K12 - Rear Brake Light Not Working, Bulb OK?

[a18041967]

Rear near side brake light has stopped working and I initially thought, ahh easy just change the bulb, the bulb is OK. The off side and centre brake lights are OK, indicators, and fog lights also OK.

Using a multi meter I've checked the bulb and its OK, I've checked the bulb connectors and there's no 12volts.

Is there any suggestions as to what I should check next, my thoughts:

• I'm assuming there's only one fuse for the brake lights, therefore this is OK as other two brake lights are working?
• Are the brake light daisy chained together, eg off side connects to Centre and centre connects to near side or do they connect to a single common location? Originally the centre brake light didn't work and this was due to poor connections between connector and build, if daisy chained could this possibly be the cause?
• Is there a diagram that shows how the cabling is routed inside the vehicle?

The only thing that has changed recently on the car is an issue with the boot electric opening switch, I'm also assuming these are not linked in any way? My solution to this was to replace the boot switch with a new switch located inside the car near the drivers compartment. I ran a two core wire from boot to the front of car, disconnect switch in boot and replaced with internal switch, appears to be working OK.

 

[MattInARedMicra]

If you swap the bulbs left to right the same issue? the working bulb into the nonworking side, Just to rule out having bought a broken bulb

and just to confirm you're taking a reading at the bulb holder with the brake peddle pressed in? fog lights don't always light both sides

any melting of any plastic parts?

I'll try to find a diagram in Haynes for you, but hopefully someone has it to hand sooner than that because I don't know where I've put it. Typically the loom to the back runs under the carpets on one side of the car, and the lights should all be independently run from the engine bay along this loom. However, some cars have features where if one light fails another one comes on to replace it until it's fixed so in that case there must be some sort of crossing over, I'm not certain how it works

It could be a ground fault on the broken side. If the bulb isn't earthing or returning to the neg side it won't light up, and sometimes the connector can short around the bulb due to rusting or corrosion. This could be what stopped your boot switch from working. It could be a broken/frayed wire somewhere which will be difficult to track down but you'd have to check for continuity along the length of it in that case. It's worth checking the fuses for continuity anyway, there could be separate fuses/relays which will be written on the back of the cover

 

[Mika The Finn]

G'day from the Land of the Finns!
I had same problem right turn signal, cause was missing/broken ground.
I fixed it by adding ground wire from 'circuit board's ground to under rear light assembly attachment bolt.
This took about 15min to do.

 

[a18041967]

G'day from the Land of the Finns!
I had same problem right turn signal, cause was missing/broken ground.
I fixed it by adding ground wire from 'circuit board's ground to under rear light assembly attachment bolt.
This took about 15min to do.

Would it be possible to provide any further details regarding the grounding and the exact location. The reason for asking is I seem to remember that all the bulbs within the rear light cluster share the same ground and based on the fact that the other lights are working I'm struggling to understand where I should look?

 

[Mika The Finn]

Check galvanized 'wires' with multimeter, ground path might be disconnected/broken.
I found my missing ground connection with multimeter. Near side, was it right or left side?
I'm still wondering why you island people can't simply use plain left or right?

 

[a18041967]

Update, after checking all the cabling etc I decided to swap the working brake light with the failed one, magically it worked so clearly a failed bulb, and yes I should have done this first, lesson learnt.

What caught me out was that I'd checked the bulb using a test meter and hadn't realised the bulb was brake and light, I tested he light which was working but brake light had failed but not tested.

So thanks for your help and suggestions and I'm now a little wiser than when I started.