1997 E36 tail lamp troubles revisited

["Scott" <juggernaut@xxxxxxxxxxxxx>]

Just wanted to tell everyone about my experience with my '97 M3 brake lamp.
Last month I noticed the "1 brake lamp failure" message on the OBC every
couple days or so.  Naturally I checked the bulbs and noticed all were
working.  I immediately figured it must be a bad connection.  Well, I just
managed to get around to the repair over this past weekend.

I found the left rear brake lamp had one contact that was somewhat oxidized
and obviously the culprit.  I lightly sanded the two contacts on the
taillamp assembly and the small pins on the lamp holder with 800 sandpaper
to remove the corrosion.  Upon further inspection I already noticed the
oxidation had caused a slight burn and indentation in the metal contacts on
the assembly.  Not bad enough to warrant a replacement, but a cause for
concern down the road.  So, why is this happening to so many people and why
always the left lamp??

Upon further research I found that the wiring for the lamp circuit goes to
the left taillamp then is tapped to the right taillamp.  I'm guessing this
type of connection accelerates the corrosion on this contact due to the high
current draw through the left taillamp assembly.  Secondly, BMW made the
mistake of using two different types of metal for the taillamp contacts and
bulb holder contacts.  Anyone why deals with electricity will always tell
you to match metals when making connections.  If you do not, corrosive
effects will likely be present.

I recommend anyone with an E36 3 series to check their left taillamp brake
light once per year and lightly clean the contacts with a fine grit
sandpaper.  I do not recommend the use of a chemical agent to clean the
contacts as these chemicals can also cause their own corrosive effects after
time.  I also advise you to be very cautious if you want to bend the
contacts to make a tighter connection.  In most cases this is NOT necessary.
If you believe it is, be careful not to overstress the metal or it could
break off its plastic holddown.  I still believe that electrical systems is
one area where the Japanese car makers can teach BMW and even Mercedes a
thing or two.

Scott '97 M3


>
> Date: Mon, 22 Jan 2001 14:43:03 -0800
> From: "thomas eby" <thomaseby@domain.elided>
> Subject: 1997 E36 tail lamp troubles
>
> Sam-
> I had a similar problem, however my contacts were deformed and oxidized.
> Electrical short at the contact caused the oxidation which made
> the problem
> worse.
>
> What worked for me was cleaning the oxidation off the contacts of
> the light
> bulb _holder_ (the removable black plastic doo-dad) and the rear
> assembly. I
> used a small file. Be careful if you use an aggresive cleansing agent -it
> may melt the plastic. The oxidation was slight greenish in color.
>
> I also tweaked the contact tabs with a pair of pliers. So far,
> after about
> two months, no problems.
>
> Tom Eby
> 96 M3
> 74 02
> - --
>
> >Date: Sun, 21 Jan 2001 15:08:06 -0800
> >From: Sam Robertson <sam@domain.elided>
> >Subject: 1997 E36 tail lamp troubles
> >
> >Uggh... frustration mounts...
> >
> >So for some reason I'm plagued with my driver's side tail brake lamp
> >acting up.  I've taken it to the shop twice to no avail.  In fact, if I
> >see that 'brake light' warning again I think I'll stick my fist through
> >the dash. ;)
> >
> >Seriously, the mechanic had mentioned that they've seen this problem
> >many times and all but my case showed that the tail-lamp assembly had
> >become hot and deformed just enough to make the contacts between the
> >lamp and the assembly bad.  That's all fine and good, but this doesn't
> >look like the problem I'm having since we've verified the assembly is
> >not melted or deformed and the tail lamps have all been replaced.  What
> >does sort of convince me that I'm experiencing a similar problem is that
> >if I loosen the lamps and retighten them I'm good for at least a few
> >miles before the lamp quits working and the warning pops up.
> >
> >So here are my questions:
> >
> >* Can I replace the lighting assembly myself?  It seems simple enough.
> >* Where can I buy this that won't cost me a small fortune?  I've not
> >priced it from the dealer yet, but if there is just a 'known' place to
> >order this stuff, I would rather take care of it myself.
> >
> >------------------------------
>
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