Temp gauge

[dpetersen]

Gday guys!
So a funny and not so funny story;
My temp gauge has been showing my car running hot for the last few months. I changed the thermostat and did a coolant flush/change, didn't make a difference. Yesterday I worked out why it's playing up!
Because it's 400ks for me to get to town I always drive with my headlights on and a/c on as its about 40 degrees here at the moment. I always turn the headlights and ac pretty much as soon as I start the car. Turns out I have an earthing issue. Only worked it out yesterday but if I turn the headlights off the gauge goes down, it goes down again if I turn the ac off. If I turn the high beem on it says the car is basically overheating. Can't believe it took me so long to work this out!
Anyway what do you guys think is the best way to rectify the problem?
2003 gu zd wagon.
Thanks guys!

[threedogs]

Re -do any visable earth straps in the engine bay even run a new one from the battery to the firewall.,
Well thats what Id do, good to see you finally sorted it.
Had a similar problem with my other 4x4 brand new VDO temp gauge , ended up being faulty gauge
after jet coating exhaust, larger radiator , john bennet water pump still getting hot GGRRrrrrr
But have the mighty ZD30 now and all is good he he

[4bye4]

A GU with an earth issue - that's unusual. Probably corrosion on the earth side of the temp gauge, so it earthing through the earth to the aircon and lights.

[the evil twin]

Check the sensor wiring for corrosion, dodgy connection.

Try adding another earth strap from the existing point to the chassis and chassis to body at the front RH.
There are heaps of spots in that area to make it easy
You can get short pre-terminated leads at any spares joint for a couple of bucks.
(even if that doesn't fix it the extra straps are worth doing)

If neither fixes it then the fault might be in the cluster.
As a point of interest does the gauge flicker at all with the indicators on?

[dpetersen]

Thanks for the info guys, will try it out and let you know how I go.
Evil twin, na the gauge doesn't flicker at all