2001 XJ volt gauge creeps to max!!!

I got a call telling me our 2001 XJ's volt gauge creeps to max, the radio shuts off, then goes back to normal. It keeps cycling like this. What could cause this before I go start chasing my tail?

IF you are familiar with a VOM (multi meter); you should do some testing of system voltages to verify what you are seeing on the instrument cluster...
There could be several things to cause this....
Bad instrument cluster ground, loose connections or dirty connections battery cables or charging lead from alternator, or sensing lead for ECM since the ECM controls the charging rate of the alternator....

That's what I figured. I just didn't know if someone else had fought this before I go tackle it.

Put new ground straps on it and it hasn't happened yet (she has 40 miles on it since I worked on it)

Sounds as though you might have the problem fixed....

Future reference:
ALL of the OBDII dash readings are indirect. Every supposed guage is just a readout. The PCM takes all the readings and passes them though a communication buss, and they are then decoded and displayed. Take them with a grain of salt.

The radio part creeps me out. The 2 gounds I would hit are the battery to the fender, and the engine to the firewall.

Ron