Car light issue.

[Salty seadog]

Changed a brake light the other day, (nearside as you ask) just been told that my brake lights are stuck on.
A little bit of experimenting gave these results.

Sidelights or headlights on = brake lights stay on.

Sidelights and headlights off = normal brake light function...... However when I press the brake pedal the sidelights come on until I release the brake pedal.

Thoughts on the cause sought thanks.

 

[deptfordmarmoset]

Changed a brake light the other day, (nearside as you ask) just been told that my brake lights are stuck on.
A little bit of experimenting gave these results.

Sidelights or headlights on = brake lights stay on.

Sidelights and headlights off = normal brake light function...... However when I press the brake pedal the sidelights come on until I release the brake pedal.

Thoughts on the cause sought thanks.

When that happened to an old car of mine it was caused by a faulty fuse.

 

[CXRAndy]

most common issues are generally bad ground connection. You then get back flow current through lamps giving odd lighting situations.

Check each lamp earth point or provide a known good earth to each lamp to locate the fault

 

[gbb]

Agree with CXR Andy, first places to check IME.
Rustly, corroded lampholders, loose wiring, bad earth. A close and detailed visual examination is needed, not just a glance.

 

[Drago]

Dodgy ground connection seems likely. Brake light switch perhaps?

 

[fossyant]

Bad earth. Get out the electrical contact cleaner, or if stuck, brake cleaner. Spray the bulb holders and any circuits.

 

[twentysix by twentyfive]

What did you move around when you did the repair? That's the place I'd start.

 

[Salty seadog]

What did you move around when you did the repair? That's the place I'd start.

Just removed the rear light cluster. It is a squeeze to get out.

 

[twentysix by twentyfive]

Just removed the rear light cluster. It is a squeeze to get out.

Might have accidentally disturbed something?? Like the earth as suggested above?

 

[neil_merseyside]

Dual filament offset pin bulb put in the wrong way round always played havoc with trailer circuits as it mixed up the earth paths or somesuch, might be the same on a car, though I'd hope a car light unit wouldn't allow the misfitting.

 

[DRM]

Dual filament offset pin bulb put in the wrong way round always played havoc with trailer circuits as it mixed up the earth paths or somesuch, might be the same on a car, though I'd hope a car light unit wouldn't allow the misfitting.

This, you need to remove the bulbs and turn them 180 degrees and put back in, if you look at the pins as mentioned above they’re offset, one is higher than the other to prevent putting them in the light cluster wrong, but it’s easily done.

 

[I like Skol]

but it’s easily done.

No it isn't, just like the idiots who replace a headlamp bulb then drive around dazzling all incoming traffic until they fail the mot.
The offset pins mean the bulb is keyed to only fit in the correct orientation, unless you are particularly inept or ham fisted, in which case you somehow manage to force it to fit the wrong way!
OPs fault is almost certainly a bad earth connection after disturbing the light cluster.

 

[raleighnut]

Yep I'd say bad earth, seen a few really weird combinations in my years as a mechanic (all lights flashing when indicating was a good un.)

 

[gbb]

No it isn't, just like the idiots who replace a headlamp bulb then drive around dazzling all incoming traffic until they fail the mot.
The offset pins mean the bulb is keyed to only fit in the correct orientation, unless you are particularly inept or ham fisted, in which case you somehow manage to force it to fit the wrong way!
OPs fault is almost certainly a bad earth connection after disturbing the light cluster.

Have to agree, you'd have to probably damage something to put them in wrong.

 

[I like Skol]

Have to agree, you'd have to probably damage something to put them in wrong.

Plus there are two types of offset pins (and probably more?), the ones that are just at different depths and the type where the pins are not 180 degrees opposite to each other, now you would have to be really special to fit one of those wrong!