Bob,

Removed the seat bottom again and rechecked the readings. There is resistance across the male terminals, upgrading to a better multimeter I measured approx 85 ohms.

Your are also correct in grouding to the rearward B1 female terminal completes the circuit, I measured 12v when grounding to the seat mounting bolt. (this is on the driver's side with the key in #2 position and the belt unlatched.). So yes, it sounds like the belt circuit isn't being grounded properly.

Can you suggest where to look for a possible bad connection? Driving the car the belts lock/unlock randomly, making me suspect a loose connection or damaged wiring.

Also, just curious if the seats are wired "in series" or "in parallel". Since the problem occurs simultaneously on both seats, I'm assuming that both seats are grounded at the same point.

Thanks again, your help is greatly appreciated.

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1999 SL500