On these tail lights, do the stop lamps(bulbs) go on the top or bottom holes of the housing? Also, are both lamps supposed to be on when running lights are turned on? When I turn the switch on, both bulbs are lit, one bright and one dim. Is this correct? I don't want to create an electrical problem if this is not right. Thanks, Chumley

 

Both upper and lower bulbs are wired the same and operate together. All A-bodies use 1157 bulbs with dual filaments. One filament is the tail light and the other is the stop/turn filament. The turn signal switch controls whether the stop/turn filament is lit when both brakes and turn signal are on simultaneously.

The 1157 is a bayonet base bulb with two contacts on the base. The bayonets are offset so the bulb can only be inserted one way.

 

Thanks, so are you saying that with the running lights on(no brakes or turn signal on) that all four bulbs should be the same brightness? And when the brakes and/or turn signal is on, both lamps(whatever side turn signal is on) both lamps should turn on and off at full brightness? Right now, with just the running lights on, one lamp is bright and one is dim.(same for both sides) I guess I'll just get a new wiring harness, I know the one in there is not correct. Also, are those lamp sockets acting as a ground against the back of the housing? Thanks Chumley

 

Yes

Yes again. The second filament will be used. If the running lights are on, both filaments will be lit.


This may be as simple as a bad ground. Being cheap, I'd trace the wiring and check the grounds and connectors before throwing an expensive wire harness at the problem. A factory Chassis Service Manual is your friend.