How to repair 3rd tail light broken wiring 

Contributed by: Gert Carnewal

Below you'll find the DIY, first an explanation of what we are about to do. 

Drawing #1 shows the cross-section in the original situation. 
Inside the car, the power for the 3rd brake light is fed via two black wires which are hidden behind the rubber window seal. The yellow part in the drawing are the two copper conductors which are embedded into the rear glass. On the inside of the car, the two incoming wires (+ and -) are each soldered onto one conductor which takes the power to the outside of the car. On the outside, the two connectors for the 3rd brake light are soldered onto the conductors. 

Drawing # 2 is the same cross section but where one of the two embedded conductors is broken. Resulting in a voltage interruption.

Drawing #3 shows how to repair the broken conductor. 
You have to bring the wire from the outside, through the rubber seal and connect it to the incoming wire on the inside. By doing so, you "override" the broken conductor. Although the 3rd brake light housing and the outside rubber seal already prevent water leakage, it is better to apply some sealing compound where the wire enters the cabin. 


Step 1: Remove the cover of the 3rd brake light. Gently pull upwards. No tools needed. 

Step 2: Remove the 2 nuts with the use of a 10mm socket wrench 

Step 3: Remove the 3rd brake light housing. 

Step 4: Remove the rubber seal in the middle, where the brown and black wire are. 

Step 5: Locate the broken conductor. In most cases, the broken conductor is visible from the outside of the car. If you don't find it, do a continuity test between the incoming wires (soldered to the conductors) and the connectors of the 3rd brake light. Of course, you can always repair both conductors. 

Step 6: From inside the car, remove the rubber seal. Make a small hole in the window sealant. This works best with an awl or a small screwdriver. 

Step 7: Cut off the wire on the outside. 

Cut as close as possible to the glass to keep the maximum wire length. Strip about 1" of the wire insulation. Tin plate the wire with the soldering iron.  Take a small set of pliers and push the wire from the outside through the hole you made in the window sealant. Use some duct tape on the side of the roof so you don't damage the paint. Once the wire is through the sealant, cut it off so there is only 1/4" uninsulated wire. Solder this wire onto the incoming wire. Don't solder onto the conductor.  Solder the wire onto the top of the incoming wire. This, to avoid heat dissipation on the rear glass.
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