Truck wont start and scan tool wont connect to PCM

Discussion in 'Forum Requests' started by Kiwisrt10, May 22, 2021.

  1. Kiwisrt10

    Kiwisrt10 New Member

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    Hi guys
    So for about a month my truck started playing up, not starting sometime, trans holding gears and coughing and spluttering like its starving of fuel. then all of a sudden wouldnt start at all. when i turn it to ignition and press start it cranks but no ignition. ive spent weeks looking at it and spent lots on auto sparkys to no success. What i have figured out is on the trans relay if i physically push the relay from 87a to 87 it powers up the starting sequence and the truck will start. Then i can scan it and no codes present.
    Im guessing there is a broken wire somewhere so when i physically push the relay over it powers up the circut but backwards. Can anyone confirm when you turn the key to ignition the trans relay flicks the constant power from 30 to 87? and any ideas from there?
     
  2. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Remove the fuse box and look carefully for issues underneath it.

    (Disconnect battery)
     
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  3. Kiwisrt10

    Kiwisrt10 New Member

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    Can you confirm On the Trans relay which of the 5 pins have power and earth at key off position and ignition on position??
     
  4. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Sorry, I can't help you there.

    I basically learned this about electrical circuits...

    Don't pee on an electric fence.

    In the rain...
     
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  5. Kiwisrt10

    Kiwisrt10 New Member

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    No worries Ronnie. Someone else who reads it might be able to check. It sucks cause Torrie just sent me a new tune from Unleashed turning and I can't try it out yet
     
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  6. AMS3

    AMS3 Well-Known Member

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    Hope you get it squared away soon. As for the Tune, which tuner did you buy from him? I'm looking at the HP Tuners RTD. Did it come with generic tunes, or did you ask for something other than a "canned" tune that he offers? Funny side note, he lives about three hours away from me in Florida. I'm actually thinking of taking a drive to his shop, see if he'll install it there.
     
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  7. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    A canned tune from an experienced Tuner on a stock engine will get you close. If you are jumping on a dyno, you will need to weld a couple of bungs into the exhaust, prior, so you will be able to accurately read the A/F ratio during the pulls.
     
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  8. Kiwisrt10

    Kiwisrt10 New Member

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    I finally solved it today guys. If anyone wants to know anything electrically about there's utes I pretty much know it now. Approx 80hrs of reading thru electrical schematics
     
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  9. AMS3

    AMS3 Well-Known Member

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    Good to hear. I'm a dummy when it comes to electrical.
     
  10. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Was it a bad ground??
     
  11. Kiwisrt10

    Kiwisrt10 New Member

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    Rear plug on the pcm is right under the join of the hood. Lots of water damage behind the plug. I removed the computer and found the #22 pin (pcm constant power)completely corroded off and snapped in the plug. I pulled the pcm apart and re soldered in a new pin on the mother board and she fired up.
     
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  12. rottenronnie

    rottenronnie Well-Known Member Supporting Member

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    Speaking of water...

    When you lift the hood on my truck after a wash or in the rain- (should be the same on all SRT-10s with OEM hoods), water pees all over the Throttle Position Sensor.

    That created some weird and wonderful things such as high-idle, BIG loss of WOT power.
    I put silicone sealant all over mine (helped) but as we all know water and power don't play well together.
     
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