Morning all, took car for MOT last week and all 13 bulbs had blown in the 3rd brake light . . . £2.50 per bulb x 13 =£32.50 so decided to buy another lamp unit from Halfords to get the car back legal again ( cheapest option ). . .

did this no problem, but had to wire into my loom, which annoyed me a bit having to splice wires etc, due to the connection for original lamp being 'dead' - no power coming through when new lamp wired into it . . .

The new lamp also hangs down off the window and doesnt sit in the proper area for the light - another slight annoyance.

I am lead to believe some MK1 octavias had an LED 3rd brake light, and if so which year / models and would it be a case of plug and play into a vehicle that didnt have LED unit to begin?

Moving on, The rear de mist appears to have stopped working, the light is on when you press the switch but rear screen stays misted up. The fuse is not broken, so where would I be best to start investigations into the cause - dont really want to start ripping off bits of car Un-necessarily.

Many Thanks

Rob.

Know when you say there's no power to the original brake light? Did you trace the wire to look for a break? Sounds wrong that all the bulbs have gone and there's no power? Also with the rear heated window don't you think there might be a connection between the problems?

Check the wiring between the boot lid and body of the car think it goes though a rubber hose thing at the top of the window

Snap, I am thinking a common electrical fault applies to both the 3rd brake light and the demister. I would start by checking the earthing was good.

I did think there might be a link between the two, there has always been a few bulbs out on the light, and the rear de mist hasnt worked for a while, but thought nothing of it.

will check the wires later on between boot lid. I assume there will be a ground point for the part of the loom which has the rear screen and lights in it?

Wouldnt have anything to do with me installing tow-bar wiring do you think?? It was a purpose made kit so plug and play . . just seems all too co-incidental

Rob.

Could be m8, use a multi meter and try and see first if there is any power, if there isn't try and check the join between the tail gate, see if there are any broken wires. If there is check the earth for the same.

I'm not 100% clued up with where the tow bar wiring and the hatch wiring goes and if they are close to each other. Worth checking around tho

ok no problem, I was going to use a multi meter but I dont have the foggiest how to use it . .. all the options on the dial :S

I installed the tow bar wiring myself, and only really touched the rear light cluster connections . . . But i dare say I had something to do with it.

Will report back findings with pictures if necessary. The plan is to put LED strip inside the 3rd brake housing provided I can get the wiring working again.

Rob.

Where did you get your tow bar wiring from? I'm hoping to get a tow bar soon, sorry to change the subject

I would start by unplugging the new towbar wiring and see if that brings back the demister / new 3rd brake light.

Stick the meter on 12vdc (or the next setting above, maybe 20 or 50vdc). Hold the black probe against a metal earthing point near to to the rear light clusters and then check the +12v feeds to the brake lights and demister. if you get meter movement that suggest the +12v feeds are ok, so them move the black probe to the -ve of the brake light and the demister and see if you still get a reading. A lack of a reading would suggest an earthing fault.

note: the demister will only work with the engine running.

bought from Tow Quippe -(spelling may vary) Got a Westfallia Detachable and the car specific wiring kit. . . but what they DONT tell you is the kit is for an estate. . . so for a hatch you have to modify the wiring kit a bit . . .easy enough to do. I leave mine on all the time to stop tailgaters! they soon back off when they see it. though the rear bumper has to be cut underneath a fair bit to accomodate and the wiring plug will not fold away unless more slicing and dicing is done . . .

Will post up pics in guide section when ive got time, or drop me a PM and will be happy to help with any probs / give advice.

Rob.

I have a Tow Quippe (sp!) fixed bar on my estate, I got it from ebay. I had to crimp the cables into loom manually though.

just re-posting in this topic i started the other day . . . .

. . . checked the fuse again for rear de mist and its fine, also fitted a spare dash switch i had. the orange light comes on in the switch but no de-misting happens . . . also stuck the multi meter in the 3rd brake light socket, and nothing coming through.

anyone else got any ideas before i have to remove half the interior to try and trace the fault(s)?

any help on this greatly appreciated.

Rob.

Where are you based? Roughly.....

few miles outside Worcester. have you had these problems too?

Rob.

No, but it sounds like you need a hand sorting it. If you were a bit nearer to me I'd offer to help out. Maybe someone in your area can help?

This might sound a bit random, but does your rear window washer work?

the rear wash wipe works, i am going to check the earthing point again later but not holding out much hope .. . although the two breaking seemingly together is a bit strange . . .

thought id cracked it with a new switch yesterday but the problem is obviously further down the line than the switch.

I was wondering if the pipe to the rear wash had popped off, and leaking water corroded a multiplug with those wires in it.

ah right, nah thats working well. i am going to have a poke around see if the earthing point is ok for the circuits they are on. . . on the side note, rear door, drivers side doesnt open either lol!! but thats been happening for ages. best left until after winter i think. . .

If you pull the cover off the inside of the boot, on the nearside, all of the connectors are there. You should be able to trace out which one or ones are for the brake light and demister. If nothing else, stick the meter in there to see if you've got 12V at that point where the cable goes up to the top of the tailgate. If you have, then it looks like it might be a broken wire or two in between the tailgate and the body.

right . . .have had a poke about tonight . . fuses all intact. . wiring seems to be intact inside the boot lid and the earth points both sides behind rear lights seem solid.

broke open the haynes book and studied the wiring diagrams. . page 12.29 . . on the heated rear screen bit at bottom. . . i had a look on the battery top at the fuses ( 3x green 30amp ones ) on top of battery and they seem ok. I was unable to locate the "relay plate" (fig 6 in haynes) as i reckon this may hold the answer??

how to do i find this plate, is it underneath the battery?

Also, could somebody point me in the direction of the earthing point E6 "behind dash pannel" as the book describes, as this could be anywhere, and it is one of the earthing points that the screen goes to. the other is E5 "luggage cmptmnt" which ive already checked.

Any further tips / advice welcome . .. loosing rag with it now.

3rd brake light i reckon has a break in the wiring ** SOMEWHERE** but as ive bodged in a replacement for now im not too bothered. its just the rear demist i need, very useful in the snow and ice (very quick too from what i remember)

thanks again

Rob