Does anyone know or have experience of the bulb control units and if the various issue numbers are backward compatible?
In particular :-

86 - 928 641 603 05
84 & 85 - 928 641 603 04
83 - 928 641 603 03

Thanks in advance.
Roger
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Roger, I found a (minor) reference to the BCU on the CD's. Doesn't mention later years.

Lifted From pg 31 "Electrical Troubleshooting and Repair 928S":
Bulb Monitoring Unit
The bulb monitoring unit (behind CEB) has been revised. The monitoring of electric power for the tail lights is now accomplished with electronic components and no longer with mechanical reed switches, The new bulb tester (928.641.603.04) is fully interchangeable with earlier models.
Landsheer
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