Having a temperature gauge issue on my 97 XJR. Gauge operates properly for a while and then will shoot up and peg at hot. Will fluctuate a little sometimes but pretty much stays pegged once it goes there. The funny thing is I use an Ultra Gauge to monitor temp and the operating temp is always fine. Leads me to believe I may have a grounding issue with the jaguar dash gauge but where? I am perplexed that the Ultra Gauge reads normal operating temps while the gauge on my dash is going from normal to pegged hot. No check engine lights going on either. Your thoughts? Thanks

 

Replace the sender, it's shorting internally.

 

If the sensor were shorting internally, the Ultragauge would exhibit the same fluctuation. You may have a pin not making a good contact or, as you mentioned, a ground problem. Disconnect the neg. battery cable, then clean the ECM and inst. panel connectors with electrical contact cleaner.

 

There are two temp senders - one for the dash and one for the ECU.

Replace the one for the dash.

 

That's interesting. The only one I have ever read about is on the crossover pipe. Where is the other one located?

IGNORE the above, I thought I was on the XJ8 forum.

 

The two senders are side by side on top of the water pump on the XJ6.