From digest.v7.n354 Tue Sep 30 12:02:56 1997
From: Jim Cash <j.cash_at_sympatico.ca>
Date: Tue, 30 Sep 1997 08:47:44 -0400
Subject: Re: BMW 540i rear fog light

Richard D. Bucknam wrote:

> Hello Jim,
>
> Just read your post on 540i likes/dislikes. I pretty much agree with
> your list, but was most interested in your comment about installing rear
> fog lights. I would also like to see a rear fog on my 528i and was
> wondering how you did yours. Did you incorporate it (them?) into the
> brake light or add on a separate unit? If you did the former (which
> would be my preference) what did the job entail? Are parts for the
> conversion readily available in Canada, or how did you go about getting
> it done? Would appreciate any comments you might have. Thanks for your
> help.
> Dick Bucknam

Dick

I used the fog light that is part of most BMW rear lamp units. On the E39 it is the unused light compartment on the lower inside of each rear lamp.

Following is the proceedure I wrote for the dealer's reference. This applies to North American cars, and "may" apply to any others were the rear fogs are not provided.

Cheers

Jim Cash
London Ontario, Canada
E39 540ia

• remove from car, and knock out plastic insert where the bulbs go (lower inside compartment.)
• clean out any bits that fall into the lamp & then re-install in car.
• install 21 watt bulbs in the empty lower inside sockets.
• get 2 lengths of lamp wiring - about 15 ft long.
• remove the wiring connectors and install a pin in the appropriate empty socket ( first attach pin to new wires.)
• fish wires from rear up to the Lamp Control Module ( in front passenger

  outboard kick panel - behind carpet.) Need to remove rear panel in trunk,

  rear seat & back, and carpet rails so that wire can be installed under carpet.

  Follow other wiring - suggest using a metal rod ( straightened cloths hanger )

  to fish from rear seat to trunk. Stick rod backwards from the rear seat

  to the trunk - tape wires to it and then pull back. Caution - carpet rails have 3 fasteners (rear one has 1 bolt). These pull

  straight up - but be very gentle. Get under from end and pry close to the fastener.

  ( I had 1 fastener break )

Lamp Control Module

• pull carpet back & remove LCM from kick panel ( one bolt at bottom.)
• connect wire from Right rear fog to pin 1 on the X12 (large black) connector ( need open connector and install pin in socket).
• connect wire from Left rear fog to pin 15 on X38 (large white) connector ( need open connector & install pin in socket.
• connect another wire (small gauge - about 8 ft long) to pin 45 on X10117 ( small middle connector - also needs a pin in the socket - middle bank of

  connector slides out from others ).

• fish this small wire across to the fog light switch. ( follow the heavy group of wires under the dash - up at the top ).

Fog Lamp Switch ( this is the tricky part, unless you order a new Euro switch.)

• remove the wood dash trim & then the front panel that holds the light switches (3 small torx screws at top)
• disconnect all wiring ( parking lights come if the LCM is connected ( so leave disconnected till done )
• take panel & switches to a work bench.

  ( Use a towel to protect the front from scratches.)

• remove the 2 screws from the rear of the fog light switch.
• using 2 small screw drivers carefully pry off the back of the switch ( need to overcome the 2 small clips at top).
• with needle nose pliers grasp the grey centre shaft of the switch, and pull out.

  ( Front knob will fall off. - I never could pull it off from front )

• cut off the 2 long plastic fingers on the end of the shaft - that fit into the rear portion of the switch. Sand smooth.
• on the back of the switch "knob" are 2 small tabs at the outer edge, just

  inside the lip. Remove these so switch can rotate to the "rear fog" positions.

• the back of the switch that you removed contains the electric contacts. Pry the white switch portion out of the cap ( CAREFULL there are 2 small springs in the cap.)
• you will see 3 silver pins that go out the back into the connector. You need a 4th in the empty hole.
• use a short piece of steel wire - about same gauge as existing pins, & carefully solder it in place to act as the 4th pin. Leave it longer so that it will go all the way through the connector to get a good connection with the LCM wire you put in the other part of the connector.
• put switch all back together - don’t forget the small springs in the rear of the electrical switch .
• reinstall the switch panel in car.
• hook up the LCM.

OPERATION

• switch turns to 2 new positions (3 & 4). ( this assumes the off position as # 1)
• position 4 gives both front & rear fogs - including dash indicator lights)
• position 3 is designed for "rear only" in Europe - but the LCM software version 31 does not provide this, so position 3 acts like another "off".
• to get designations on the extra 2 position of the switch requires replacement of the front part of the switch. If you want this you might as well order a new switch. Otherwise you can live with 2 off positions and mark the front of the switch to suit yourself. Any marking put on the outside of the switch will not be lit.