No tail lights blowing 20 amp fuse

[Stema]

I purchased a 1969 Plymouth Satellite Sport a few months back and have been chasing a wiring issue that blows the 20 amp fuse (second from right). I end up with no parking lights. I have brake lights and turn signals. I separated the plug near the drivers side kick plate and it still blows the fuse. I am pretty sure it is a dead short to ground somewhere under the dash or in the front of the car. I have cleaned the front head lights wiring harness to ground, checked the bulbs in the front parking lights and made sure the front light plug assembly was clean and had good contact with proper 1157 bulbs. I have a new dimmer wheel because I was trying to get my dash lights to work. That did not make a difference. When I put on the parking lights, I get a heavy draw on the Voltage meter and it blows the fuse after a couple seconds. I took the bench seat out so I could get under the dash to look for a short with no luck. The cigarette lighter wire is hanging free and not touching anything but I do not have a cigarette lighter female connector installed. The radio does not work and is unplugged. Electrical diagnostics are not my strong points so I am looking for some advice and direction. Thank you in advance.

 

[vance.dykes]

If you disconnected the rear lighting harness at the driver's kick panel and it still blows the fuse disconnect the right and left front turn signal running light assemblies if it's still blows then you might have something in the dash you shorted out when you replaced the switch and if that's when it started blowing I would suspect that first what you could do is use a circuit breaker in place of the fuse because the circuit breaker will open and then as it cools it will connect back so you can have your hand on your switch and wiring assembly and see if it gets hot since you have the seat out

 

[WEDGEDYNAMICS]

You can put a bulb across the fuse to test a dead short. Trace the harness pull and tug on it till the light goes out that will be where the short is with no damage to the harness while you test it.

 

[72RoadrunnerGTX]

With the rear body harness disconnected, disconnect the forward lighting harness at the bulkhead connector as well. Still blows fuses? Short is between the headlight switch and the dimmer rheostat and or the bulkhead terminal “U”, Yellow wire with trace, L6A-18Y*. Disconnect the dimmer/rheostat, sounds like you just replaced it, need to verify there is no internal short there.

There was an optional “lamp on reminder buzzer” on that circuit (L6-18K) as well, if it’s there, disconnect it.

 

[vance.dykes]

If you just replace the switch I would say you need to take the switch out and then see if the fuse blows you could actually take and jump the power directly to the wire and see if the lights light up and that would eliminate the switch