Code P0500

On my way down to Daytona Beach this morning from Jacksonville to see the Jeep Beach bash my XJ through something new at me.

I was running with the cruise control set at 70 MPH +/- listening to my favorite FM oldies music with no care in the world. About 20 miles into my estimated 100 mile trip the XJ suddenly down shifted and accelerated as if the pedal was pushed to the floor. The speedo was reading 35 MPH not the 70 MPH that I had set it to. This was on a perfectly flat I-95 South bound. Just as I was about to take corrective action the XJ decelerated as if the pedal was released so the vehicle could free wheel. The speedo dropped to 0 and the check engine light was lit. The cruise control ceased to operate and so did the MPH gage but every thing else worked great. I pulled off at the next rest stop and crawled under the XJ to check the wire connection. I also checked where I could under the hood but found nothing obvious.

The rest of the trip was uneventful except for the fact that I now have no speedo and no cruise control. I had to pedal the accelerator for the rest of the trip down and back home using a GPS as a speed indicator. Now all I have to do is go on a gremlin hunt :eyes: and evict that no good so and so.

What does P0500 indicate?

P0500 no vehicle speed sensor signal.

Digger87xj said:

P0500 no vehicle speed sensor signal.

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Thank you Digger87xj.

I got under there after work and removed the speed sensor. The shaft at the base of the actual electronic unit is worn and spinning in the drive gear. I could turn the shaft with my fingers and get the speedo in the dash to read. I should be able to get the electronic unit from 'U PULL IT'. There are always several XJ's there if different years and options. This is also a good time to replace the 39 tooth gear set there now for some 37 tooth to fit with the 31" tires I will be using soon.