Gauges not working (MK2)

[Siebrand]

Hello all!

Long time reader, first time poster here.
Never thought I'd see the day that I'd post something on a forum, but might be useful!

Right, so. As the title implies, all of my gauges have stopped working completely.
Except for the fuel gauge, which is always jumping to Full even if it's really not.

I have a little step-by-step plan to troubleshoot this issue.

First up, cleaning the connectors and contacts on the back of the cluster. Already took the entire thing out and removed it from it's plastic shell (kinda looks like an early 80's computer casing haha!)
If that doesn't work, I'll check the fuses again and I'll also check the relays. Not sure which one it is yet, but maybe someone here can show me!

After that, earthing points. Now this is the reason I'm posting here.
Because I have absolutely NO idea where these points are. I've found one on the right side of the engine bay, connected to some blue plastic box?
But that one looks fine to me and I doubt it's connected to the gauge cluster.

Let me know if you know where these earthing points are or if you have any other ideas on this issue!
Thanks!

[David]

Firstly, is your car a Mk1 or Mk2?

My first suspect would be the fuses, I can’t remember which one off the top of my head, so check them all!

Secondly, is the heater blower fan or the indicators working? If it’s a mk2 car, then they’re on the same circuit as the gauges, So if that’s a yes to both, then look somewhere else.

There’s an earth underneath the left front seat, it’d be worth checking anyway, but I don’t think anything behind the dash earths there. From what I remember, there’s another earth behind the dash on the LH side (behind the glovebox on a RHD model), that all the dash wiring goes to, if nothing else works, then find it & have a look. Failing that, there’s another earth underneath the steering wheel shroud which 2 plugs connect into; the interior lights & a few other things earth here, so again, if in doubt, pull it all off & have a look.

Otherwise, check your ignition switch contacts. There are actually 4 circuits in it, one for the ignition, two for accessories & one for the starter. Check to ensure all 4 are working. I can’t remember which way it’s wired, but when the key is in position 2, 7 of the 8 wires should have 12v running through them.

Have a look & let us know what you find.

Hope that helps.

[Siebrand]

So I’ve checked the fuses and they’re all good.
Cleaned up the contacts. Hoping that’ll do the trick.
Can’t seem to find the earthing points at all. Do you have a picture of where they are located?

[Jaba]

Dash earth points are on the steering column support under the shroud somewhere. Not sure where exactly on a LHD car. The other earth point is in the engine bay on the inner wing between the battery and the bulkhead.
You can test by providing an earth direct to the dash. The instruments which have a sensor on the engine are earthed through the sensor to the engine so nothing to check there except for 12v present.
What about the warning lights. Do they come on when you switch on before starting.

[Siebrand]

Yeah, all the lights work just fine.