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Okay, I need some ECM/PROM help ASAP!

Discussion in 'Chevy Trucks' started by SubUrbanMonster, Jun 2, 2010.

  1. SubUrbanMonster

    SubUrbanMonster Junior Member
    Messages: 7

    1993 GMC Suburban K2500 5.7 4L80E Trans.

    My ECM is 16147060, my PROM is 3074BAAY.
    I have two of these same Identical ECM's, one came in the truck, one was picked up from junk truck. My transmission hasnt had Overdrive since I purchased the truck. After multiple troubleshooting attempts, I ended up at trans shop getting a diagnostic. My computer operates my engine perfectly fine, but when applied with trans, the diagnostic tool reads my 4L80e as a 4L60e, which is NOT correct, now should it say that as my PROM is the factory PROM for 5.7 4L80e. My OVSS flashes and changes non-stop from 40-190 and cycles randomly to diffrent numbers inbetween.

    Diagnostic tool says my RPM's are 48. No, not 4800, or 480, but 48. Thats the truck Idling in park (dash tach reads idle at 700), along with my battery voltage reading in at a wopping 2.5 volts.

    This truck has some strange wiring in her n what not, old harnesses and relays from crap pepboys antitheft system i ripped out, but The truck runs and drives great, and its the same with either ECM plugged in.

    Why would the diagnostic scan show such insanely random and obviously inaccurate readings? Only code im reading is TPS not adjusted (just installed it this past weekend) and also Trans Pressure Control Solenoid (force motor) Current Fault? Im tired of doing battle with this damn thing, I need to atleast have the correct computer and PROM in this thing so I can fix my trans.

    Question for you all, do any of you recognize these symptoms here? Im going to be purchasing a brand new EPROM from GM online tonight, unless someone here advises me that that isnt the cause of my problem. I know its either my PROM is bad, or my ECM is bad. Gotta be one of the two. I really need some help here guys, I'd really appreciate it. Thanks!
  2. RacingZR

    RacingZR Senior Member
    from Maine
    Messages: 398

    Instead of throwing parts at the vehicle, find a good auto electrical mechanic and have them figure it out. Not a tranny shop or a dealer......an auto electrical mechanic! A good one is worth it every time. My $.02.......