Truck problem...need help.

Discussion in 'Trucks and Trailers' started by proenterprises, Jan 17, 2005.

  1. proenterprises

    proenterprises LawnSite Silver Member
    Posts: 2,297

    Okay, so this morning im driving on the highway, and all of a sudden my check engine light comes on and my speedometer drops down to zero. Truck does not stall or anything, but I pull over. First thing I check is the oil, and it is pretty low. I add a quart and the level seems fine.

    I continue on the rest of my journey, truck seems to run fine, but the check engine light is still on. Also, the speedometer still stays at zero and the odometer has stopped ticking.

    What is the problem. I am going to take it by AUTOZONE and have them run the diagnostic test.

    ANYONE have an idea. Its a 1994 Nissan XE pickup.
  2. scott's turf

    scott's turf LawnSite Senior Member
    from NH
    Posts: 949

    my guess is a broken speedo cable if it is a machanical odometer.
  3. proenterprises

    proenterprises LawnSite Silver Member
    Posts: 2,297

    yes it is a mechanical one (not digital)

    i also posted in another forum, and they suggested that it may have been a computer failure, which also caused the check engine light to come on. coudl this be correct?
  4. xcopterdoc

    xcopterdoc LawnSite Senior Member
    Posts: 752

    A broken speedo cable or stripped speedo gear, will cause the CEL light to come on. With no speed input to the PCM, the computer will set a code.
  5. Albemarle Lawn

    Albemarle Lawn LawnSite Bronze Member
    Posts: 1,544

    Bad VSS

    "Vehicle Speed Sensor"

    Even though you speedo is not digital, it probably runs off a sensor, not a cable in that year.

    The VSS in most cars is actually an AC generator (like old bicycle lamp generators).

    The faster the speed, the faster the cycle. (Hz, or Hertz). The speedometer reads the Hz (cycles per second) supplied from the VSS.

    Could be gear or sheared pin to shaft on VSS, or connector/wire.
  6. proenterprises

    proenterprises LawnSite Silver Member
    Posts: 2,297

    any idea how much this will be to fix??
  7. rclay11541

    rclay11541 LawnSite Member
    Posts: 100

    can be alot but i would be carefull driving it for other than obvious reasons.
    If its an auto doesn't the auto tranny need to know how fast ur going?
  8. proenterprises

    proenterprises LawnSite Silver Member
    Posts: 2,297

    i drove it about 60 miles today. no problems, runs fine, why woudl the tranny ened to know how fast?
  9. greendave

    greendave LawnSite Member
    Posts: 219

    The on board computer uses speed input for many functions. One of them may be torque converter lockup. Drive it too far without speed input and you'll likely do damage. Do yourself a favor, DON'T go to Autozoo. Take it to a REAL machanic/technician and let him DIAGNOSE IT and FIX IT, not just pull codes and sell you parts. Gawd, I hate those discount auto parts sellers, that'd what they do - sell parts. Prescription without diagnosis is MALPRACTICE......

    ........gets off soap box, awaits replies....

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