Instrument lights

For all those wiring gremlins we love, this is the place to discuss them.

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alangs1200
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Instrument lights

Post by alangs1200 »

For no apparent reason at all my instrument lights are no longer working on my 89 SA.

I've checked (& changed for good measure) the fuse - 4A in slot 9 - to no avail. And I've also checked the rheostat is turned up. Is this a circuit where a single bulb failure causes the entire circuit to fail (a bit like dreaded christmas tree lights)?. Or does anyone have any other suggestions for where I start to look?

Thanks.
1993 - parted with an Excel Celebration to make way for kids. 2020 - parted with the kids to make way for an Excel SA.

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rbgosling
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Re: Instrument lights

Post by rbgosling »

Without checking to be sure, I'd be most surprised if a single light failure would put out the lot.

My first suspect would still be the dimmer. Check that you've got voltage there, then try by-passing it.

If that's not the problem, the next suspect would be a bad earth, as they all no doubt share the same earth.
"Farmer" Richard

1990 Lotus Excel SE (Lilith)
2004 Jaguar X-Type Estate

Zag
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Re: Instrument lights

Post by Zag »

Single bulb will not cause total failure. As above I would suspect the dimmer and bypass by adding a jumper cable between the contacts. This sorted mine out.

Pete Boole
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Re: Instrument lights

Post by Pete Boole »

I'll also suggest the rheostat - they're really flakey. I always bin them.

Pete

alangs1200
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Re: Instrument lights

Post by alangs1200 »

Thanks all. Looks like I'll be bypassing the rheostat for something to do tomorrow!
1993 - parted with an Excel Celebration to make way for kids. 2020 - parted with the kids to make way for an Excel SA.

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DavidOliver
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Re: Instrument lights

Post by DavidOliver »

To get to the dimmer you need to get to behind the main dash panel.
There is a post on this showing where the two wing nuts are.
Briefly for a non SE car; Gearlever knob off and remove leather cover.
Radio out, normally with a couple of flat steel prongs to release the side clips.
Remove the two air directors, they are held in Top and Bottom by steel flaps
which need to be pressed against the director body. Top one is a b·····d to get to.
The heat and fan switches have a very small release button on one side you need to depress
while pulling off the knobs.
You can now release the two wing nuts.
The fascia panel is released by displacing the lower edge until you can free vertically the top edge.

I have recently replaced the instrument bulbs with green coloured Leds, a great improvement.


Dave the cog.

alangs1200
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Re: Instrument lights

Post by alangs1200 »

So thanks for the tips. After extensive dismantling of the trim I eventually got to the back of the rheostat. It turns out that the rheostat itself had pulled apart. I suspect this happened when I installed a new head unit a couple of months ago. As I’d not used the car in low light I’d simply not noticed until now. Once reassembled all was good and I reinstalled the rheostat at about a 30 degree angle to make sure nothing could be fouled by the head unit on reinstallation. All is good! Now I just need to turn my attention to fixing the horn and rear fog lights. Faulty relays suspected in both cases as the fuses are good and so are the bulbs! Thanks again.
1993 - parted with an Excel Celebration to make way for kids. 2020 - parted with the kids to make way for an Excel SA.

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