4 Rewiring the Car Wiring Harness to the Tail Lights

Now that the tail lights have been modified, it will be necessary to modify the stock wiring harness. As stated in the introduction, both US and Euro/JDM tail lights use the same connectors. Only the pinouts differ. The Euro/JDM lights have two extra wires in the connector- pins 1 & 3. This procedure will outline the procedure for adding two new wires to the US spec harness.


4.1 Remove the rear interior panels and locate the wiring harness going to the lights. (Figure 16). Unplug the harnesses from the lights. Note that pins 1 & 3 do not have connections.


Figure 16


4.2 New wires and spade connectors will be inserted into the empty pin sockets to add the two new circuits (Figure 17).


Figure 17


4.3 Take the 1ft section of green 16 gauge wire and cut it in half. This will become the two new pigtails for pin 1 (Figure 18). Pin 1 will be spliced into pin 6.


Figure 18


4.4 Using wire strippers for 16 gauge stranded wire, strip 1/4" of insulation from ONE side of the new 6" section of green wire (Figure 19).


Figure 19


4.5 Using a soldering iron and solder, tin the bare wire by applying a small amount of solder to the bare wires. Insert the tinned wire into the spade connector and solder it into place (Figure 20).


Figure 20


4.6 Label the two ends of the pigtail as follows (Figure 21):

  • Spade end: 3
  • Unstripped end: 6


Figure 21


4.7 Insert the new wire/spade into the empty pin 3 socket (Figure 22). Ensure the channel of the spade connector is oriented so that it faces the connector tab.


Figure 22


4.8 Next, loop the new wire and tap splice the 6 end to the Gw wire coming from pin 6 of the connector (Figure 23).


Figure 23


4.9 Repeat the same procedures for the other connector. This will complete wiring up the two middle sockets as Running lights.


4.10 The next step will be to make a new harness for the brake lights. Take the 6ft length of 14 guage blue wire and measure and cut a 46" section from it (Figure 24). This will become the new brake wire joining the two tail light assemblies. The remaining section will become the new brake wire to be tapped into the 3rd brake light.

Figure 24


4.11 Using wire strippers for 14 gauge stranded wire, strip 1/4" of insulation from each side of the new 46" section ONLY. (Do not strip insulation from the 26" piece of wire). Tin the ends and then solder a female spade to each end. Once that is complete, use a 16-14 gauge tap splice and splice the 26" and 46" sections of wire together approximately 2.5" from one of the spade connectors (Figure 25).


Figure 25


4.12 Next, label the spade ends of the 46" section as 1 (Figure 26).


Figure 26

4.13 Next, cut 4 1.5" pieces of 1/4" heat shrink and a 40" and 20" section of 1/4" sleeving. Slide the 40" piece of sleeving over the 46" piece of blue wire (Figure 27).


Figure 27


4.14 Centre the sleeving over length of the wire. Slide a piece of the heat shrink or each end of sleeving leaving about a 1/4" of heat shrink extending beyond the sleeving. Using a heat gun, shrink the heat shrink and seal the ends of the sleeving. Repeat the same procedure for the other wire. When completed, the result will look like Figure 28.


Figure 28


4.15 Run the new 46" wire harness along the OEM harness from the left tail light to the right. Ensure that it is spaced evenly between the two tail lights and secure using the metal OEM wire stays holding the OEM harness. Insert each spade connector into the empty pin 1 socket of each OEM tail light harness (Figure 29).


Figure 29


4.16 Take up the slack and neatly secure the new pin3-6 pigtail and new pin 1 wire with a wire tie (Figure 30).


Figure 30


5 Tapping into the 3rd Brake Light Circuit

5.1 The next step is to splice into the 3rd brake light wire to bring power to the new pin 1 brake lights circuit. Remove the left interior panel covering the left rear wheel well. Route the 26" blue wire coming from the new left tail light harness under the rear deck. Have the harness emerge from under the deck along the rear edge of the wheel well. Locate the OEM harness for the 3rd brake light. It will be located under the speaker deck. Using a 16-14 tap splice, splice the new harness into the Gw wire aft of the OEM 3rd brake light connector. Once complete, the new wiring harness will look like Figure 31.


Figure 31


5.2 The last step is to electrically separate the old Brake/Turn/Hazard circuit from the OEM tail light harness. In the US setup, the rear brake lights are electrically connected to the turn indicators and hazards and all 3 circuits use the same bulbs in the red lenses. Since the Euro/JDM lights have separate amber turn indicators/hazards, the old circuit needs to be electrically removed from the OEM harness in order for the new lights to work properly. This can be done at the harness for the hazard switch assembly. Remove the instrument cluster shroud by removing the 4 screws holding it in. Use a #2 Phillips screwdriver. Two screws will be directly under the left and right side switches and the other two will be under the shroud just above the speedo and tach gauges. Once removed, pull the shroud off. Locate the harness for the fog/hazard switches located on the right side. At the switch side of the connector, locate the Wg and Wr wires. They will be paired into the same pin at the very end of one side of the connector. Cut the Wg wire (Figure 32). This will cut the signal coming from the brake pedal switch to the hazard switch. Once this is done, the brake circuit will now be electrically removed from the OEM harness going to the tail lights. This is why it was necessary to tap into the 3rd brake light to power the new brake lights since the 3rd brake light is not electrically tied to the hazards.


Figure 32


6 Install New Tail Lights & Test

6.1 Using a 10mm socket and rachet, remove the 8 nuts that secure the OEM tail lights to the chassis. Install the new Euro/JDM lights and plug the new modified connectors in to the new lights (Figure 33).


Figure 33


6.2 Test each circuit (Running, Brake, Turn/Hazard, Backup) to ensure that all the lights work properly (Figure 34).


Figure 34

The picture shows only the running lights and hazards on. The small square inside running lights appear to be much brighter that the running lights in the brake light section.


[Go to JDM Tail Lights Page 1]


[Cargo Area Lighting] [LED Evaluations] [Instrument Cluster Lighting]

[Interior LIghting] [Project Starion Home]