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dra890

Dashboard electrical problem

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I have an annoying intermittent problem with my series 3’s dashboard. When I have my lights on (sidelight, headlight, main beam, it doesn’t matter) the dash lights frequently dim and flicker and the indicator repeater lights on the dash do the same.  In addition both the temperature gauge and the fuel gauge will read too high while this is happening. If I happen to be indicating while this is happening then the dashboard indicator repeater that should be flashing will remain dimly lit and not flash, but will sometimes pulse, and the opposite repeater can pulse with it.

None of the external lights are affected at all by any of this. 

 

I’ve checked all the front and rear sidelight bulb contacts, connected the front sidelight earth wires directly (via a connection block) to the battery earth, taped the wires behind the dash from the dash light switch to the bulbs with insulating tape, cleaned both dashboard bezel earth connections, cleaned the bulkhead earth terminal, and run a lead directly from this terminal to the battery earth. None of this seems to have made a difference. 

 

Any suggestions?

Dan

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Ummmm. You've done the usual things I'd do.

I think you need to look deeper.

You do have a multi meter? I'd be checking voltages in the bulb holders, resistance across lots of things, possibly corrosion between bits of individual components, or contact points in bulb holders.

Ummmm.

I want to think about this, with a wiring diagram in front of me. 

I think earths, still, but I've a niggle about the gauges in my head. Over reading is not enough volts, isn't it?

 

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Actually over reading is too many volts. That’s the thing that’s been puzzling me most about this. It suggests the voltage stabiliser either has a bad earth, or voltage reaching its earth (when the lights are on) and this is stopping it switching to reduce the voltage to the gauges. But the stabiliser shares its earth with the gauges, so this effect should cancel out. I’m wondering if I just have an earth problem on the left hand bezel where the stabiliser is, but the right bezel which houses the gauges is okay. But then would this cause the dash light problems I’m seeing which effects both bezels and the indicator repeaters equally?

Confusing!

 

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Just to round this up, since the wire connecting the bulkhead post to the battery didn’t have any effect I disconnected it from the battery, fed it through the bulkhead and jury-rigged it into the auxiliary lamp earth to test out my idea. Ran it for a couple of days like this without the fault occurring. I also noticed that the dash was a little brighter like this. Then I unplugged it and the problem returned. So a length of 5 amp cable and a couple of ring connectors to replace the earth lead from the left hand bezel to the bulkhead earth post and my problem’s solved. 

 

Dan

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It's your dash earths, almost certainly the connection to the bulkhead, and probably due to rust.  Have a look for a bolt with a few black leads on the top of the foot well, next to the clutch pedal box.  Give the terminals a good clean up, make sure the bolt hole has a clean band of steel around it and fit a new bolt, all copiously smeared in Vaseline to keep it rust free.

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