Tail and brake lights simultaneously gone on one side?

Hi everyone, I'm almost clueless when it comes to electrical stuff so bear with me...
Basically the RH tail and brake lights on my S3 lightweight have gone simultaneously, while the LH are absolutely fine. Now having stared in confusion at the wiring diagram I think I've established that the brake and tail lights are on totally separate circuits, so for them both to be affected but the LH ones be fine I'm hoping it's just that they are close together (ie. some water's got in there or something).
On the lightweight it seems like you access the lights from inside the wheel arch so I was thinking water getting in there is very likely.
I'm sure this is a ridiculously simple problem for most people but as I've said loads of times before I'm completely clueless with electricity. Sorry it's not a more interesting post. Cheers.

Harrris303 said:

Hi everyone, I'm almost clueless when it comes to electrical stuff so bear with me...
Basically the RH tail and brake lights on my S3 lightweight have gone simultaneously, while the LH are absolutely fine. Now having stared in confusion at the wiring diagram I think I've established that the brake and tail lights are on totally separate circuits, so for them both to be affected but the LH ones be fine I'm hoping it's just that they are close together (ie. some water's got in there or something).
On the lightweight it seems like you access the lights from inside the wheel arch so I was thinking water getting in there is very likely.
I'm sure this is a ridiculously simple problem for most people but as I've said loads of times before I'm completely clueless with electricity. Sorry it's not a more interesting post. Cheers.

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Posts are always improved wiv piccies

Probably water or an earthing fault anyway. Good luck

Haha I could easily post some pretty exciting pics of my lights not working! Anyway just wanted someone to tell me I was probably on the right track. I'll get my hands dirty this evening and see if I don't fry myself! Cheers.

I have a 1998 Defender rather than a Series 3, but for me LHS and RHS rear lights are separate fuses, so possibly worth a look / replacement fuse.

cadillacjukebox said:

I have a 1998 Defender rather than a Series 3, but for me LHS and RHS rear lights are separate fuses, so possibly worth a look / replacement fuse.

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Yes but no but..

Left and right tail lights may well be separate fuses

BUT tail and brake are separate fuses too, so to both go out on one side rules out fuse for me

As said above, have a look at the grounding of the lights. Odds are that that would be the central point of failure to take out one side but not the other.

If you remove the back tin cover over the lights on the inside of the box, you can then trace down the wires tied to the box/chassis under a screw. odds are this connection is rusty/corroded/loose/otherwise not making good contact and needs to be dealt with appropriately.

As it is the brake and tail both this could also be a corroded bulb socket causing grief - not an unknown occurrence. Might be worth getting the rear lens off on the appropriate side and using a wirebrush (with power off, of course) to clean up the socket and the outer shell of the bulb.

ajr

Hi - maybe this is too basic; but are you sure the bulb is in properly? When I bought my series 3 I found that on one side the wiring was the wrong way round so that tail lights lit up the brake element and vice versa so the PO had simply put the bulb in the wrong way round. So the bayonets were not in their slots and it just held in by friction and within a few miles had vibrated out a bit - enough so that it didn't light up.

Just a possibility you are suffering something similar.

regards, Justin

7Oaks said:

Hi - maybe this is too basic; but are you sure the bulb is in properly? When I bought my series 3 I found that on one side the wiring was the wrong way round so that tail lights lit up the brake element and vice versa so the PO had simply put the bulb in the wrong way round. So the bayonets were not in their slots and it just held in by friction and within a few miles had vibrated out a bit - enough so that it didn't light up.

Just a possibility you are suffering something similar.

regards, Justin

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my first thought then was to check the bulb, followed by following the wiring back and looking for any breaks or problems

It's a Lucas electrical system - never assume the bulb is bad if the light is out.

More seriously, the simultaneous failure of both circuits to one socket (on a vehoicle not mentioned as recently purchased) kind of made me think corrosion/grounding rather than a failed bulb.

I have been wrong, though, so may be the gent wot's got the problem got lucky.

aje

my money is the grounding too as said above:
, you will find two ferrule push fit connections to ground on the tub behind light covers, Ali tub corrodes causing bad earth to connector, clean and remake.

Might be daft but have you changed the bulb? Start with the simplest possible solution imho

Cheers for all the contributions everyone. I was expecting to get laughed at for such a basic issue!
I took the cover off and had a look. The earth bit is very corroded so I thought that was it, but then I realised the RH indicator is grounded in the same place as the tail and brake lights, but the indicator still works. This seemed a bit mysterious to me...
The bolt holding the earth bit on is seized up so I'll try grinding it off and polishing up the wire to see if that helps. And I'll try polishing up the bulb fittings too while I'm there.

A new angle is that now I've noticed the LH headlight is suddenly a lot dimmer than the RH. And even weirder the main beam indicator on the dashboard has swapped over so that it goes on when the lights are dipped instead of the other way round!
On top of that I indicated to turn earlier and the fog light indicator on the dash started flashing instead of the turn signal indicator! Help!!!

there is a little multi connector just beside the clutch fluid reservoir in engine bay.
separate it and give it a good blast with cleaner and refit, may do the job.

Dim bulbs are usually grounding issues. check your battery negative strap is on well.
to test run a spare bit of cable from your battery negative terminal and touch it on exposed bodywork near your dodgy lights, this will
identify that you have a bad path to earth.


just something else to try

ps I'm arsehooming you have a negative ground vehicle?

Yeah I assume the same haha. Thanks for that, it all sounds fairly logical and worth trying. I'll have a go later. unfortunately I've had to park the landy a couple of miles away due to the flooding situation!
I see you're in West Norfolk joe27, hope you're not too near the sea. We've had some pretty crazy weather hey!

Harrris303 said:

I see you're in West Norfolk joe27, hope you're not too near the sea. We've had some pretty crazy weather hey!

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Kings Lynn
we had 3ft of water lapping the quayside buildings but the floodgates held,
we had a bridge come away from footings and a bank burst near fishing fleet but not as bad as it could have been.

I was on standby with RoverRescue but not called out.

Yeah I live in Salthouse over near Sheringham and it was pretty hairy. Big waves washing up the garden but luckily our hose is slightly raised up. A lot of people weren't so lucky unfortunately...

(Our house is slightly raised up, not our hose) haha

Just had this today too. Replaced the bulb and the housing was cracked too. Quick bodge job with cardboard to get it through the MOT/TUV and looking for new housing. Mine seems to be working fine.