Got a real problem here

[Michael Mystik]

Hi Guys , I'm Mike from toronto , got a real technical problem here with a 1997 BMW 318i.  I've recently re done the whole cooling system in this car , and it runs mint , the engine temp holds steady , lots of heat , separate digital climate control works perfectly etc.  but I'm having a problem with the temp gauge on the dash , it fluctuates between regular temp (12oclock) and then drops fast to cold (9oclock)  I've changed almost everything involved in the cooling system to narrow down the possibilities ;  here's what I've changed

1 thermostat
2 water pump
3 temp send sensor
4 heater valve
5 heater core
6 cluster

The car had this problem before I changed any parts , and as of right now the car runs like new , but this temp gauge seems to have a mind of its own .

I've Blead the system , flushed the coolant , no leaks , no air , scanned the car while I was driving and problem was occurring and still no more info to go on.

I keep hearing that there is something related to the gauge , that sits above the glove box , but that might be all specuation ,

I'm wondering if any of you guys know where I can begin to look for a diagnosis on the problem

Any help would be greatly appreciated !! I called the dealer and they said change the Ecu, but  not convinced that its that !!

Cheers
Mike

[Nelson_40]

Not 100% sure if this applies to the E36 as well, but you might have a bad ground/other connection at the rear of the cluster.

[Michael Mystik]

That's what it seems like , but there is not much going on back there , 3 clamps , and a few screws ...... Is there something in particular wire wise that I should look for ? Obviously a damaged wire but otherwise ?  Could a screw cause a short ?