i have a 94 honda civicex coupe. i was havin an issue with my idle, it was idling low so i replaced the TPS sensor. when i replaced the sensor i took it for a spin and the idle was fine, but i noticed my spedometor was at 0mph and it jumped up to 30mph allof a sudden and then dropped down again. it does that when im driving. cwhat could of cused it to stop working or what can i do to fix this

thanks

 

My 94 does this when I am hard on the throttle. It tends to bounce around at higher speeds to. I am thinking that the problem is the VSS sensor seeing how I grabbed one out of the junk yard.

 

Either your speed sensor on the trans has died, or the circuit board on the back of the spedometer is failing or has broken solder joints. Search the site, there are plenty of people with procedures for testing this type of thing.

 

Inspect the connector for the VSS, I see a lot of them with water damage cause this problem. The VSS uses an amplifier in some cases that can cause the speedo to bounce erratically. I would inspect the connector and wiring in that area, and substitute a known good VSS.