Electrical 2001 GT Speedo/Odometer Inop

Discussion in 'SN95 4.6L Mustang Tech' started by mikeythebull, Nov 30, 2012.

  1. Speedo is Inop altogether and Odometer lights up but isn't changing. Engine code read: output speed sensor malfunction. Also just had trans service and pilot bearing replaced.

    Been doing a little research and so far here is what I have done:

    1)Checked fuses with VOM, but the odometer has power so it is not a fuse.
    2)Pulled and replaced VSS, the engine light cleared but the problem remained.
    3)I have a Brothers Speed Calibrator and the car which I purchased used most likely had different gears installed, but the rear diff was replaced under warranty while under my possession.

    I guess my question is:

    Is the speed calibrator most likely the culprit, or could a wire have been pulled loose by the mechanic?

    Do i even need the speed calibrator since I have stock gears now anyways?

    Any advice would be appreciated!
  2. Might be handy if we knew the Model year of your car. 98 and older uses a worm gear driven VSS sensor. 99+ uses a no contact OSS sensor.

    Good idea to check the ground behind the center console. It's frequently messed up during a radio install.

    Is it possible that when the transmission was put back together, the OSS reluctor ring was left off? You should be able to see the teeth of the reluctor wheel through the hole where the OSS sensor is.

    If this is a 98 or older, have you inspected the plastic gears of the VSS sensor? What about the worm gear inside the tail shaft? Is it in place?

    If this is a 99+, check out the following thread from allfordmustangs.com.


    How to repair a Ford electronic cluster from www.f150online.com:
  3. Thanks for the reply. I did read over both those forums already and the car ran fine for over a month so the reluctor ring was not left off...the car is 2001 GT 5 speed by the way.

    To me the most likely problem is either a wire got damaged or the speed calibrator went sour. The wires from the calibrator run underneath the bracket that bolts the tranny to the frame (from the shift tower). my first thought was the wires were pinched under the bracket but under inspection they look ok.

    How about my question? Do i even need the speed calibrator if my gears are stock?
    Can I just remove it and see if that solves the problem???

    Also I am having two issues, the speedo and the odo aren't working. All these other guys have either one problem or the other, not both.
  4. +1 on the damaged wire theory. Perhaps it has touched the hot exhaust.

    As to why there's a Speedcal with stock gears. Is it possible that someone has used an older VSS style transmission and the Speedcal is needed to convert the signal?

    Also, if someone used a transmission from a 2004+ transmission, the Speedcal could be used to adjust for a difference in the number of reluctor teeth used on the 2004+ model year.

    But if the transmission is corrector for your model year and the rear end gears are stock, I agree that a SpeedCal should not be needed.

    OBTW, if the OSS signal is missing this will cause the speedo and ODO to not function.

    In general when trying to determine if there is a cluster, PCM, or OSS sensor problem the easiest way is to use an ODB2 scanner to monitor the car's speed. If the PCM speed is correct, look for a cluster problem.

    If the PCM speed is incorrect, look for an OSS sensor problem or a wiring problem.
  5. Thanks wmburns this is good stuff. My trans is the TR3650 so I may just eliminate the SpeedCal - However before I do all that I will take your advice and monitor the speed on my scanner to determine where the problem is. Much appreciated!