No brake lights when tail lights are on

[Circlotron]

Hi all. First post here. Just picked up my first Commodore yesterday, a 1992 VP 5L Executive. Was a cop car then bought at auction and used as a taxi for a couple of years then the owner just used it as the family car. Has done ~500,000km but the speedo has been replaced. Feels like a helluva car after driving a borrowed 2L Camry for the last 12 months.

Anyhoo... just starting to get some of the bugs out of it.
When the tail lights are off the brake lights seem to work normally
When the tail lights are on the brake light in the back window comes on too and the normal brake lights wont come on when the pedal is pressed.
I am supposing the upper lights are tail and lower are brake.
I read somewhere else that these cars get a bit of corrosion in the light bulb sockets. Does that sound likely here?

[axemurderer101]

id be checking to see if the correct globes are fitted. also check if your front park lights come on with the brake aswell

[Circlotron]

Sounds like this problem/solution --> vp break light issues

[Pickle']

Sounds like this problem/solution --> vp break light issues

does not sound like this at all.. brake lights are working without tail lights if i read correctly in this problem the brake switch is not working meaning the brake lights dont work whatsoever tail lights or no tail lights..

to the op id be checking your globes are correct.. also yeah they do get abit of corrosion pull them off and have a look.. i know in the wagon its only 4 screws.. but i dont think this will be the problem as the lights work when the tail lights are off

[AmmoJammo]

check that the filament in one of the brake lights hasn't melted/broken and shorted out to the tail light filament.

happened in my camry

[Warranty Void]

The looms at the very back corrode, I've done quite a few of these now, so sick of them. This is what i've posted before.
The earth on these looms seems to corrode leading to back-feeding of voltage and bizarre lighting behavior and sometimes odd speedo movement.
You can fix the looms if you are keen and know how to track down the dud connections (caused by corrosion where wire joins metal frame) by testing resistance (continuity) from each pin on the plug to it's end point at the other end of the wire (not just at the end of the wire but at the piece it connects onto) Once you have located the duds mark them then you need to solder the wire onto the metal frame, re-doing the standard connector will not last long. The metal frame will not come out of the plastic holder easily you will need to apply an electric drill to get it out.
Sorting these looms will fix most lighting issues you will ever have on a VN-VP. It's worth sorting out, once you've done one side the next one will take about 15 minutes.
With the looms and plugs out you can also see exactly how the single and double filament bulbs go in and which way around the double filament bulb goes
(hint park light filament is less bright than brake light filament)
You will need a multimeter or a test light and 12 volt battery charger to find the bad connections. I prefer to use a multimeter.
PS you can buy these looms new from Rare Spares for about $30 each.

[Circlotron]

$30 from Rare Spares hey? Sounds like the way to go. I'll let you know how it turns out.

[Hangman]

My VP does this, the bulb holders are corroded/rusty/farked. Pretty common problem.

[Circlotron]

Righto, got it sussed now. The black earth wire that goes up the side of the socket was corroded where it is supposed to make contact with the metal outer part of the socket. Cut the wire, made a thin extension and passed it up the other hole in the socket and soldered it to the aforementioned metal bit. Did lower sockets both sides of car just in case. Maybe I'll do the other globes one day.

Next bit - how to check the lights by yourself. No shop window available to see a reflection in so I took a video of it and watched :-P

[Circlotron]

P.S. thanks heaps guys.

[channingvp]

You can buy single bayonnets from autobahn for like $2 - 4
just replace and rewire them easy and cheap as ( i had the same problem)

[Circlotron]

Hey, thanks for that channingvp. Might go have a look-see when I am feeling a bit less lazy.

Hey, guess what? Now that I fixed that earth problem the windscreen squirter goes much better too! Used to go only ~40% up the windscreen but now it goes right to the very top and I have to adjust the aiming :-)

[Defected]

Go to the wreckers n buy new looms, but sounds like a wrong globe or something, i let a single filament globe sit where a double shouldve been, cost me lots in the long run. Electrical issues suck