Landseer

Love the 928. Runs and handles exceptionally with new front susp, new brakes/rotors/seals all around, oil leaks stopped and WP/TB job done. Cools, idles, blasts-off. I will save the shark, best I can.

Now, its time to shift focus to electrical. No stoplights; only right rear taillights/markers.


Issue appers to be with unit 928 641 60304. Mine is fried internally, part of the circuit board + the large winding. It is apparently costly. Meanwhile, my shark rescue budget is disappearing pretty quickly. It may be time to improvise until I can find an unscorched used one.

I've researched extensively past posts here as well as the wiring diagrams. Most are bypassing the warning function due to LED's, not jumping primary power function, best I can tell. They let their power run through the circuits in the box, but disconnect the warning.

The WSM and the circuit picture on the face of the BCU seem to conflict and have me confused about which terminals to jumper. ( update: it agrees, I just misunderstood at first)

Is there a clean way to bypass entirely?

It appears I can wire R&L taillight/markers directly from S1 and S2, respectively, keeping them fused properly at 28 & 29 on CE. Running a long jumper from them to the back of the car illuminates those lights.

I also think I can wire Stoplights directly from S6 to the back of the car.

BTW, contributing factors, looks like someone ran large bulbs for an extended period of time, plus, there is evidence of somebody hot-wiring the taillights and maybe stoplights directly from the battery without fusing (insulation premediatively stripped on wires entering lamp assembly). Have some melting of S2 wire as well.

Need some help on this one. Thoughts, anyone.

Thanks,
Chris

Imo000

Where is this unit located? I still might have one from the parts car. If I do and it matches your part, you can have it for $25 + shipping (~$10).

928ntslow

I have the same issue. I may pull the unit from another car, but am considering by-passing. The only reason that I am aware of to have this unit is it is integrated with the central warning circuit. Bulb goes out and you get a read out on the dash. Unfortunately, the dash doesn't tell all bulbs that are out. try your back up lights....bet they're out too. I may just leave mine in place and by-pass the back up and the brake lights as everything else seems to work. If I do this, the cluster comes out and the notification bulb for the brake lights gets removed.

So I say by-pass the bitch. My car is an 82 Euro and I could care less whether every little thing works.

Landseer

I think so, too. I think your early Euro has a different box, reed switches, that might have same pin-outs.

After a tad more study, I'm thinking I can bypass, but reverse later easily when a module can be procured. These diagrams are pretty challenging, but I'm ready to take a shot at this bypass.

Am going to unplug unit and try this at the female socket:

Temporarily bridge 12+9+1 for stoplights
3 + 5 for RR tail/marker
4 + 7 for LR tail/marker
Will leave 10 and 11 alone, as they appear to be the brake switches.

Only bad thing is no future notification of brake fault due to low fluid in master, best I can decrypt the functionality of this monitoring box.

Will report back.

heinrich

bypass

Landseer

Agreed. I can confirm bypass works as described for the 84.

12 + 9 + 1 for stoplights
3 + 5 for RR tail/marker
4 + 7 for LR tail/marker

I drilled-out the male connectors on the fried box, then separated them, then soldered them as ends of the various jumper wires. I'll apply some heat shrink tomorrow(today) and use the now-empty plastic circuit board box to cover the jumper wires. Next, need to get the right bulbs into the fixtures.

BTW, backup lights aren't monitored or processed by this box.

Maybe the best outcome of this excercise has been learning to read the wiring diagrams.

928ntslow

Yea, my box is 928 641 603.02...gonna by-pass it.

tigs001

If you happen to have the later model bulb control unit with 14 pins instead of 12, I worked out the following for a 928 641 603 09 from a 91 S4.

Bridge pins:

• 11 + 13 + 14 for stop lights
• 4 + 5 for right tail light
• 2 + 6 for left tail light

This worked for a RHD MY 91 S4. Originally a Japan delivered car, now in Australia.


The full pins assignments I worked out (but may not be correct, and I haven't tested them) are as follows:
1 - Not connected
2 - Left tail light globes x 2
3 - Not connected.
4 - Right tail light globes x 2
5 - From panel S25, via Fuse 8, via light switch, Right tail light
6 - From panel T11, via Fuse 7, via light switch, Left tail light
7 - Failure indicator for stop lights
8 - From panel S24, via Fuse 40, Reverse Light Power (unsure ???)
9 - From panel U14, stop light switch. GROUND
10 - Failure indicator for tail lights
11 - Right stop light
12 - From panel U24, via Fuse 35, stop light POWER 12V
13 - Left stop light
14 - From panel S12, Stop light active 12V, from stop light switch, brake pedal.