46RE Issues (SHOCKER)

Discussion in 'Tech Info' started by 93ramW350GASR, Oct 8, 2016.

  1. 93ramW350GASR

    93ramW350GASR Junior Member

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    Ram Year:
    1993 Ram W350 Dually
    Engine:
    5.9 Magnum
    hello, my apologies for not first stopping into the introduce ourself section but ill get to that soon enough. right now, i need some dodge transmission and PCM expertise. Ive got a customers 1997 ram 1500 that we swapped trannys in due to a failure of the original. Blew a cooler line aaaaannnnnddddd continued to drive it. anyway! got a rebuilt trans with a stage one shift kit, as per customers request, and i am having issues with the truck shifting into overdrive leaving from a stop. i can watch it physically shift into overdrive from first on my live data scanner. governor pressure and duty cycle are all where they need to be. HERES THE DEAL! i had issues with the OSS reading crazy speeds so we took care of it and got it back to where it needs to be. however the vehicle even when stopped, will read a vehicle speed that will jump around from 2-400 mph. i believe this is where my issue is coming from however i dont know where or how to sort it out. there WAS welding done on the truck without the battery disconnected so stray voltage IS a possibility, however we swapped in a known good PCM and had no luck. so the original PCM is not damaged. the OSS wiring and sensor test ok and read properly on the diagnostic scanner. testing the mechanical sensor (on the transfer case which runs off of the plastic pinion gear) the harness to it is sending 5.13 volts on the supply wire and is ALSO sending 3.1-4.9 volts on the signal line with the key on.. not an expert in 3 wire sensors but that seems strange to have voltage coming IN on the signal wire. any ideas would be much appreciated. ive run out of alleys to try to troubleshoot. THANKS!!
     
  2. 93ramW350GASR

    93ramW350GASR Junior Member

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    Joined:
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    Ram Year:
    1993 Ram W350 Dually
    Engine:
    5.9 Magnum
    Update: even with the sensor completely removed from the vehicle im STILL getting a vehicle speed reading... so it has to be a circuit issue at this point? i should also mention i have no tach and an erratic speedometer
     
  3. dudeman2009

    dudeman2009 Senior Member

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    Location:
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    Ram Year:
    2001 1500 Sport with enough electrical modifications to make my brain hurt
    Engine:
    Magnum 360
    The truck probably has at least rear wheel ABS. The speed sensor from the differential goes to the ABS module, if that is the sensor that is reading voltage on the signal, i would suspect the ABS module. I don't believe the PCM receives and vehicle speed readings, even on trucks with a trans speed sensor in addition to the rear diff sensor. I think its the CTM that gets that signal, maybe the IC itself. If it has ABS, id check that first. You should be able to see if that is where the error is starting by just unplugging it and seeing if that speed reading drops to zero.

    I cant remember if 97 has two or just one speed sensor.
     
  4. DodgeTx

    DodgeTx Senior Member

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    Location:
    San Antonio
    Ram Year:
    2000
    Engine:
    5.9L
    That rear diff spead sensor can cause O/d issues as well I've read elsewhere. Also check the speed sensor on the tranny. They can be obtained online for less than $30 for both.
     
  5. dapepper9

    dapepper9 Senior Member

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    Location:
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    Ram Year:
    2001
    Engine:
    5.9L V8
    What do you know about the replacement trans? Is it used, reman, etc
     

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