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From: Richard Cartledge <>
Date: 30 Jul 97 17:39:28 +0100
Subject: re><E28> retrofitting OBC ???

re><E28> retrofitting OBC ???
Olav Berthold <> wrote.....

>Fellow enthusiasts,
>f I remember right, the subject of retrofitting an OBC to an E28 was =
>already discussed some time ago. But I didn't own one of the beasts =
>So could someone please describe/re-post the procedure plus additional =
>parts that are needed ?
>If there is a FAQ for this subject, I would be interested in it as well.

>All hints and tips are very welcome.

>Olav Berthold
>(Hannover, Germany)
>88 535i 5-speed

Hello, I retrofitted an OBC into an E28 3 years ago, and have discussed it on the digest about a year ago.

It was a long time ago now, but I used a Haynes Workshop manual to workout the wiring colours and postion of the various parts.

I found a BMW breaker in the UK called BM BITZ in Essex, I took an OBC out of a 82 520i and put it into my '86 525i.

The PARTS you will need from the donor car are.....

The display keypad assembly - where the clock goes, need to get bezel and new hazardlight/rear screen switches

Brainbox Contol unit - under steering column in black plastic holder

Brainbox munting bracket holder -behind the steering column panel in fornt of driver's knees

Chime gong speaker - mounted in brainbox holder

Temp sensor- mounted in front towing hook plastic flap


There is a thick multipin cable which goes to the brain and the spare socket on the back of the instrument cluster

Another similar one goes between the other socket on the brain and the display/keypad assy.

I just used my own speaker cable to the temp sensor as the car had crashed and snapped the original cable.

The power wire went to the white plastic array of connetors above the pedals. The connectors only fit the correct sockets on the panel.

There are two green wires behind the instrument clust connected together, these are split apart and plug into the green wires from the brain - these are foir the CODE immobiliser function.

Thats all I can remember.
Hope it helps, Richard E28 5 Series Fazine

PS I didnt use the steering column control stal as they wernt on the '83 models. There are two types of OBC they improved in 1984/85 Mine didn't wrk at first and the brain had a blown 20mm glass fuse in it.

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