I built a relayed wiring harness for my recently purchased European headlights that I'm installing on my Canadian spec 1995 Corrado. The relayed harness is wired properly and performs as it should but I'm running into an odd problem with the factory wiring.
The low beam power wire at the factory headlight connectors has 4 volts on it when the ignition is turned on. This 4 volts is enough to trigger my relay and so the low beams on the Euro headlights turn on. This happens regardless of the headlight switch position. I've done quite a bit of troubleshooting and I've noticed that the 4 volts drops to 2 volts every other time I flash the high beams. This 2 volts is not enough to trigger the relay and so the low beams turn off. It's at this point that the headlight switch operates as it should.
I've already noted that my car came with daytime running lights. I found the wire that provides this voltage and disconnected it at a factory disconnect point. It was the yellow wire at pin TFL on the headlight switch.
Looking at the Bentley wiring diagram there's two sources of 12V coming into the headlight switch. One is the Red wire at pin 30 and two is the Black/Yellow wire at pin X. The 4 volts that turns on the low beams switches to 12V as soon as the headlight switch is turned on but only drops to 4 again after the switch is turned off which is still enough voltage to keep the relay latched and the headlights on.
Additionally, there's a 12V input to the high beam steering column stalk switch. As I see it any three of these 12V sources could be providing the voltage. I suppose the headlight switch or the high beam switch could be partially failed internally allowing the voltage to get to the wire that ultimately powers the headlights (Yellow wire at pin 56B of the high beam switch.
Has anyone seen this problem before? Any ideas or suggestions on how to proceed?
For reference I'm using the wiring diagrams on page 260 & 261 of the Bentley manual. The title of the diagram is Corrado starting 1991 Canada only. This seems like the best diagram for my car in my version of the Bentley.
Any help would be much appreciated!