temp gauge

[blurb55]

ok got bored and started dismantling - devil & idle hands etc.

Have removed temp gauge (quite easy Steve if you are careful and gentle)

Put a small voltage across the light which flashes as it did in the van and then across the gauge itself which glided gracefully to max.

So, where do I start to find the breakdown and can I test the sender when its out of the van?

Ta for help so far, would not have had the bottle to pull stuff apart without guidance from Steve & Ghost.

More beer at Vanfest = "frelling" dear trip!!

[Grun]

Paul,
I don't want to jump in and be a nuisance but as ghost has not yet replied..... I think you have proved the gauge moves when a small voltage is applied, but that it does not react when it is connected to the normal terminals, and the wire at the sender is earthed (ignition on).

I may well be wrong (nothing new there!) but this must mean a break in the circuit from gauge to sender. As ghost says the 14 pin connector to the flexy printed circuit below the cowl (cover) top of dash you have removed is number one suspect. Haynes shows wire is coded yellow / red pin No 6

Like ghost I have a couple of soldered wires repairing the printed circuit foils where it bends to enter the connector. Look in that area.

Mike

[blurb55]

Hi Mike, cheers for advice.

Went back to A Level physics and thought if I rig a separate circuit - 9v battery, sender unit and gauge, there should be an open circuit as the bi metallic strip (assumption) in the sender is open. Boil the sender on the stove and and the circuit is complete.

In my simple mind this shows that the gauge works, the sender works so it must be the spaghetti system.

Next plan is to take a bell tester to the wires running front to back and check they are complete (the chimp with the hammer melted all sorts of stuff with his gas axe getting the exhaust nuts off - inlet manifold for coolant which started this whole escapade!!).

If this show them to be complete it is then the printed circuit on the plastic sheet and where it connects to the multiconnector.

I may bypass this if it appears to be the fault and run the cables directly into the gauge.

Thanks for help,

Paul
AKA W. Heath-Robinson.

[Grun]

Good thinking Paul,
You may find that the sender is of the thermistor type, and that the resistance will be high at room temperature, and will drop as it heats up.
Don't have anything definite on that but could be.

Have fun, and do let us know the results

[blurb55]

Well the boy done good, we are over the moon.

Traced the cables and worked round having tested each circuit I disconnected and reconnected all of the teminals in the system, making sure each had a good contact.

Also used very fine wire wool on the multi connector at the back of the dash to clean up the terminals - very gently though.

Once I had done all of these I put it all back together and when I shorted the sender cables - hey presto! A working temp gauge.

I have now put George back together and am starting to go through the cooling system one last time.

Huge thanks to those who offerred help - Steve (Mocki), Ghost & Mike (Grun).