Rear tail lighting order

[SigBoi]

Hey Everyone,

I just got a "check tail light" and "check brake light" warning today, 04 e53, and when I went back to take a look, my driver side bottom bulb was burned out with running lights on. I propped the brake pedal, and the light came on dim like the other running light brightness. The passenger side bottom bulb came on bright like a brake light is supposed to be.

Are the bottom bulbs supposed to be the brakes, or are all 4 reds supposed to go bright for brakes? I don't have another e53 to compare to, and I couldn't find any photos or video online.

Also, my passenger bottom bulb socket is a green one with 3 contacts and a dual filament bulb, while my driver side bottom socket is white, 2 contacts and a single filament bulb, same as the middle two sockets. No way that would work for both running and brakes with a single filament bulb right?

[andrewwynn]

Some of the bulbs are pwm controlled for brightness. I thought i noticed some very strange thing like the low filament unused on the lower lamp and pwm used for run light. Very strange

On our 01 x5s all four lamps are dual filament but the top lamp is only wired to use the running lamp. I rewired my top lamps so all four come on for brake.

[EODguy]

Isn't that the bulb setup for the euro rear fog light set? Hence the dual filament? Not sure if the NA X's have the wiring for rear fogs...

Not even sure that it matters or helps, just throwing it out there.

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[SigBoi]

Originally Posted by andrewwynn

Some of the bulbs are pwm controlled for brightness. I thought i noticed some very strange thing like the low filament unused on the lower lamp and pwm used for run light. Very strange

On our 01 x5s all four lamps are dual filament but the top lamp is only wired to use the running lamp. I rewired my top lamps so all four come on for brake.

Nice, how difficult was it to rewire for all 4 to come on for brake? I think that would look more uniform.

[SigBoi]

Originally Posted by EODguy

Isn't that the bulb setup for the euro rear fog light set? Hence the dual filament? Not sure if the NA X's have the wiring for rear fogs...

Not even sure that it matters or helps, just throwing it out there.

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I believe the euro rear fogs are in the trunk lid mounted tail lamps?

If everyone has white 2 contact sockets for brake, I’m not sure why I have a green 3 contact one on one side only. I’ll try to take a photo later today. But how would a single filament bulb work for both running and brake lamp duty?

[andrewwynn]

It was as pretty simple with a fairly big caveat: I've got an 01 x5 but with some 09 tail lights (post accident ). I noticed that the new model was wired for two filaments on the top lamp but the plug only was wired for low. I made a jumper from the bottom brake filament to the upper unused brake filament.


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[EODguy]

Single filament would only work with variable voltage I'd think low amount for running and high for brake function but I honestly don't know if it's setup that way:idunno:

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[andrewwynn]

I remember something very strange like the bottom bulb running pwm on the high filament for run. It was all weird back there. That may not be accurate it was a while ago. I just remember it was strange that the top lamp wasn't wired to use the bright filament just the dim .

Mine is now wired to light all bright filaments for brake. It's a lot of light make no mistake when I'm braking

[andrewwynn]

Originally Posted by SigBoi;

I believe the euro rear fogs are in the trunk lid mounted tail lamps?



If everyone has white 2 contact sockets for brake, I’m not sure why I have a green 3 contact one on one side only. I’ll try to take a photo later today. But how would a single filament bulb work for both running and brake lamp duty?

Previous owner replaced melted socket with the wrong type is the best guess. Pwm for running light full on for brake

[wpoll]

Originally Posted by EODguy

Single filament would only work with variable voltage I'd think low amount for running and high for brake function but I honestly don't know if it's setup that way:idunno:

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It IS set up that way. The LKM uses pulse-width modulation to vary the effective voltage across the lamp (the lamps filament acting as a averaging mechanism).

Pre-facelift cars have dual filaments and no PWM. Facelift cars use single filament lamps and PWM to alter the brightness.

This is why LED tails are both hard to source and often don't work well anyway on facelift (LCI) cars.