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1978 620 Tail light wiring


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Hi everyone!


My passenger side brake light would stay on no matter what happened, and the turn signal would not work as well. Driver's side works fine. When I took a look under the shroud around the steering column, there was a lot of gunk on the inferior side of the turn signal. I hit it with some electrical cleaner. I feel as if the switch was moving and engaging. Therefore, I believe the issue is at the taillight. Opening it up I have discovered rewiring and a burned Stop/Turn/Tail.


I've located the FSM wiring portion of the RH light here: 



Here is the RH taillight: 



Here is my interpretation of what is happening: 



I believe that the taillight was rewired incorrectly. I also believe that it has led to overload of the Stop/Turn/Tail as you can see below with the rubber being blasted away:



I do not have a multimeter, to test the stop/turn/tail to see if it is still working. But before that I have a few questions that if answered might correct my flawed thinking:

1. My interpretation of the diagram is that these connections need to be made before the 4-channel connector pin, is this true? 

2. If it is true, then several bulbs appear to be missing wires. Where are they?


Please let me know where I am getting this wrong. 


I will get a multimeter as soon as possible to see test these connections. 


Thank you so much, 



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Update on taillight issue:


So I took apart the turn signal switch and cleaned out all the corrosion on the switch contact points, checked all the wires and soldering points and there were no issues there. Unfortunately I did not take pictures of the corroded portion: 

Here is my switch: 


Undid the two screws on the left side of the switch to get the contact points and the bronze pieces that make contact with the springs. Put dielectric grease on them as well. 

After this, the turn signal still would not work. I ended up replacing a bulb, and VOILA it worked. 

The system was working well. The turn signals worked well after that but my brake light was still not working. 

Here is the wiring set-up made by PO:



I maneuvered the wires around in attempt to get the brake light on the right to work and ended up blowing a fuse.

After this, both brake lights stopped working. 

I ended up replacing two fuses, a 10A and a 15A in the top and bottom right respectively. 

I expected this to fix the brake light problems but it did not. 

I wracked my brain around why it would not work for a week. Eventually I checked the connections at the brake light switch to find one of the connections completely broken. I must have broken it somehow, because the brake light worked before. 




I replaced the wire and the brake light works! 


The right brake light does not work still as messing with the wiring caused me to blow through two fuses. 


I have ordered a replacement OEM 4-pin tail light from a Pull-a-part in Oregon because the color coordination did not match and I do not trust my ability to rewire the light in accordance to the wiring diagram that I posted earlier. 


Hopefully this replacement taillight fixes everything. 


In summary: 

1. Cleaned turn signal switch.

2. Replaced right front turn signal bulb.

3. Replaced wire to brake light switch 

4. Reordered a 4-pin taillight to replace PO's questionable wiring. 



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