Older Bmw: very strange Temp Gauge problem

[InYaMooey]

Small update:

Pulled the cluster (Ms Stopit) re seated the connectors, also untwisted the loom a little.

So far fault not happened today (10c ambient and this when it normally starts playing up)

So will see how it goes

Only downside is I’ve lost my hard earned 25mpg average

[Penelope Stopit]

Good of you to update, fingers crossed

No need for "Ms", she's a he

[InYaMooey]

Penelope Stopit said:

Good of you to update, fingers crossed

No need for "Ms", she's a he

Prefer Ms anyway

Update 2: I spoke to bloody soon !

Just went out again as now 8c and dial went up to max again

Just once on the drive a tap on the top of the dash sorted it but this only helped once !!! (It’s also still intermittent so could be a coincidence I suppose..)

Pulled dash pod and fiddled with wires/plug and nothing helped.

I’m thinking deeper in the pod/circuit board dry joint

I’m wondering if a little electrical contact cleaner on the plug or socket might help or possibly a tiny bit of WD40 ?

I’m reluctant to break the pod apart but might come to that ..

[chammyman]

Check the ecu plug. We find them frequently corroded with coolant wicking up the wires and corroding the ecu pins. Sometimes fine when cold but not when hot and vice versa.

[InYaMooey]

Thanks for that, I have been in there previously and re seated the plugs before (can’t remember why) but will check again.

It behaved today (but only 11c) this was after I pulled the pod late y’day and had another fiddle (read tapped the back of the pod on the temp gauge side)

Fingers crossed again

[InYaMooey]

Problem solved mods please can you mark the title as solved ?

Just to update and thank all for ideas contributions.

It turned out to be the Thermostat !!

I pulled it for inspection and saw it was not closing 100% (1-2 open) so thought possibly the main ECU was detecting a slow warm up and defaulting to max but couldn’t work out why on some journeys the gauge would revert to normal position.

Had ordered a new 95 deg stat (long story) but this didn’t have the extra connector so didn’t fit it.

As my original stat was out I broke it down and refitted without the internals so I could use the car to pick the new original 105 deg stat.

The gauge started behaving !! So now thinking not a slow warm up fault..

Anyway now all sorted and has been perfect the last few days

The stat appears to have an internal electrical contact which was very dirty or possibly not making a good contact due to being slightly open.

I also broke the socket off to see inside and looks pretty bad.

Non the wiser what was actually causing the fault but now thankfully sorted out.

Will attach some pics for reference

Thanks again all









And the new one





Still can’t work out why it was ambient <10c related

Edited by InYaMooey on Thursday 18th March 19:54