Hi all. Hope you are enjoying your Memorial Day.
I was planning some cleaningg and touch ups on my 2008 XJ8, but now I have an issue to handle.
I plugged a 12v vacuum cleaner into the cigar lighter on the center console. The plug came apart when I pulled it out and the center contact caused a spark, shorting across the contacts of the lighter receptacle.
Now the red temperature warning LED on the dash is on and the engine coolant temp gauge right below it is not working.
Any suggestions? If just a fuse, which one? And what else is on that circuit?
Cheers,
Dwayne

 

Front and rear cigar lighters are fused at the rear power distribution box - F43 and F44, both are 15A fuses.
Neither fuse feeds anything else other than their respective cigar lighter, so no direct correlation to your temperature reading errors.

Temperature sensor is directly connected to ECM which interprets resistance changes, then communicates to the instrument cluster via CAN Bus to give instructions as to the appropriate readings to display.
No idea how you would have introduced this effect by shorting the cigar lighter socket, unless you managed to create a earthing problem with the high current pulse.
Earths are a frequent issue with our cars' sensitive electronic systems.
I would start by carefully checking earthing points both in the cabin and under the hood.

 

So it turns out that the sparking at the lighter receptacle caused an OBD code P0116 error. After I cleared that, everything went back to normal.