Th odometer works but the speedometer doesn't. There are are no fuses out. In an old car I would just replace the cable. But everything is electronic. Where do I start to troubleshoot the problem?

Edit: 2004 Rendezvous-V6

 

Try checking the fuses first. There might be one for the speedometer. Also, is there any lights on on the dash, like the service vehicle soon, ABS, and trac off lights? They indicate a bad wheel speed sensor that can cause the speedometer not to move.

 

Thank you for the reply. I'll check the lights on the dash as soon as I can get the car in my grips (it's my mothers car). I checked the fuses already. Nothing there specifically for the speedometer, but there were two or three that had to do with the instrument panel. They were good.

 

You're welcome. Keep us posted on what you find (or don't)

 

Don't think the resistors issues were the same as century regal. Could be the stepper motor as well but hopefully not.

 

Here's the wiring diagram for the Rendevous' IPC.

I know it might be hard to tell, but does your cruise control work?

 

There are no indicators on the dash. Everything appears to be just fine, except the speed. It was an intermittent problem a while back. For a couple of weeks it would register 100 mph, or the needle would be pointing straight down. Then it worked fine for a while. Now the needle points to over 100 or straight down, depending on how it feels at the moment.

I'll ask about the cruise control. Mom has a Garmin that tells her the speed, so she would know if cruise is maintaining the desired setting.
The dealer told her that the speedometer had to be removed and sent to the manufacturer to get fixed. Seems kind of extreme to me.

Thanks for the diagram, Travis.

 

That would probably be for what Merc6 was talking about the stepper motor..

That would be the very last resort, as that probably won't be real cheap..

Try hitting the dash just above the speedometer..there could be a loose connection, in the IPC. Also, you can try disconnecting the battery for a half hour. It should reset the computer back to factory settings.

 

We had one of our fleet vehicles (2005 9C1) with a bad speedo. Instead of not moving, it never stopped moving making it impossible and illegal to pace another car.