Another thought - when I started to have troubles with our '90 744 TI a friend suggester that I take all connectors apart, clean them if possible, then add dielectric grease and zip tie any that I can.

I also checked and cleaned grounds - keep in mind - if a component does not have a ground wire, it gets its ground by its attachment to the engine or chassis. Engine ground straps can cause problems - check them and add an extra for good luck.

BTW - when I had troubles with my anti-lock brake light coming on sometimes when I hit a bump - it always went away on the next start-up - indicating a bad connection - my dealer kept my car for a week, pulled apart under the dash and in the trunk and even substituted the anti-lock controller from the service writer's car to try to find the problem.

I was only charger one hour's labor - they did ask me to replace the panels that they had removed.