ok here it is, 86 TA tpi, everything is stock, the problem has been there since i got the car. the speedo is dead, all the other gauges work, the car has cruse also, and it works. when i turn the car off the speedo jumps , then comes back to 0. my car has the electronic sensor in the trans (700r4), not the cable. i also cant find any schematics or diagrams for the wiring (i have the chiltons and hanes manuals , both just show cables) is there any common problems with the sending unit in the trans,or wiring that anyone knows of? anyone seen this before? thanks.

 

Electric speedo's are driven by a small electric motor. It's a possibility that after 16 years of faithful duty, it finally went into retirement.

If your cruise is working & you're not getting a Check Engine light, your VSS is most likely fine.

You may want to pop your cluster out & test the motor on your speedo. If the motor works by jumping 12v to it, then there's a chance of a short in the power. Or, someone could have a better idea of where to start for you.

 

hey thanks, thats better than i've gotten so far, actually i tried to pull some codes out the other day and found the ses light is burnt out (it's still a project car so i 'm not driving it yet or i would have noticed) so i have to pull the cluster anyway, i didnt know about the motor for the speedo so i guess i'll try it when i get there. i talked to a guy yesterday that said something about the wires in a connector near the sensor like to get coroded and /or pull out of the connector he said it happened to 2 of his third gens, so i guess i'll look there too, ever heard of that? thanks for the info!

 

if you have a dmm you might also check the vss buffer/DRAC module for input from the vss and output to the speedo motor. '86 model might be a part of th instrument cluster or possibly seperate. if seperate it will be a white plastic case approx. 2x2" wth one plug with lik 6 wires. located behind the dash between the dash and cem. i should have the factory manual at work. i'll gt you th schematics if you ned them.