View Full Version : Speedo is going crazy.

05-08-2017, 04:58 PM
Hey guys, My speedo has been messed up for a few years on my 89. It bounces from 0-60 to 100 and back to zero. Constantly. Even in park. My Odometer works fine but the speed is screwed. It all started after I did a brake job on the front brakes.

Any suggestions on how to fix it? Thanks

05-09-2017, 01:25 PM
I've seen this another car before...I never tried to figure it out, but would suspect that either the speedo unit is damaged or the VMM sensor on the transmission needs replaced.

05-10-2017, 12:26 PM
I've seen before where the insulation on the wiring to the speedo sensor in the trans breaks apart, exposing the wires and intermittently shorting them out.

05-10-2017, 01:00 PM
My speedo has been messed up for a few years on my 89.

Regardless of what else you suspect/find/fix, I'd plan on doing the plastic gear repair to the head unit. The OE gears routinely age and fail - search here on best sources for the kit, or if you don't feel comfortable in there, there is one SC vendor that will do the job for you, once the head unit is out of the car, as I recall.