The other place to look for a problem is where the wiring runs through the trunklid arm. Often the opening and closing of the trunk over the years can cause wires to break where they have been bending.
Current ride... '13 GTI Wolfsburg
BMW's from my past...
'92 535i/5 '89 325ix/5
'98 750iL '86 325(e)/5
'95 740iL '84 318i/5