300 tdi temp gauge goes high with lights on

300 tdi defender ,temp gauge sits around the middle until I put the lights on (always dark when I'm driving atm !) She gradually creeps up close to the red

Gauge creeps back down when I turn the lights off

I assume it's an earth fault, I've tried a jump lead from the small earth on the bulkhead to the battery

Has anyone had this an if so where are the earths likely to be causing the problem ?

Thanks

Just make sure you are not having an actual temperature increase in the engine, if cooling system is a bit iffy it only takes a bit more load for temp to creep up. Check with IR meter.

"I assume it's an earth fault, I've tried a jump lead from the small earth on the bulkhead to the battery"

Did this temporary link cure the issue and confirm it is an earth fault?

Litch said:

"I assume it's an earth fault, I've tried a jump lead from the small earth on the bulkhead to the battery"

Did this temporary link cure the issue and confirm it is an earth fault?

Click to expand...

No that didn't cure the problem but the gauge goes down when I turn the lights off so I assume it is an earth fault