of the shortblock at the back behind the intake manifold, the other would be the crankshaft position sensor on the passenger side of the block around the starter location. If either are bad, not connected or have bad or broken wires the engine will not fire. I pinched the cam position sensor wires between the block and transmission bellhousing once and the truck wouldn't start. I then had to repair the wires since they were smashed beyond recognition when tightening the bellhousing.
    Last edited by RedHeartbeat; 08-10-2008 at 11:08 AM.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

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