Classic/Antique Car Repair: parking light and now dimmer switch, fuse box, headlight harness

Question
I have a 69 firebird 400 engine,I turn on the headlights and one blinker light stays lit on the dash.But also the front parking light on the drivers side will not work.All blinkers work when i turn them on.Now with that said.I just found out the dimmer switch is very hot and i have to replace that.My son says its a ground issue.But i have taken all the tape off the front harness and did not find any bad parts.I have also taken apart the fuse box and everything looked ok there also.I need help to get this car on the road.Ive been dealing with this issue for a month now.Would a new headlight harness be the answer?I need help PLEASE.Thanks John

Answer
I think you have two separate problems.  First, the dimmer switch: any switch that gets hot is failing (or has loose or dirty contacts on it), so replace that switch and make sure all the wire ends are clean and in good shape.

On the blinker indicator etc, your son is right, the problem is that the metal bulb socket in the left side blinker light is not making good contact with the body - probably due to rust where it is mounted, or if there is a ground wire on it, it has come loose or broken, or the terminals are dirty or loose.  To prove this to yourself, take a separate wire and temporarily hold one end onto the metal part of the bulb socket while the other end is on some known good ground like the bumper or the negative terminal of the battery.  (Take the lens off so you can get at the bulb socket to do this) and I'm betting that while you have the socket well grounded, the problem will clear up.  The fix is to find out what is wrong with the ground and do a permanent fix.  

With old cars, most of the parking light housings have to have added wires put on them to get a good ground, due to rust and dirt building up over the years, or due to the bulb socket getting crud between it and the housing.

Dick