BryanE

Have 98 Grand Cherokee Laredo ZJ, 5,2l 4x4, My question is Speedometer needle is stuck at about 45mph, where should i start to fix issue? also, will that not allow cruise-control to engage? get no indicator light on gauge cluster to indicate on or off. thanks for help in advance

Noah911

Have you tried the diagnostic test to see what the speedometer needle does? I believe you are supposed to hold down the odometer trip reset button before when turning the ignition key into the RUN position. The gauges needles should all do a sweep.

BryanE

Really, Didn't know that... my first Jeep. Will try that. if, for some reason that doesn't do it. whats next?
Thanks

Noah911

A few things...

It might fix it and it may not? I would then undo the battery and reset the PCM to try that next though.

Scanner to see if the sensors are sending a signal. If they are... then, it may be the cluster itself is bad, or possibly even the cruise control unit.

Noah911

Worst case is probably the Body Control Module (BCM).

(edited)
I cannot recall which if the two main computers are involved in controlling the speedometer function on your ZJ? If it is the Powertrain Control Module (PCM) or the BCM? I would have to look it up. I do not think it is either of these though.

BryanE

Thank you very much... this information is very helpful. now i have a direction to move into.

Noah911

There are a few speed sensors. The ZJ Vehicle Speed Sensor (VSS) is located on the transfer case tail housing. The VSS is the speed sensor relaying the information for the speedometer reading. The other speed sensors on the transmission are for shifting and other reasons.

Noah911

I mentioned the VSS since this would make sense for no longer having a cruise control function. You cannot set cruise if the speed is not being relayed accurately, or if it is stuck at a certain reading.

I think this would throw a code? A code does not always get thrown though...

BryanE

Exactly the information I was hoping for.. this will be very helpful in resolving the last few issues I'm having with my Grand Cherokee... Thank you very much.