Speedometer Problem

**GTPOWER** · 07-22-2008

My speedo quit working a week or two ago and my tranny started acting funny because of it. I changed the speed sensor today. The old one had metal shavings on it. The Speedometer is still not working though. Any ideas?

**edp** · 07-22-2008

To be honest, I don't believe your trans would start acting up as a result of your speedo crappin out. It's more than likely you have two problems here.

Although GM has had a lot of problems with clusters and we do them like crazy I havn't seen any grand prixs affected, but that doesnt mean that there aren't any. Usually when theres a problem with a speedo or IPC they are usually replaced, theres not much you can do with them unless you take one apart and are a techie.

As far as your transmission goes I would drop the trans pan and check for metal. If you have any you may need a new transmission or to rebuild it. However if you wanna risk it you may be able to get away with replacing the transmission filter and cleaning off the pan real good. You never know you may get lucky. Have you experienced any weird shifting or slipping?

**Sabrewings** · 07-22-2008

Originally Posted by edp

To be honest, I don't believe your trans would start acting up as a result of your speedo crappin out.

It makes perfect sense. The VSS (vehicle speed sensor) is used by the PCM to decide when to command the transmission to shift when not under hard acceleration. Under hard acceleration it uses the engine's RPM to decide when to shift.

**GTPOWER** · 07-22-2008

The transmission shifts firm at every shift. When you first start it up the first shift from first to second takes awhile cold or hot. I have to run it out to 3400 rpm to get it to shift.After that initial time every shift seems to be at the right rpm but it shifts very firm.

**GTPOWER** · 07-22-2008

Also I have a hud and that does not work either. Are these run off of the guage cluster? Should I change out the cluster and see where that gets me?

**edp** · 07-22-2008

hmm, it still doesn't make sense that the speedo crappin out would cause it, it would make sense that the VSS crappin out would cause the speedo to go and the trans to shift weird. I wonder what codes they have...