My speedometer has been acting crazy the last two days. I can be driving down the road at ~50mph and the speedo will jump from the 20s to the teens to 40s, all with no change in throttle or rpm. I thought that the VSS was loose but it's not. This is the only gauge thats not working properly. The led's lighting the speedometer numbers don't dim, the numbers simply jump around. Anyone have any ideas? BTW I'm running a Kpro if that makes a difference.

 

The speedo lead to the ecu is probably loose. This happens sometimes to cars running the Yellow Jacket or Yellow Box speed correction gadget...the plug starts to come loose giving a bad connection. I've had it happen on my Yellow Jacket when going over expansion joints or reflector blisters at highway speeds.

 

do you know which wire it is?

 

Take a look at the install instructions for Modifry's Yellow Jacket:

http://modifry.com/products/yj/Yellow%20Ja...202000-2005.pdf

The wire that comes loose on my car is the white one that connects to the blue/white wire from C101.

 

I haven't been able to find a loose wire. I checked the vss and all three pins on the sensor are putting out the right amount of voltage. I pulled the cluster like the factory manual says and checked the voltage coming in and the voltage is pulsing. I checked the connections, plugged it back in and it worked for a couple days and then it started reading wrong again.