Nut on back of fuel gauge

[Dr Firefly]

Right, fuel needle and temp needle still swinging around a lot even though I've now got revs back after replacing SI batteries.

Where's this grounding nut I've heard people mention? I've heard that it can cause the movement of the needle. Could someone post a picture with an arrow on pointing to it? Or just describe whereabouts it is?

Cheers, Ian

[E30Mark]

I don't believe the nut has anything to do with the grounding of the instrument, everyone says it does but the panels I've looked at do not have any sort of grounding around the nut. The nut just stops the gauges moving around on it's mounting pins and therefore getting an intermittent reading on the gauges.

I might be proved wrong!

[Dr Firefly]

I've just spent two hours to tighten up the "grounding nut" - I think I agree with E30Mark here - made absolutely f$%k all difference.

I think the whole SI board might need replacing - already done the batteries. Grrr. Gonna be an expert at taking instrument clusters at this rate.

PS does anyone know what the black and white plugs that come out of the box saying "motronic" on it do? They come off the main bundle of wires that seems to go through to the engine bay. They're not connected to anything, and I'm wondering if they have something to do with the problems I'm having with the engine not idling properly when I take my foot off the accelerator. Or are they just to plug into cruise control or something?

Cheers, Ian