Fuel and Temp Gauge

[mush145]

Hello,

Both the temp and fuel gauge have been slowly failing for about 2 years on my 86 Devon. I have been told that the printed circuit board might be at fault. I have replaced all of the sender untis to no avail. The questions is can you buy replacement circuit boards? I have done a couple of searches but could find nothing. Your help is much appreciated

[AngeloEvs]

In what way are they failing?

[mush145]

Both of the dials never move anymore. They used to move and work but slowly have stopped working

[AngeloEvs]

Take the pod off and check it properly before spending time and money trying to source another S/H membrane (and you usually have to buy the complete dash anyway!). The regulator is common to both gauges and could be the problem and not necessarily duff either since the legs can tarnish in the socket. Take the pod out and start by giving it a good visual inspection, particularly the edge connections and check the tightness of the nuts that secure the gauges to the panel. Do you have a multimeter? I f you do then can talk you through the various checks and how to do them!

[mush145]

Thanks for the reply I do have a multi meter so any advice would be really useful. Sorry for short replies but in a very dull meeting answering on blackberry!

[AngeloEvs]

Look in the fuse box, do you have a relay marked 43 and third along position wise? If you have you can check the Voltage regulator here before removing the dash pod, take a peek and, if yes, will post details on how to do the check!

[mush145]

Thanks for the advice will check on Thursday when I am back home

[rgeneration]

ahh that's poss gonna be the plug that goes to the instrument binnacle, it sandwiches a very 1980s ribbon design copper cable plate ee things and go green have look. ow pinch white clip to remove speedo cable. worth a go as it got to come out whatever. hope that of use?

[mush145]

Finally had some time to look at the van. And it appears that I do not hae a 43 Relay in position three in fact there is nothing there? Could this be the problem?

[CovKid]

Doubt it. My money is on AngeloEVS's first suggestion or a poor connection between clocks assembly and wiring loom (ie the multi plug)

[AngeloEvs]

Your van may have the module located elsewhere as '86 was the crossover year when 43 was fitted in the fusebox. If your van has ceramic bullet fuses then its not in the fusebox, if you have the plastic mini fuses then you should have one fitted as it warns you of coolant loss. You can still check the regulator by removing the dash cover (just pulls off) and placing your multimer (set to DC Volts and a voltage range suitable for 12V reading).
across the temp gauge securing nuts (shown below but ignore the little pcb on the top, just something I was testing).

With ignition on............

Voltage across the Green - Black (centre nut) should be about 10v.

Voltage across red and black should be around 12.5V


The regulator is shown in the picture but yours may be mounted in a slightly different position. Check that the nuts are tight, appears these can vibrate loose but pod needs to be removed if the voltages are OK. You could also short the nut with the green wire to the black and gauge needle should start to rise slowly....don't do it for too long though otherwise the gauge will overheat, just enough to see it climb to about halfway.

[mush145]

Thanks for the information, I will go and check this later. I took a picture of the fusebox and I definitely missing the 43 Relay. Not sure where to get one of thoses.

IMG00053.jpg

[AngeloEvs]

Available on ebay quite cheap or from VW quite dear (£25-00 or so) but numbered 42 now. Same thing, different number looks like a relay but is an electronic module that senses coolant loss and activates the coolant LED so should be fitted really. You can check the regulator at the the vacant socket as it is easier to do. Post piccy later.....

[mush145]

Thanks for all the information on this, finally got to the van today and as luck would have the multimeter had been left on in the draw at home!! Anyway I pulled out the plugs and all seem clean and tidy. I assume when I am looking at the picture the coloured wires that you refer to is related to the PCB board? I have attatched a picture as I have not wires. Once again thanks for all your help on this.

[AngeloEvs]

Using your picture as reference viewed from rear you need to measure across the centre nut and the one to the right of it which is directly fed from the regulator. The centre nut goes to earth and the one on the left tootles off to the thermostat sender. Of course, when your sat in front of the dash and peering down on the nuts then it will be the centre one and the one on its left. You should measure around 10V. You can also test the gauge by short circuiting the centre nut to the other nut.