Tail lights

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2800cs

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I have a problem with having my tail lights not working.

Not all of the bulbs at one time.... but randomly

Ive polished all the mating surfaces but they still intermittently go out.

Has anyone here somehow fit newer more traditionally gounded sockets to the stock housings?
 
That sounds like a ground problem. Check the wire inside the housings that connects the grounds for the sockets together, as well as the copper strip along the back of each housing. Also, follow the ground wire to the spot inside the trunk where it actually grounds to the chassis and check for corrosion.
 
Ohmess said:
That sounds like a ground problem.
Click to expand...

True, it could be a ground problem. But it could be other things as well; the sockets for e9 tail and brake lights are kind of "mickey mouse".

I tried grafting off-the-shelf, generic sockets into my stock housings, but never liked the result.

My second generation solution was to glue LED arrays from SuperBrite into my housings. See: https://www.superbrightleds.com/moreinfo/tail-brake-turn/1156-led-bulb-36-led-pcb-lamp-ba15s-retrofit-car/501/#/tab/Specifications

Although these arrays come wired to connectors that can plug into your sockets, I cut off those connectors and attached the wires directly to my stock wiring harness. Admittedly, this is not a solution for purists, but I feel it's better than relying on 45 year old, corroded, light-gauge sheet metal contacts to protect my coupe from getting rear-ended.

These things look like:

1156-pcb-x36_mm.jpg
 
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Jmackro,

Thanks I think I will give that a go.

Its definitely a ground issue. Ive soldered additional grounds to the lights and Ohmed all the connections not so long ago... everything works for awhile but its very finicky.
 
Possible ground issue?

2800cs said:
Jmackro,

Thanks I think I will give that a go.

Its definitely a ground issue. Ive soldered additional grounds to the lights and Ohmed all the connections not so long ago... everything works for awhile but its very finicky.
Click to expand...

Another possible source of winking out is the positive contact. They are a springy gizmo that does three things at once- when they are working, that is.

1) It holds the lamp in the socket at the right height for best reflector efficiency, and

2) Pushes the bulb pins against the ground plate to make a ground connection, and

3) Conducts power to light the lamp when you brake, turn, etc.

The base contacts are a brass alloy, tempered for springiness. When they get older, any slight moisture causes corrosion and oxidation, and increases the resistance between the spring contact and bulb base contact - that lump of solder.

This is the cycle they go through- slight corrosion causes resistance and this causes slight heating in the brass contact, heating the metal softens the temper, which reduces spring force against the bulb, which increases resistance, heats the spring contact, relaxes the temper even further, and so forth. And if the reflectors are corroded, they won't reflect much light out of the lens, either.

Installing new bulbs, especially high output bulbs, and bending the spring contact up towards the lens will eliminate some of the problems, but it can be overdone so proceed carefully if you go at it yourself.

I think the best answer is to restore the reflectors to their original shiny state, and upgrade the lights for a larger and brighter appearance. Clean the lenses inside and out, too.

I have done this for my neighbor to his 1973 3.0 CSi. Would be willing to describe the process and results if you are interested. It is a hell of a process, way more than for 2002 or E28 or E30 lights, but hell, the coupe is a hell of a lot more car, isn't it? I think I even have some pictures somewhere...

Andy
 
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Poor connections, check the fuse

I had a bulb in my 1967 VW beetle that would not light. Voltage checked ok, ground connection seemed ok. Bulb tested ok. I finally realized that the old style fuse, being the ceramic plug with exposed fusable link wrapped over it was corroded just enough to prevent any real current from flowing. When the bulb was put in, the voltage would fall to zero, but with no load, the voltage was the same as the battery, 12 volts. Cleaning the fuse contacts fixed it.
Bottom line, check ALL the contacts.
 
Corrosion check

Amen to that!

Those old ceramic fuses are prone to causing lots of weird behavior. My E28 has them, and I have to maintain them to keep things working. Bending inwards on the tabs that hold them helps, along with spinning the fuse in the tabs to dig a groove for better contact.

Many problems can be avoided by replacing fuses every five years.
 
Those old ceramic fuses are prone to causing lots of weird behavior. My E28 has them, and I have to maintain them to keep things working. Bending inwards on the tabs that hold them helps, along with spinning the fuse in the tabs to dig a groove for better contact.

Many problems can be avoided by replacing fuses every five years.
Click to expand...
Got me an E28 also and have the same issues. I use small rubber bands that I put around each pair of tabs that holds them tightly on each fuse.
 
Mo Brighta said:
Amen to that!

Those old ceramic fuses are prone to causing lots of weird behavior. My E28 has them, and I have to maintain them to keep things working. Bending inwards on the tabs that hold them helps, along with spinning the fuse in the tabs to dig a groove for better contact.

Many problems can be avoided by replacing fuses every five years.
Click to expand...

So correct :-)
In fact I'm also doing this "nerd thing" of spinning fuses about once a year due to said corrosion. And as well the quality of the old ceramic fuses contact areas are so bad that you could end up with all the current passing through less than millimetres (mm) area resulting in voltage drop to the consumers.

So folks! Spin the E9 fuses ;)
 
On the fuses contact points I use contact spray which contains oil.
There use to be something called contact grease in tamiya r/c cars which was a white grease kind of thing that would stop the carbon build up on the speed controller, which was a variable resistance. I could never find it again....
 
One other comment to add to Mo's thoughts. Cleaning the contacts with some form of phosphoric acid (I use naval jelly) really helps improve conductivity.
 
taillights

Last time I had a problem with intermittent operation of my tail and brake lights, like one brighter than the other, or not working at all.... I traced all wires back to front, improved all ground attachments, but the final piece of the puzzle was ALL new correct BMW bulbs in the sockets. Done.
 
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