SES lights and only 1&2 gears...

Discussion in 'TBI & EFI Conversions' started by usar17, Aug 9, 2017.

  1. usar17

    usar17 Full Access Member

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    I can never get a few weeks before something makes me wanna curse with this truck lol.

    Was towing my boat, pulled it out of the water today and it didn't idle right. Started driving home and after pulling a hill noticed it didn't shift up. Messed with shifter some and noticed im running in 2nd only. Pulled over, shut it down. Couldnt turn her back over. Had to use jump box. (No previous battery issues and truck was at 13v before and after shutting it off). So im thinking something shorted out when im the water.

    Got home, checked Trans fluid, thats good. Plugged in laptop. TPS showimg 85% at idle, that aint good. Following malfunction codes stored: 02 Sensor Failure, MAP sensor high, IAC Failure, Fuel Pump Relay Failure.

    Letting it sit over night. Any suggestions where to start? Rear axle was submerged, maybe o2 sensor. Eng and trans shouldnt have been wet.

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  2. 1987 GMC Jimmy

    1987 GMC Jimmy Full Access Member

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    If there's even a remote chance of water having got in there, I'd pull all the plugs out and let it sit overnight. The next day I'd inspect the oil and then change it if need be. It does sound like you encountered an electrical problem, which any level of moisture can act as a catalyst to. You had failures all across the board. I'm guessing you meant the TPS was at .85V at idle? You're right, that's not good. Not even a poorly made sensor should be that high. If it were me, I'd let it sit in the sun for a day, disconnect the battery for thirty seconds and reconnect. See how it runs then. If you wouldn't have mentioned the boat launch and your concerns of something shorting out, my first potential diagnosis would have been a bad ECM. I had a short happen at a spark plug wire to the frame from rats chewing on the wires, and that did destroy the ECM and blew two fuses in my Caprice so the ECM thing is definitely worth not discounting in my opinion.
     
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  3. 1987 GMC Jimmy

    1987 GMC Jimmy Full Access Member

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    Oh, shit. You have a 4L60E with a later OBD I PCM in it, don't you? That inability to get out of second sounds like a wonky transmission circuit if you ask me. It sounds like it's failing in every circuit except knock and EST, but it maybe the same deal and it doesn't have the capacity to display all those codes. The PCM is looking really suspicious to me. I'd check to see if the "ECM-IGN" fuse is burned first. If not, I'd actually pull it, open it, and check it really close for burning or scoring. Pull the circuit board out of the case and remove the MEMCAL if you need to get a better look. I'd also smell it. It shouldn't really smell like anything. If it's got a burned smell or similar, that's also a good indicator when you don't actually see anything wrong.

    If your PCM ends up being the culprit, I'd go through and make sure there's no physical short to ground or water where it shouldn't be. The only thing I've experienced that can do this is the spark plug wires so I'd check those carefully boot to boot.
     
    Last edited: Aug 10, 2017
  4. usar17

    usar17 Full Access Member

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    All new spark plug wires last month. Hopefully ill get some time later today to poke around

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  5. 4WDKC

    4WDKC Full Access Member

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    If your TPS showed 85% not .85 volts thats why it wouldnt shift. Had a TPS go bad on my old truck caused it to not start without starting fluid, high idle, and tranny wouldnt shift untill relaly high in the RPM (2nd ran to 75). TPS was telling EMC it was WOT so it tried to run like it was WOT max rpm shifts, full fuel spray while running with blades closed made it open IAC to keep AFR right and WOT while cranking is clear flood mode.
     
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  6. usar17

    usar17 Full Access Member

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    Dead on. Unplugged the sensor and the truck fired up. On the way back from the store with a new TPS

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  7. usar17

    usar17 Full Access Member

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    All fixed thank you 4WDKC

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