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

Having to give the dash a tip to wake up the voltmeter is a rather common problem. It doesn't indicate any charging issue just an old sticky gauge. My '88 does the same thing.

Check your harmonic balancer,could be slipping when cold then grabbing as it heats up. With that kind of mileage on the vehicle it could be time to replace. Put a chalk line across the crank,rubber to the inside . Easy way to see if it is slipping.

i ordered one (harmonic balancer) today. thinking it could be contributing to the problem. How do you explain the tapping on the dash after about 5 minutes and the dash gages coming alive, lights brighter etc. thanks 240 guru for working with me on this one. I will let you know if the balancer does the trick. Pls answer the question above if you have an idea.

Check the voltage at the D+ wire to the alternator and the output at the
Battery cables. You can have poor/dirty/corroded connections and/or connectors
in the battery cables. Bad ground wire connections.
Loose altenator belt, and bad alternator bracket bushings.

All this stuff is treated over and over and can be found with the search
engine.

Bill

thanks bill, I was really wondering about the tapping on the dash part. My charging system works fine once it has warmed up. I am taking 240 guru's suggestion to replace the harmonic balancer. I believe that is bad but i also believe I have a continuity problem some at the connections on the backside of my instrument cluster. BTW I replaced the wiring harness about 3 yrs ago. Thanks JMSH