When it gets cold, usually below 10 degrees, my speedometer will drop to zero sometimes. All the other gauges work fine. Last year I took apart the dash to fix the gauge cluster because all the gauges would die randomly, so that is fixed.

Is it possible that the speedo gear is not turning all the time when it gets cold enough? When the jeep warms up, it doesn't always come back to life. Sometimes it will work fine and then drop to zero all the sudden going down the highway. Sometimes it will bounce up and down for a few seconds. It only acts funny when it gets well below freezing.

Should I start by taking out the speedo gear and making sure it is not all gunked up? Or does this sound electrical?

 

I would check the gear. It's probably because like you said it's getting below freezing.. That's hard on parts

 

VSS probably shot, or going......easy R& R , mine usually 20-30K of driving, mostly due to heat.....however, the one from dealer lasts a lot longer, but they are more expensive $75.00 vs. $29.00 from Autozone/O'reilly.


does the speedometer work when truck is up to temp? or is it still intermittent/fail when truck is warm?


mine would bounce around and then die no matter what temp outside was.


the internal speedo gear is pretty resilient, I would replace the VSS and see what happens


good luck!


cpnwrench

 

It'll drop out even when engine is at running temp but only when ambient temp is below freezing. Thanks for the advice.

 

The VSS isn't in the engine or even close to it, it's in the tailcone of the transfer case.

 

OP you didn't make mention any information about your jeep which is very important in having us help you. Now with that said, go under you hood, look at the oil pressure sending unit and check its wiring. I had a short on the wires once and my speedo, and yes it's in the Tc tail cone, was acting crazy until I redid the wiring

 

Jeep is a 98 4.0 auto.

I just put a new oil pressure sending unit a couple months ago. I will take a look at the wiring.

Can the VSS be cleaned and possibly function better? Or should I just plan on replacing it?

 

You can take it out and look at it. Do think it can be cleaned. It's a cog that spins with the output shaft.