Low fuel light nightmare

Right lads and lasses I'm hoping somebody can help me out with this because it's doing my head right in... iv started having problems with my low fuel warning lamp coming on randomly or staying on or fading bright and dim as I'm driving along (it's on a 1992 200tdi defender). Iv been trying to trawl the internet to see if anybody's had a similar problem and how they sorted it but with no success. So far iv:

tested the sender and it appears ok (no dead spots on variable resistor)

cleaned the earth on the bulkhead by the fuel filter and even added an extra one from the sender to the fuel tank

confirmed continuity between the green/black sender wire to the gauge and the low fuel pcb

tried earthing the green/black wire, the gauge reads full range but the lamp stays on

iv had the sender out the tank and moved it through its range manually, the gauge appears to work as it should but the light stops on

confirmed the continuity to earth for the gauges and the low fuel pcb

confirmed +12v to the gauges and the pcb

Is there a relay in the circuit to bring the light on that could have welded in or are there some more hidden earth points behind the dash anywhere? Iv been looking thru the wiring diagrams in the Haynes book of lies and the lr workshop manual with no luck at all. it seems everything is pointing at the little pcb in the loom being fried however I can't seem to get hold of a spare to swap and check it. Any help would be massively appreciated as it's got my head battered

Hi

If you disconnect the sender wire at the tank do you still get the light glowing?

Cheers

Yes mate it stays on with either sender wire disconnected

Watching, I have the same issue but just put it down to the fuel swishing about in the tank... it would seem, this is not the case.

I have the same issue - done all the tests above and have, as yet, not found the root cause.

So am watching too, and hopefully be able to trace the issue..... I am currently thinking electrical tracking on the binnacle light board.

But my main task at present is finding out why the fog lamp comes on with the Reverse Lamp.....FL comes on perfectly on its own with switch, without the RL illuminating....but if the FL is switched on and you put it in reverse, the RL doesn't light up until you turn the FL off.....

All lamp holders and wiring are new....so I am stuck on this one too....

When mine was working it would get to a point where it would flash as I went round corners and over bumps etc but that was because I was actually low on fuel lol but it's just started doing what it wants now even on a full tank

Saint.V8 said:

I have the same issue - done all the tests above and have, as yet, not found the root cause.

So am watching too, and hopefully be able to trace the issue..... I am currently thinking electrical tracking on the binnacle light board.

But my main task at present is finding out why the fog lamp comes on with the Reverse Lamp.....FL comes on perfectly on its own with switch, without the RL illuminating....but if the FL is switched on and you put it in reverse, the RL doesn't light up until you turn the FL off.....

All lamp holders and wiring are new....so I am stuck on this one too....

Click to expand...

Do you mean the tracks on the warning cluster mate or the little comparator pcb taped up in the gauge loom? Sounds like your having even more of a mare. I hate random electrical faults me lol

Ive never seen a low fuel light on my 1993 90, always assumed it didnt have one?

I ended up taking the bulb out of mine. I never did get to the bottom of it!

bluedog333 said:

I ended up taking the bulb out of mine. I never did get to the bottom of it!

Click to expand...

I have to say I am rapidly coming to that conclusion myself.

At least I'm not the only one then haha hopefully be able to take my loom into work and have my mate give the pcb a looking over as he used to repair hospital equipment at component level lol. if I can definitely prove the board is knackered il be happy converting to a 3 wire set up but I'd rather know for sure rather than the light being on because something in the loom is shorting out. Will update with what we find...

I have the same problem on my TD5 Defender. Fill up and light goes out. 75 ish miles later light comes on and stays on. Also fuel gauge randomly shows full, even when near empty. Checked wiring and manually operated fuel float and all works fine except the fuel lamp stays on unless float arm moved to full position. refit pump and float and back to playing silly buggers. Been like it for over six years and drives me nuts. Wasted hours on this and still none the wiser.

Well after much faffing iv finally sorted it. As I suspected the chip on the board was knackered but I managed to find a website that makes replacement modules. I noticed that they also sold a module to match my 0-180 ohm VDO fuel gauge with the landys sender so I ordered one, fitted it and now problem solved! Would definitely recommend this bit of kit as it's let me use the fuel gauge I wanted and sorted the warning light fault. The website was www.spiyda.com if anybody wants one

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The knackered board

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The new module

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Wired in

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All fitted

Looking for an assist here... my fuel gauge didnt work since buying the car. Im tracing every wire point to point and found the 3-wire loom from the tank sender broken and disconnected.
I have since repaired the broken wire, and hooked up the tank side.
I have the black going to a ground ring terminal at the bulkhead.
I have the green/black stripe wire going to the back of the fuel gauge via a harness in the engine bay.
I dont know where the white/slate wire from the tank sender goes to.
I found the low fuel level unit all taped up- traced the White/Slate from the processor board to the warning light cluster ok.
Cant figure out where the White/Slate from the tank sender goes.
Any help would save a headache.
Thanks