I`ve got a 95 defender and whenever you put the lights on, the temp gauge climbs from the 12 0 clock position to the red whithin a minute or so. Worried me the 1 st time it happened as i was on the m6 with about 25 miles to the next junction. I stopped on the hard shoulder and opened the bonnet for 10 mins. When i restarted the 90 the gauge read normal but as soon as i put the lights on it rose again.
Still hav`nt got around to finding the fault as the gauge stays at 12 0 clock with the lights off