1998 Z34 speedometer problem

[kc9cjy]

Hi all. I've got a 98 Monte Carlo Z34. Lately, the speedometer is acting up. While driving, it will just go nuts, and start rapidly bouncing all over the place...then it usually either just falls to zero, or to a random speed that is lower than I'm actually going, and stays there for some time. Eventually, it seems to fix itself and show the correct speed again. It's intermittent and I can't find a way to get it to appear on my own. Any ideas? It sucks not knowing how fast you're going!

[CEO Wrench]

Originally Posted by kc9cjy

Hi all. I've got a 98 Monte Carlo Z34. Lately, the speedometer is acting up. While driving, it will just go nuts, and start rapidly bouncing all over the place...then it usually either just falls to zero, or to a random speed that is lower than I'm actually going, and stays there for some time. Eventually, it seems to fix itself and show the correct speed again. It's intermittent and I can't find a way to get it to appear on my own. Any ideas? It sucks not knowing how fast you're going!

It's not likely to be the speedometer head; more than likely the sending unit in the transmission, or the ECM computer. There may be a trouble code registering the problem even if the service engine soon light does not come on. I'd get someone to download the codes first and then see if there is a good diagnosis to go on. If you need replacement parts, a good salvage yard should be able to fix you up. You can try www.car-part.com to find good sources.