I have a quick question that would appreciate a response from anyone:

I have a 1994 Z28, LT1, 6 Speed that has been sitting for an extended period of time. When I went out to start it the Speedometer has decided to sit pinned over past 150. I tried giving the cluster a wack to no avail and when driving it doesnt move either. Has anyone else ever experienced this and can you give me any trouble shooting advice for where to start?

Thank you!

 

I would start by checking the connector at the speed sensor, located at the tail end of the trans (drivers side), to make sure it's connected. I'm not sure which direction would be indicated if it were disconnected (0 or 155+ MPH).

Secondly, with the cable unplugged, measure the reference voltage at the connector's yellow (+) and purple (-). It should be approx. 5.0 VDC.

If it turns out to be the speed sensor, its cheap enough and easy to replace. The sensor is about $15 at an auto parts store.

 

There is no pulse signal if the harness is disconnected. There is no pulse signal if the reluctor wheel on the tranny output shaft is not turning. The pulse signal is processed by the PCM, and that's where the signal that drives the speedo originates.

Sounds like a problem with the speedo.

Since this isn't an "engine" topic, let's move it to the correct forum.