rear brake light issues

well just spent the day chasing electrical gremlins on the series i brought home last weekend, got the hazards, indicators working, wipers going, but can,t get no life from the brake lights got power to the brake light switch trace'd the wire back to look for obivous breaks in the wires earths are okay as night time lights all light up so what do u think rewire the bugger with fresh wire just for the brake lights or am i missing another fuse or relay some where

bulbs or switch itself if its one of the hydraulic ones is where I'd start

the switch is passing power on the pedal but its not passing the power down the brake light side of the element both bulbs are okay there is another switch on the brake servo but i presume thats for low fluid level warning or if not i,ll check power on that over the weekend but thanks for the input Doc (as always you come u come to the rescue with things i had'nt thought off)

low fluid warning on a series ????


that'd be a first!

thanks i,ll check that switch out then

Dr_evil said:

low fluid warning on a series ????


that'd be a first!

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Brake warning lights were fitted to some S3s but they monitored servo, brake fluid pressures and excess pedal travel. It's in the book at the start of the braking section. Don't think they did fluid level, though.

switched are often faulty. I've gone through 3 in a few months (genuine Lucas too) . the pin contact point varied and no matter how I adjusted it I couldn't get it to work. issue was that it would switch on but then the pin needed to come back out even further to switch off. if its the switch, try ang get new old stock Lucas as much better quality

disco924 said:

the switch is passing power on the pedal but its not passing the power down the brake light side of the element both bulbs are okay there is another switch on the brake servo but i presume thats for low fluid level warning or if not i,ll check power on that over the weekend but thanks for the input Doc (as always you come u come to the rescue with things i had'nt thought off)

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The switch on the servo is for the brake lights, if there's one on top of the reservior, that's for the low fluid warning. If the switch is passing current when you press the pedal, then the fault must be in the wiring back to the lights. I'd find the brake light wire where it comes out of the chassis wiring loom (usually drivers side rear corner of the tub) If there's no juice there, then I'd run a new wire. You can just run it externally first to prove where the fault is. Having said that, the usual culprit is the earth connection at the rear, worth checking the one for the brake lights, they can corrode and fail individually. Again, you might run a new one to check the circuit.

When you describe the switch as being "on the servo" is it actually on the servo front faceplate or is it on the pedal bracket behind the servo? One is a vacuum failure warning switch and the other is the brake light switch.

Dr_evil said:

low fluid warning on a series ????


that'd be a first!

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There is a low fluid warning! If you dont stop you've got low fluid

Can I ask what your using to check for "power"? If using a multimeter it can show voltage but that is with no load attached. Think of your battery it can show 12v with meter but fails to turn starter motor. Reason is that as soon as any load is placed on circuit voltage drops.
Best to check circuits with simple test lamp. you can make one solder two leads onto an old indicator bulb connect one to earth and then look to see where you loose power.

to check power i,m using the old fashion brass pin probe that lights up so its the same as using an old bulb trick answer the other questions earths are fine the other side of the bulb element lights up. but its been a bit wet today so i only manage to flush the radiator fitted new water pump and belt, so i,m going to check the rest of the loom out now as i see some one in the past has had ago at the wireing as there,s a bloody big block connector mounted to the bottom of bulk head just below the clutch master cyclinder wide open to the elements and muck but thanks for all your input will be slogging a way at it

that big block plug is probably factory fitted. I believe they are all like it Sir!

well if it is i,ve found another 2 in the arse end today linking the trailer plugs up. drivers side high mounted one running from drivers rear lights, and the tow ball trailer socket running from the passenger side rear lights, counting the one in the front plus the 2 plastc block connectors running the front lights thats 5 all together disconnected the trailer plugs got my brake lights back (yippee!)

oxides said:

When you describe the switch as being "on the servo" is it actually on the servo front faceplate or is it on the pedal bracket behind the servo? One is a vacuum failure warning switch and the other is the brake light switch.

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I mean on the pedal box - apologies for any confusion. Part 589223.

disco924 said:

well if it is i,ve found another 2 in the arse end today linking the trailer plugs up. drivers side high mounted one running from drivers rear lights, and the tow ball trailer socket running from the passenger side rear lights, counting the one in the front plus the 2 plastc block connectors running the front lights thats 5 all together disconnected the trailer plugs got my brake lights back (yippee!)

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A good fix - probably a false earth on the trailer wiring. :clap2: