Door Controls
I have yet to hear of a door ECU failing but you never know the history of your car! The ECU is in the double floor, underneath the passenger seat; it can therefore be affected should the car ever have been in deep water.
The ECU under the left-hand seat controls the left and right-hand door motors; it does NOT control the B-post actuator or the in-door actuator.
the operation of these two actuators depends upon the BSI and this can cause unexplained problems, especially if water gets anywhere near it. (e.g. is your engine bay fusebox cover properly secured?)
If your car won't start or the doors won't work even after a reset, try removing the link HS (or SH) in the BSI for 15 minutes and then replace it. This may also reset some of the preferences but should at least get you going!
This picture is a simplified diagram off SEDRE that shows the way the modules are connected together.
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The full wiring diagram is a work of art!
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