Snakebit12

Help.

My daughter has a 98 ZX2 with 100k. Recently we have noticed the speedometer sporadically acting up. For example, today on the interstate with a constant RPM, I had the car at 70 mph and the needle suddenly bounced backwards reaching 20 mph before it bounced back to 70 - took maybe 10 seconds. It never bounced over the current speed...only under. And then it held at 70 mph for several minutes before going beserk again.

I have taken this to several shops with no success. A new VSS was installed - no improvement. Another garage recommended replacing the speedometer since everything else seemed to be working ok - I take that as replacing the entire instrument cluster. I am happy to do this with a used cluster and hopefully can find one with the same approximate mileage. But I am not convinced that this will fix the problem.

One item to note...if cruise is on while the speedometer falls back, the engine revs up to make up for the preceived loss in mph.

I could really use some advice.

John

 

backlash1

Hi John
And based on the fact that the engine tries to make up for a perceived loss of speed you could say it's a VSS problem, becuse the PCM is definitely seeing a VSS signal (though it's the wrong one), but if the sensor has been replaced before, then I would inspect the wiring loom and connectors before replacing anything else. Check for loose connectors, corroded pins or broken wires. I'm pretty sure your problem lies there. cheers
Marc