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Brake warning dash light not working....MOT Failure


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Hi there, I'm new to the forum and own a 1987 90. Its in a bit of a sorry state after spending quite a few years being used an abused but maintained poorly. Unfortunately I don't have lots of time on my hands as I am a new dad and want to spend lots of time with the little chap, but I really want to keep my Landy on the road and have worked my way through a long list of jobs to get it through the MOT. The last thing to sort that's giving me the biggest headache is the brake fluid loss/pressure diff switch warning light on the dash not working. I have had the sensor on the master cylinder out and it seems to be working. It has two black/white wire coming out of one connection on the switch which have continuity with the connection on the dash. And one Purple/white wire coming out of the other connection that goes around to the dash entrances for the wires in the engine bay but isn't attached to anything. This wire has been my starting point but I have no clue where it goes and according to the circuit diagram in the Haynes manual it seems to me that it has been retro fitted as I cant see a purple/white wire connected to the switch. However the wiring diagram in pretty much a mystery to me so I could be reading it wrong.

Has anyone out there had a similar problem or any advice for me to help me get my Landy over this last hurdle and back on the road.

Many thanks to all who have read my thread.

Ol

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Hi, thanks for the replies, unfortunately the light doesn't come on during the start cycle which is part of the MOT failure according to the tester, a few people have said that it doesn't get picked up on the MOT but the tester said that its a new regs thing and that any lights that are supposed to light on ignition should light or its a fail. Its very annoying. I'm wondering if I should go somewhere else for the MOT....

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Low brake fluid warning light isn't tested on an mot. If the light isn't on all the time it won't get picked up.

Jon

It is and it should...if fitted.

The low fluid level light is wired through a level sensor that goes to earth when activated (low fluid level) and as a bulb test, via a check relay.

The check relay earths the circuit, and is powered via the starter relay, so when testing the bulb will only light up whilst the ignition is in the crank position.

So the circuit would be ign' +, warning lamp, level sensor, two wires, one to earth to complete the circuit when the level sensor is at the bottom of travel the other is the test circuit and will go to the check relay, probably terminal 30, and earth via 87 when the relay gets a feed to 86 from the starter relay whilst cranking, 85 is the earth for the check relay.

Simples!

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