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speed sensor problems

Discussion in 'Mechanic and Repair' started by start2finish, Sep 23, 2006.

  1. start2finish

    start2finish LawnSite Senior Member
    Posts: 497

    We had to go through the tranny on our c7500 dump

    cat 3126 engine,
    fuller FS 6306A transmission

    we are not getting signal from the speed sensor, we tested the sensor with ohm meter and it checks out good, even bought a new one and tried it. Pulled the plug on the ecm and tested pin 32 and 33 which are the speed sensor wires, they are good.

    we are getting no power with load and this is a symptom of faulty or erratic speed sensor, also the spedo doesn't work now. I wonder if something was misplaced in the transmission, but the tranny shifts smooth up and down the pto works great. any ideas, I have given up and a local shop has the truck, they have spent two days on it and do not have it fixed.

  2. papaseven

    papaseven LawnSite Member
    Posts: 13

    Pull a schematic on that circuit from Mitchell and check every connector in the harness for moisture and fit.
    There are some issues on that cluster going bad also. It can cause some noise in that circuit and cause drivability problems without throwing a code.
    Your scanner may or may not interpret this as no signal from the VSS.
  3. start2finish

    start2finish LawnSite Senior Member
    Posts: 497

    the trouble shooting ifo leads to no speed sensor or erratic sensor, but finds in the wiring harness or plug. We have taken it to a professional shop and no leads, just more costs. I am at a loss to who to try next. If we take it to CAT and they tell it is in the tranny, what next?

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