I bought a 90 Camaro RS v8 automatic in December, when I got it occasionally the speedometer wouldn't work until you were going about 10-15mph. Never really a problem because who drives that slow.

Now the speedometer rarely works, on the freeway doing 65-75 it comes on most the time, but in town driving rarely.

When the speedometer goes out, I seem to get higher RPMs going the same speed. It also sometimes acts like it wants to come on and will hop up to 5mph or 10mph, sometimes higher, then lay back down dead to the world.

If the speedometer is working it also seems that the car runs smoother. Any suggestions?

[edit] when its working, and I slow down at a stop sign or such, when I accelerate it doesn't come back up

 

replace the cable. it pulls right out of your cluster, and unscrews from your tranny.

 

Alright, I've got my book and my toolbox. I'll see what I can do

 

The speedometer in a '90 is electric. No cable.

TBI? Has a VSS on the trans tail shaft, wires (2) go to a 4-OUT BUFFER box (under dash on passenger side). The outputs of the buffer box go to the ECM, speedometer, and ECM.

TPI? Has a VSS on the trans tailshaft, wires (2) go to the ECM. Out of the ECM to the speedometer and the cruise control.

Start with the VSS and gears that drive it.

RBob.