1991 ZR1 Help no speedo, Code 24
Thread Starter
3rd Gear
Joined: Nov 2010
Posts: 3
Likes: 0
1991 ZR1 Help no speedo, Code 24
Hey guys I have a customers car here it is a 1991 ZR1. I am a body shop so this stuff is a little confusing to me basically the car has an intermittent check engine light a permanent service ride control light the speedometer isnt working(Turns on but sits at 0). Pulls code 24 out with a scanner saying speed sensor not communicating and when the check engine light is on there is a drop in power from the motor. The car is beautiful and has less then 50k miles on it. Good customer of ours and I told him I would try and figure it out but not having a lot of luck. It seemed like a ground issue but i've checked the 2 main grounds i can find and they seem ok. Anyone have any ideas on what may be triggering this?
Racer
Joined: Oct 2002
Posts: 372
Likes: 1
From: Corunna Mi
A couple of quick checks would be to look at the plug for the speed sensor towards the back of the transmission. Bad connection or unplugged? If all looks good the only other easy check is to unplug the Ride Control connector in the well behind the drivers seat and see if the speedometer now works. If it does the ride control is shorted out. All of the problems you listed are from a loss of VSS signal to the ECM. This is the code 24. Once the code sets on the ZR1 you will have the reduced power (same as if the valet key is turned off) and the service ride contol light will come on. If all checks good the next step in the FSM calls for a signal generator at the VSS plug to check the wiring. The speed sensor it self may be bad but without equipment I don't know of a way to test it. One thing you should know is if you replace the speed sensor and the code 24 is gone along with the check engine light and the speedometer is now working, you will still have the service ride control light until you reset the ride control computer. Just post up and we can work thru that as well.
