Tail light issue

[e30pwr]

Alright, having now been stopped with two different stories on what is going on with my pass side tail light.

What happens is normally one of three things, and on the check panel for all of them the "(!) brake lights" is on:

1) the brake light does not illuminate when I hit the brakes.

2) i hit the brakes and all three check panel lights illuminate on the left side( aka all the rear ones) come on and from what I have been told by the cop, the whole tail light goes dark, no lights are on

3) the check brake light is illuminated, however no issue is to be found with them once i stop and check.


This brings me to one hell of an electrical nightmare that my sick brain can't seem to wrap itself around. I have been told by two different cops, on two difference occasions after thinking I have fixed it, that either all the lights go out, or the brake light does not come on. I was just playing with it and have verified that the bulbs are all good. I re-pushed in the connectors that go to the tail light bulb holder, and they are all in solid, loose, but in there good. my next mission will be to insure they stay in there with hot glue or something of the sort, idk for sure.

So I come to r3v hoping someone understands the diagrams and electrical systems more than I. I partially think that it is a bad ground, but from looking at the diagrams the turn signal, and side marker should go out as well. I also partially think that it is an issue with the "check panel switch" that is in the diagrams as well.....help?


diagrams for reference: http://www.armchair.mb.ca/~dave/BMW/e30/e30_86.pdf

I am also looking at the diagrams in the bentley manual.

[McGyver]

faulty brake switch?

[bimmer206]

I'm having a similar problem. All my tail lights were out (breaks, backup, and day lights). I checked the bulbs and replaced a few burnt ones. Checked the fuses found a couple were blown (replaced them), and then i replaced the break light switch (connected to the pedal). This has now fixed the day lights and back up lights but all three of my break lights don't work (86 325 in case you were wondering). My only clue is that the passenger side turn signal blinks twice as fast. What could be causing this? To e30pwr check for blown fuses with a multimeter and replace your break light switch if need be (i read they fail often).

[Mo Brighta]

rear light issues

Three things I would check.

1- Bulbs with brass base installed somewhere - definite no-no, must have nickel base.

2- Loose ground wire somewhere.

3- Weak bulb base contact, or corrosion - if loose base contact, it can be bent up for more 'spring force' and better electrical contact against the bulb. You can tell by pressing the bulb in as if to change it, and if it returns weakly, try increasing the base contact pressure by pulling it up towards you. CAREFULLY. If corroded, clean with a pencil eraser or other method.

Also check all fuses and wire harness connectors, remove and install to ensure good connections.

Good Luck!

Andy the tail light guy

[e30pwr]

lols, well I have determined that striking the tail light in question seems to help the issue. therefore i am thinking it is no longer a brake switch or wiring issue. time to test the metals and all the bulbs for corrosion....

[Mo Brighta]

Maintenance technique ?

... striking the tail light in question seems to help the issue ...

OK, that's what we call 'Percussive Maintenance', and it got me out of a ticket some decades ago when my1962 typ 1 VW was having issues with the left tail light.

NY State Patrol stopped me for this exact same thing on my way down SR 22, tripping from Berkshire County (known as the 'BEEE-utiful BERK-shires') to Westchester County one night. One of the few nights I was close enough to the speed limit to avoid a ticket. (Not so lucky other nights, ending up passing a 'plain brown wrapper' at closer to 100 than 90 in the same car, and no, it was NOT powered by any stinking 36hp four banger, it was a 90hp four banger out of a Porsche 356B).

Good stiff whap to the fender restored (temporarily) the tail light; with a grimace, he urged me to 'Get it fixed RIGHT.'

Come to think of it, this may have been the event that motivated me to become the Tail Light Guy... I have been screwing with tail lights and head lights ever since.

Sorry, I got kinda long winded there, let me know if I can help. I think I can help; let me know if you want help.

Andy

[e30pwr]

haha, thanks a lot man, any advice for checking what metal besides magnetism?

[Mo Brighta]

haha, thanks a lot man, any advice for checking what metal besides magnetism?

Yes, color.

Brass are brass color, Nickel are silver color.

Neither are ferrous, so a magnet will not stick to either one.

[e30pwr]

Yes, color.

Brass are brass color, Nickel are silver color.

Neither are ferrous, so a magnet will not stick to either one.

and I'm now 90% sure that you have found the issue. half of the driver side bulbs are brass and one on the pass side are brass. I'll post for sure when i get the full set replaced.

[e30pwr]

new bulbs didn't do the trick. at least i know they are all solid now. worked on all the connections in the tail light housing. It'll be next week before I can get ahold of a multimeter to check out the relay panel box voltages etc.

[bimmer206]

If your hitting it to make it work it sounds like the metal tabs on the back of the taillight assembly are corroded. These tabs provide the ground and it sounds like when you hit the lights you are making the connection. Clean all these tabs and make sure they are touching metal when you put the assembly on.

[dashboardmonkey]

bulb base color does not matter, the check system is just not that sensitive

clean all contacts thoroughly, check ground points, try cleaning the contacts on the check system resistor box unit thing in the trunk close to where the stock amp is or would be located, if you have a vert this "box" is behind the rear seat inside the car

[Mo Brighta]

bulb base color comment

bulb base color does not matter, the check system is just not that sensitive

Base color isn't the real issue. Check relays don't care what color the metal is, they monitor current to confirm bulb operation. Corrosion caused by metal dissimilarity is the issue. The way it normally proceeds, corrosion increases contact resistance, decreases voltage to the filament, reduces current, lowers light output, and triggers a check panel fault.

clean all contacts thoroughly, check ground points, try cleaning the contacts on the check system resistor box unit thing in the trunk close to where the stock amp is or would be located, if you have a vert this "box" is behind the rear seat inside the car

Absolutely, the lighting circuit includes ground wiring too, not just supply wiring. Clean and tighten all ground wire (brown) connections while you are in there. This is good advice, as it addresses corrosion directly. Removing and reinstalling connectors will usually scrape through any corrosion present, making a better connection with low resistance!

Hope this helps, and good luck.

Andy