1989 740GL 109k Miles Since New

When the ignition is turned off, the battery will go dead in a several days. This has been going on for 10+ years and my cousin (from whom I got the car, and who bought it new) has been disconnecting the battery nightly as the "fix."

The dealer wanted $400 to troubleshoot and possibly fix the problem, but they wanted $700 to fix the locking system (it just was a bad hairspring in the drivers door lock I fashioned from thin piano wire), and $3200 to rebuild the transmission (it was just a bad overdrive relay I replaced), so I don't trust them much!

Now that I have the car, I've found that if I shut the ignition off, there is still a battery drain, but if I disconnect the battery (ignition off), even for an instant, the Radio Suppression Relay (I believe that's the one) mounted on the cooling system reservoir behind the battery clicks "OFF" and if the battery is then RE-Connected, the relay does not close (and the battery drain is ZERO) until the engine is again started.

Anyone know why that relay would stay activated when the ignition is switched off until the battery is disconnected?

I wouldn't mind learning what that relay actually does (I searched, but didn't find an explanation).

Is this a common problem? I suspect it's NOT a bad relay, but some circuit elsewhere. The car is equipped w/ a complicated "Clifford" anti-theft system (I have the receipt for $900 my cousin paid to have it installed it when she bought the car in 1989) that appears to be tied into everything, and I am loathe to try to track every invisible wire they installed back in 1989 (it's a rat's nest). I'm not sure if that is somehow tied into the relay and causing the problem.

I COULD install a small universal DIN relay that would ONLY allow the Radio Suppression Relay to get power when the ignition switch is actually ON, but I didn't want to go through the hassle to do that until I checked HERE for others who may have had the problem.

This is a 'Copy & Paste' LINK to a picture of the under-hood area with a red arrow pointing directly to the relay that (I think is the Radio-Suppression-Relay) and is sticking closed until the battery is momentarily disconnected: http://screencast.com/t/eeDRxL3Rh7Y

Thanks,
Bob