GQ Brake Lights

[Corsta0211]

Hey Everyone. I bought a new brake light assembly for the GQ in January and it has worked fine, however recently whenever I have the headlights on, the left rear brake light stays on. When I tap the brakes, the left brake light does nothing, it just stays lit. When the lights aren't on, both brake lights are fine. Obviously this needs to be fixed, I don't need attention from the cops. Help will be appreciated. It's a 1989 TD42. Thanks, Corey.

[Turtle_au]

Is the light a combined park/brake globe. Then check earth for left light. Park light is earthing through brake light.

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[Corsta0211]

Hey Mate. You wouldn't happen to know where the earth ends up would you? It's a combined globe, yes.

[GQtdauto]

Check the bulb itself for corrosion .

[Corsta0211]

Thanks mate, there's none it's a brand new assembly and bulbs.

[garett]

is the globe in the right way ? eg i've seen the wires backward so you get brake all the time with parkers. cheap Chinese stuff

[GQtdauto]

is the globe in the right way ? eg i've seen the wires backward so you get brake all the time with parkers. cheap Chinese stuff

You may be onto something because it's a new assembly the fault should be in the assembly.

[Corsta0211]

Thanks for that, I'll check that tomorrow when I have some light. Would that be the plug?

[garett]

could be wired wrong it could be just a backwards globe. if its wireing you can pop out the connecting bit with a pick or pointy object and swap for the correct one. test light is your friend

[dom14]

Hey Everyone. I bought a new brake light assembly for the GQ in January and it has worked fine, however recently whenever I have the headlights on, the left rear brake light stays on. When I tap the brakes, the left brake light does nothing, it just stays lit. When the lights aren't on, both brake lights are fine. Obviously this needs to be fixed, I don't need attention from the cops. Help will be appreciated. It's a 1989 TD42. Thanks, Corey.

Most likely it's the globe. GQ brake light globe is a dual filament one. One for parking & one for brakes.
When a one end of a filament ends up fusing with the other due to a factory fault of the globe, above bizarre behaviour can be the result.

Swap the globe and I would say that will fix the problem.

One thing you can do to confirm or rule out it's the globe is to swap the brake light globes from the faulty side to the other side and see if the problem moves to the other side. If it does, then it's definitely the globe.

[Corsta0211]

I tried swapping the globes and that didn't fix it. The plug is in the right way. I'm starting to get worried it's going to get expensive with an auto electrician having to look at it...

[GQtdauto]

Ok so you've ruled out the globe , have you rechecked the wiring going back along the wires as far as you can ? Also check your trailer plug if you have one .
Because it's only one side makes me think the problem is at the back somewhere .

[GQtdauto]

Is the light a combined park/brake globe. Then check earth for left light. Park light is earthing through brake light.

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Also check what turtle has suggested .

[Turtle_au]

Also check what turtle has suggested .
Is there a seperate earth wire from the globe holder or does it use the housing.
Reminds me of years ago I fitted a bikini fairing to my bike, spent an hour trying to get indicators to work and I'm an electrician.. Then fitter mate asked "Is fibreglass a good earth?"

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[mudnut]

I once bought a brand new fuel gauge sender and it was wired to go from full to half back to full. So I suggest that you recheck that the circuit on the new unit.

Also as a last resort try using your old globes, because the new ones might be made wrongly made.

Both circuits use the one earth (the metal body of the globe), it should go to the wire on the connector.

[Corsta0211]

Also check your trailer plug if you have one .
Because it's only one side makes me think the problem is at the back somewhere .

Actually you might be on to something... It started around about when I used my mates trailer. I have a 7 pin flat on the back, and I used a adaptor for his 7 pin round trailer plug. What can I check on the trailer plug to rule that out? It's ground has a wire I do believe, I cant see one on the assembly.

[GQtdauto]

You need to check that when you put the trailer plug in and pulled it out you haven't damaged it in someway or there's not a pin broken off from the plug inside .
I would pull the plug apart and check the wires and how the brass ferrules are seated , make sure the left hand tail light wire is not touching another wire .
You may even try disconnecting the left tail light and brake light from the plug and see if the problem still exists , if not that's where your problem will be .

[Turtle_au]

Have you put a meter onto the contacts in the base to see if there is power on both or only 1 contact when the parkers are on. Is there a short between the 2 contacts or could the contact base have moved around when changing bulbs.

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[dom14]

I tried swapping the globes and that didn't fix it. The plug is in the right way. I'm starting to get worried it's going to get expensive with an auto electrician having to look at it...

It was worth a try. :)

I don't think auto sparky would charge a fortune to find that problem, 'cos they are usually trained to find these kinda issues quickly or bypass the problem quickly.
As the experienced guys here suggested, trailer plug connections, earth connections, short circuits, etc at the back of the park/brake light globe might be the culprit.
Arm yourself with a multmeter and keep at it.