fuel and temp gauges not working

[andydormer]

Hello all. Help needed with fuel and temp gauges suddenly not working. 1984 1.9DG.

I’ve removed the dash cover to access the back of the temp gauge and with the ignition on (not engine running) spanned the ground (middle) terminal to the 10V terminal and the multimeter reads 9.96V. When I span the middle and other side (temp signal) it reads the same: is this right or does it suggest a short?

Battery reads 12.6V.

With a piece of wire I’ve shorted the ground to each other pin and the temp gauge doesn’t move.

When I earth the cable connected to the thermostat sensor (yellow and red insulation) again no change to the gauge (with the ignition on).

When I turn on the ignition the LED flashes for a few seconds then stops flashing. Header tank is full to brim.

Does this show the gauge faulty or do I also need to test the voltage regulator as in the wikihttps://club8090.co.uk/wiki/VW_Electrics_Non_working_temperature_and/or_fuel_gauges" onclick="window.open(this.href);return false;

Also, I need to check the fuel sender is connected properly, so will have to drop the tank when I can. What’s the minimum volume of fuel needed in the tank for the gauge to register? I think its near empty so will top up after checking connections.

Advice and knowledge appreciated.

[a1winchester]

The guage takes about a week (I exaggerate) to move up to it's indicating level, so you may need to be patient when checking the terminals.
Also, there's a huge inaccuracy when the fuel level gets low. If you aren't on level ground, you might find it says empty even if not.

[andydormer]

Thanks for that, will try again tomorrow and be more patient...

[andydormer]

I've sold my van now, but thought it would be good to put up on here how I fixed it.
I replaced the temp sender in the engine bay as the connection was a bit damaged and soldered a new connector to the wire. No joy for either gauge.
I put 2 more gallons of petrol in (had previously drained the tank and knew the level was very low) and hey presto that fixed it.
Am thinking there was not enough petrol in the tank to raise the float and register a voltage. ??

Maybe someone should fill a tank from empty and conform how many gallons it takes to make the petrol gauge register and put this info on the wiki??

Would do it myself but, like I said, have sold the van. Am now in the process of tidying the garage and selling off the spares I kept