The SRS Air Bag Warning Light has come back on 6 months after being reset by the local dealer. The first time it came on was immediately after leaving our local car wash where I have suspected a heavy knee or even someone standing on the power seat controls of our 1999 528i. The seat control housing was broken. The dealer has informed me that I could be looking at a grand plus to have them track down where a sensor might be loose or broken. Any ideas on where to start tracking down the fault in the sensor wiring and cutting down the search time the dealer is ballparking at $130 an hour?