On real cold mornings, the charging circuit on my car (1987 740 with 285K) does not work initially. After the car warms up at idle and maybe a slight tap on the dash, (I know this is not a good fix), the gages come to life and the heater picks up and lights get brighter. I have checked the charging circuit once the gages begin to read and everything is working fine. Where would be agood place to begin my investigation to find the a loose connection that is preventing the alternator charging circuit from charging prior to warm up. could I have a loose connection in my instrument cluster if so which one would it be. I only have this problem during the winter months when the temp is below 30 F at initial start up. Could it be a relay. I do believe it is in my instrument cluster due to the tap on the dash approach after the car has warmed up. Sorry for the lenghty discussion but wanted to give as much information as possible. BTW the key tumbler seems fine with its connections.
JMSH