speedometer problems

[jeff1953]

Early 1999 Chevy Tahoe 4x4, my speedometer does not work, I have changed the speedometer, front wheel speed sensor, changed speed sensor in the transfer case on passenger side, is another sensor I have not found or any other idea that might help me get it going. Thanks for the help.

 

[Phillip Buessing]

Does the transmission shift correctly? Any codes? The PCM gets its speed signal from the speed sensor on the rear housing(output shaft) of the transmission(2wd) or t-case(4wd).The pcm then sends a signal to the speedometer. If you had a speed sensor bad the transmission would not shift correctly.

 

[98chevy2500SS]

Like @Phillip Buessing said, check for codes. Does your tach and odometer not work either? If all three items don't work, it's probably an ignition switch causing this issue.

 

[Schurkey]

Connect scan tool, use scan tool to control instrument cluster. The tool should be able to swing all the gauge needles from bottom of scale to top of scale on command.

Any that don't work could be faulty ECM, faulty wiring or connections, faulty cluster circuitry...but are most likely faulty stepper motors.