Defender 90 Temp gauge playing up

My temp gauge was on cold. Took the lead off the sender and earthed it to the engine. Ignition on and did did not move. Checked behind the gauge and found out it was disconnected. Put it back on and now the gauge after 5 mins of running is in the red...the engine is not overheating..and not running hot even after an hours journey down the motorway. Could it be the sender that is stuffed? Previous owner must have removed for some reason.
Advice from any member please.
Thanks

What 90 do you have there's a few different gauges and senders?

What engine is it and is it the original engine? Sounds like you hve the wrong sender.

warrior said:

What 90 do you have there's a few different gauges and senders?

What engine is it and is it the original engine? Sounds like you hve the wrong sender.

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Thanks for the reply.
It's a early 1989 2.5DT I just changed the sender yesterday and now when you turn the ignition on the temp gauge goes straight to hot within 30 seconds. Engine not running. I have seen posts where others say it's a bad earth. Any idea which earth? Any advice is appreciated.

Ritson Bentley said:

Thanks for the reply.
It's a early 1989 2.5DT I just changed the sender yesterday and now when you turn the ignition on the temp gauge goes straight to hot within 30 seconds. Engine not running. I have seen posts where others say it's a bad earth. Any idea which earth? Any advice is appreciated.

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Like warrior says, there are a number of different senders, at least 2 for 2.5td, different for Tdi etc. Maybe you have the wrong one. Also look at the gauge and its wiring, is it reading in reverse?
Also, why have you posted this in Members Vehicles section? You are much more likely to get help in Def 90/110/130, and it wont clutter up this area for those who wish to look at Members Vehicles

Maybe you have the wrong gauge not the sender,

I would imagine a bad earth would stop its rom working as they work on resistance to earth

I had an issue with mine which is a VDO gauge and sender, where it would climb above normal running temp when I turned the lights on, or the electic fan up front also sent it dicky. I fitted a braided earth strap between the back of the head and the bulkhead and all is good again now.