<E28> More Brakelights: DIY factory-style upgrade... very cool..

["Aaron Bohnen" <bohnen@xxxxxxxxxxxxxxxx>]

Hi everyone,

Having remembered some flicker of discussion about the extra, unused bays 
in the rear brakelight assemblies of our E28's I investigated a little 
more carefully a couple of days ago. Sure enough, the lowest, most inboard 
light bay in the brakelight cluster is a dead hole in the plastic. There 
are spots there for the bulbs, including busses for power and ground. But 
there's no power to those fittings. 

Presumably in the Euro version of the car those inboard lower bays were 
used as a rear foglamp. (Not wired that way in the north american ones - 
they are not powered with the foglamp circuits.) Possibly with 
differently-colored lenses, etc. etc.

Well, to make these bays work with the rear brakelights all that is needed 
is to pull out the plastic castings in the way of the bulb positions 
and supply power to the upper buss that feeds that inmost lower bay.

The rear brakelight assembly is powered by a six-conductor modular 
connector. On the north american cars there are only five conductors 
present. The missing sixth would have powered the rear fogs - and in this 
mod will power the secondary rear brakelights.

I didn't want to bugger around with the system too much, preferring to do a 
nicer a la factory-ish type of job. Here's what I did:

1. pull factory connector out of rear brakelight assembly receptacle.

2. locate missing conductor in the connector - it will be the lowest, most 
inboard one.

3. remove existing brakelight female spade connector from inside factory 
"molex"-style connector. This is the outermost lowest connector in the 
factory "molex"-style connector. A thin slot-head screwdriver will easily 
disengage the little tab and the female spade connector will come out 
easily. 

4. peel back sticky tape in factory wiring harness a little - 4" or so. Cut 
off factory brake connector with about 2" or so of wire. This is the 
outermost, lowestmost connector in that assembly.

5. Make another little wire and female spade connector that looks the SAME. 
JUST THE SAME. The wires can be different lengths, but make the female 
spade connector ends look as close as possible to identical. This is the 
tricky part - the spades they use have very long bodies. I'd suggest 
getting the correct BMW spade connectors first. I don't have the part # 
since I used some other ones that I already had in my connector box and was 
able to modify to suit. Go to your dealer and ask for the female spade 
connectors that fit the rear brakelight assembly. I'd get more than only 
two - they are easy to wreck.

6. Now reconnect both little leads with female spades back to the factory 
wiring loom in the car. You could just use a generic butt splice fitting 
here, or you could go all out - like I did. Silver solder, lots of 
shrinkwrap, etc. etc. My attitude is that you might as well do it like 
you're proud of it. If you don't share that perfectionist streak just use a 
sensible means of reconnecting them.

7. Put the factory brake light female spade connector back into the 
"molex"-style connector in it's correct spot, in it's correct orientation - 
the female spades do not lock in correctly if upside down. Be careful.

8. Same thing but use the additional lead that you made - this one goes 
into the formerly unused space in the "molex"-style connector.

9. Repeat for other side.

10. Insert suitable bulbs and holders into the formerly unused innermost, 
lowermost brake light bays.

11. Done! Check that all works as it should.

Seem complicated? It does because of all the talking about it. Really the 
job is simple - you are jumpering the brakelights to the unused spot in the 
factory "molex"-style connector with a little lead and a female spade 
connector. 

Once you pull the factory connector out of the back of the brakelight 
cluster it will all become very very clear.

Outcome: much better (x2) brakelights.

Cost: whatever you spent on the female spade connectors and 4" of wire.

Downside: None.

Verdict: try it!

best regards to all,

Aaron

p.s. - or you could just solder a jumper from brake light buss to 
unused buss, but soldering on galvanized is always a pain unless you can 
scrape right down to the bare metal - and heating the pieces is very 
difficult without endangering the underlying plastic. However, I'm sure it 
could be done. But my way's better. :>
___________________________________________________________
Aaron Bohnen                     email: bohnen@domain.elided
- -Ph.D. Candidate, Civil Engineering Department, U.B.C.
- -Technicraft Engineering Services

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