The flap control problem was first evident following the installation of the new heater box. But... the vehicle had sat unused for about a year prior to installation of the new heater box and the PBCU was acting erratically for a period of time after the new heater box was installed, energized and brought back on line... the PBCU initially failed to respond to any commands. The unit became responsive again after the vehicle's battery had been reconnected for 24 hours. Beckmann explained the initial unresponsiveness as possibly being due to the fact the vehicle's battery had been disconnected for that year period and leak down of capacitors.

The vehicle in question is a 1997 SL 600, production date 12.96. The vehicle donating the PBCU is also a 1997, produced in 04.97. The M-B number for the PBCU was the same from both vehicles: 202 830 12 85. M-B does sub that number to a ... 13 85 and then to a ... 14 85 but Beckmann states the units are interchangeable.

I have been using the Star wiring diagram for a 1997 SL and have seen no discrepancies between the diagram and what is on the vehicle.