Thread: Driver's side brake light.

If the other stop lights work, the pedal switch is fine, try running a separate earth to the globe.

IIRC, the trailer light plug is also on the drivers side. Does the trailer brake switch work or not ... assuming you have trailer plug.

Won't be brake pedal switch, as you have power to the plug/wire and LHS lights up(?)

If it's the earth(brown wire), and your RHS indicator is working, there is a joint about 5cm from the fixed plug on the back of the unit. The brown wire goes from the plug to the joint, then one brown wire to indicator and longer brown wire to light bulb holder.
Check that joint.

Also note that the earth is common to the tail light too. The side body of the bulb is the earth.

So if tail light works, but brake not, then either the brake light power wire to the bulb holder is dodgy, the power pin for the brake light is bent down and not contacting the bulb, or the bulb is fitted askew somehow.
If earth is open circuit, then the tail light shouldn't work either.

Update, I have voltage at the connector! 13.84 V and varying. I have voltage in the bulb socket for both globe pins. There is almost zero resistance on either conductor or the earth, from the plug to the socket, about 20 cm? the meter sys 0.5 or 0.4 none of the globes I have tried are open circuit between the pin and the earth I have tried 3! everything check out.
I have the work experience kid out there pushing on the brake pedal and I get voltage, 13 V and change. Same voltage on the rear lights (side/parking lights?) the rear lights work on both sides!!
The other brake lights work!

Maybe if Option B fixes the Three Amigos, the brake light will work.

Inside the bulb holder, the two flat pins that the bulb pins sit on ... do they have voltage?
So tail works? then earth is good.

Inside the bulb holder I can't remember which flat pin is tail and which is brake, but if that part is not getting power, but power is going to the bulb holder(rear), then most likely a break in the rearside pin where the wire is connected/crimped/soldered to the flat pin inside the bulb holder ... or the flat pin is bent down just enough that the bulb isn't connecting there.

If the wire to flat pin connection is dodgy, try pushing the wire further inwards to see if that will get brake light power to the flat pin.

Originally Posted by AK83

Inside the bulb holder, the two flat pins that the bulb pins sit on ... do they have voltage?

Yes, that is what is driving me nuts. I've even sanded the flat bits to remove any corrosion, no change.

yes it is two steps forward and one step back. I'll do option B tomorrow, hopefully I'll achieve something!

Originally Posted by AK83

Inside the bulb holder I can't remember which flat pin is tail and which is brake, but if that part is not getting power, but power is going to the bulb holder(rear), then most likely a break in the rearside pin where the wire is connected/crimped/soldered to the flat pin inside the bulb holder ... or the flat pin is bent down just enough that the bulb isn't connecting there.


If the wire to flat pin connection is dodgy, try pushing the wire further inwards to see if that will get brake light power to the flat pin.

The flat bits are getting power.

Almost certainly there's a dodgy wire there.
I assume you test power with a multi meter. So you see voltage at the seat of the bulb contact, but as soon as you put a bulb in, no power.

The brake bulb is a higher load (21W) the multimeter no real load.

Try spin the bulb the wrong way. ie. use the tail filament in the brake slot instead. tail lamp is 5w, lower load. It'll probably still be too much ... but interesting to test.

I'd say you'll need to check the two wires from the lower plug and the brown wire at the junction ..... to the bulb plug. Something there at the pins isn't right.

Note tho this is assuming that you have towbar and electrics and all is well down there. Down inside the pillar could be a large-ish connector that give power to the RH light unit and the trailer plug.

I'd check the trailer plug for brake power too(not multimeter tho).
Remember that, if you see voltage on the wire via a multimeter, but still get no light, then there is an issue getting current to that line.
If you can confirm that the trailer plug is getting power to a load, then this eliminates the trailer loom connector(that one down the inside of the pillar) as a culprit.

On my D2a, I had a headscratching issues with that trailer loom connector.

If you don't have a bulb/wire .. or test light to test with .. you could even try to temporarily connect the LHS light unit to the RHS and see if the brake light works.
Thinking is: if the problem is the light unit(or bulb holder) then the LHS which works ... will work. If the LHS one doesn't work, then your power issue is further down the line(ie. suspect the trailer loom connector)

Originally Posted by AK83

If you don't have a bulb/wire .. or test light to test with .. you could even try to temporarily connect the LHS light unit to the RHS and see if the brake light works.
Thinking is: if the problem is the light unit(or bulb holder) then the LHS which works ... will work. If the LHS one doesn't work, then your power issue is further down the line(ie. suspect the trailer loom connector)

A brilliant idea!