Read this entire post carefully, and beware there is a possible danger in doing this mod. I will take no responsibility if damage occurs. This could possibly void your warranty, etc. etc. etc. This post is for information purposes only. Proceed at your own risk.
I completed this modification to my own car
and have had perfect results. The additional two reverse lights (a total of four) have not affected the normal operation of the vehicle.
Purpose of this modification:
Use the cooler 300C
/SRT-8 taillights on the Base, Touring, and Limited models
I have seen two ways that people have approached this modification. There may be more, but here are the two I’ve seen:
1) Just swapping the housings as is – I don’t like this option because it requires that you swap out the old turn signal bulb with a red one. IMHO I think this would look odd from the back when the stop lights and/or the turn signal comes on.
2) Some people have used the method of modifying the FCM (Forward Control
Module) to fake it into believing something different. IMHO this is risky. Why chance frying your FCM or voiding your warranty? Could get pretty costly
IMHO I think the modification described below is simpler and has little to no risk. In addition, the beauty of this modification is that I can return the stock taillights to the car if needed easily.
Base, Touring, and Limited models
(1 to 10, 1=easy) 4
Approx. 2 hours
Cost (for Modification):
approximately $25 or less (assuming you already have the 300C/SRT-8 taillights and wiring harnesses)
Tools and Materials:
Wire cutters, wire strippers or single edge razor blade, black electrical
tape, Dremmel rotary tool with cone point carbide bit, black permanent marker, approximately 3/32” plastic sheet (I used an old dealer flat plastic license plate advertisement), paper and pencil, X-Acct knife, silver paint, epoxy or model glue and soldiering iron.
Step 1: Removal of the wiring harness from the 300C/SRT-8 taillights
On the back of the reverse light socket, mark it with an “R” using the black permanent marker so you can keep track of this socket.
The wiring harness has a plug that is mounted on two pin towers and the pins are melted at the factory to keep the harness plug secure. Using the tip of the carbide bit in the Dremmel tool, remove the excess plastic around the pin in a circular motion. Be careful not to remove too much of the center pin. Only remove enough of the factory melted material to release the plug from the pin. Complete this procedure for both sets of lights and a total of four pins.
Step 2: Isolating the reverse light socket from the main 300C/SRT-8 wiring harness and preparing it for future use
Now that you have the wiring harness in your hands, locate the reverse light socket that you previously marked with an “R”. Using the wire cutters, cut these wires away from the rest of the wire harness where it Y’s into the main harness leaving approximately 4-6" leads on the reverse socket. Remove the black electrical tape from wires.
One wire is black/gray stripe and the other is white/green stripe. Using the wire strippers, strip approximately 3/8” of the insulation off the ends of the reverse wires leads. Complete this procedure for both reverse light sockets. Set aside for future installation.
Step 3: Removal of the Base, Touring, and Limited taillight assemblies
In the trunk, remove each of the stock taillights by removing the 3 large wing nuts. The first wing nut holds the trunk interior in place. The second wing nuts are exposed when you pull the interior away.
Unplug the harness by first sliding the red keeper from side to side and disconnect the fixture from the harness.
Remove the tail light assembly from the fender.
Step 4: Removal of the wiring harness from the Base, Touring, and Limited taillights
This step is similar to Step 1, except you want to mark the three sockets “S” for stoplight (top socket), “R” for reverse light (bottom) and “P” for park light (small side light).
The wiring harness has a plug that is mounted on two pin towers and the pins are melted at the factory to keep them secure. Using the tip of the carbide bit in the Dremmel tool, remove the excess plastic around the pin in a circular motion. Be careful not to remove too much of the center pin. Only remove enough of the factory melted material to release the plug from the pin. Complete this procedure for both sets of lights and a total of four pins.
ok here you have both harnesses freshly removed. I didnt have a dremel to remove the excess around the two buttons to get the harness off so i used a sodering iron and melted the plastic away from the buttons to remove the harness..
Step 5: Modification of the 300C/SRT-8 taillight housings or light bulb sockets
The top socket hole, on the 300C/SRT-8 taillight housing, is for the new stop/turn signal socket from the Base, Touring, and Limited wiring harness and does not require modification. The stop/turn signal socket will turn right into the socket hole.
2 options choose one way:
1: The outside socket hole on the housing that use to receive the 300C/SRT-8 turn signal socket has to be modified in the following way. Using the side of the carbide bit in the Dremmel tool, remove the black section between the two smallest slots to create one big slot. Make sure you maintain a nice radius. Test fit the socket to be sure you’ve removed enough material. You’ll need to clean the plastic shavings out from inside the housing. Air and/or water will accomplish this task. (optional) the tabs on the sockets can be ground down too.
2: modify the actual light socket by grinding down tabs
ok this is an alternative to mikes way of grinding the tailight socket holes. I choose to grind the tabs on the sockets themselves. This is ONLY necessary on the flat grey 90 degree sockets (one on each light harness) since the c tails werent made for two grey sockets. I cant tell you exactly how to grind the tabs because i think it might vary a little bit on each project but just eye ball it up to the hole see why it isnt going in the hole and shave that part off. this is one of mine it only required this little bit to be shaved. The other required more shaving for me because it collided with the female pin socket that goes to the car.
The inside socket hole on the housing that originally received the 300C/SRT-8 reverse light socket will be used as is. No modification is required.
this is optional (picture below shows alternative way):
Lastly, we have to modify the lower socket hole to receive the small “P” park side socket.
Using a piece of paper, locate the small socket hole on the original Base, Touring, and Limited taillight housing and place the paper over the hole and trace its socket shape onto the paper.
Take out your plastic sheet and cut two 1-3/4-diameter slugs from it using scissors or X-Acct knife. Cut the traced shape out of the paper representing the small socket hole. Transfer this shape to the center of the 1-3/4 diameter slug and cut out with the X-Acct knife.
Paint one side of the plastic slug silver to match reflective material inside taillight housing. Apply glue to the bottom socket surface on the housing and center the slug over the socket hole (painted side in effectively reducing the diameter so that the small “P” park light can be plugged in. Allow recommended drying time for the type of glue you used. Repeat on both housings.
This diagram is pretty self explanatory. HOWEVER cutting the 194 socket out in place of the green socket isn't necessary if you want to follows mikes way. i did it to seamlessly (except for a fuse change) to fill all the socket holes on my c tails.
Step 6: Modification of the wiring harness from the Base, Touring, and Limited taillights
Remove the electrical tap from around the wires that lead to the reverse socket all the way up to the Y in the harness. One wire is black/gray stripe and the other is white/green stripe. Approximately in the center of the two wires, remove ¼” of the insulation. Now we’re ready to connect the previously modified reverse socket from the 300C/SRT-8 that we stripped the ends of the wires.
Matching the wire colors, wrap the stripped ends of the wires from the socket from the 300C/SRT-8 around the 1/4” exposed wires on the Base, Touring, and Limited harness. Carefully soldier each wire set together. Wrap soldiered joint with electrical tap.
Here is the new completed harness prior to electrical tape soldered all up. a tap like this could be used instead of soldering
We’re almost there!
Step 7: Mounting the modified wiring harness into the 300C/SRT-8 taillight housings
As mentioned before, the top socket is for the “S” stop light socket, so go ahead and twist it in so that the wires face down (or at about 7 o’clock from vertical).
Next, twist the “R” reverse socket from the main harness into the outside socket with the wires facing up (or at about 2 o’clock from vertical)
Next, twist the reverse socket that was spliced into the wiring harness into the inside socket.
Lastly, twist the small “P” park light into the bottom socket that you glued the new plug into. (if you chose this option)
Step 8: Securing the wiring harness back onto the tower pins
Press the harness plug onto the tower pins so that the pins show through the plug holes. The wiring harness to the small socket on the bottom will lie between the middle of these towers.
Using the soldiering iron again, melt the pins and base material from the plug together at each location to secure the harness plug. Be careful not to melt too much.
Step 9: Installation of the new 300C/SRT-8 taillight housings
Install the tail light assembly into the fender. Secure with two wing nuts. Plug in the harness and secure by sliding the red keeper from side to side. Move the trunk interior back into place. Install the wing nut that holds the trunk interior in place.
Close the trunk and test your turn signals, stop lights, reverse lights and park lights.
UNFORTUNATELY tutorial stops there everything is just plug and play after that. Configuration of new c tail: green socket on bottom black on top greys in the middle the bigger grey obviously goes in the deeper spot.
Lastly when putting the connector back on the the spot we ground or melted the plastic off mine wasnt so clean i just left little pegs to go in the holes. I wanted in nice and secure like they originally were so get some epoxy or some plastic glue and fill in the holes to bind it in place.
OK here is what is going to happen if you follow my part about changing the 194 socket to the green one from the c. When the car goes on your running lamps will go out. THis is because now we are drawing a few more amps and we are blowing the parking lamps fuse # 8 under the hood. this has to be replaced with a mini 20 amp fuse a 15 will continue to blow everytime u put a new one in. I assume 5 more amps is harmless because there are quite a bit of other 20 under the hood but i cant gurantee anything like mike said do at your own risk. But for refernce my setup is flawless.
I dont know if mike mentioned but now you have the blinker brake on the top of the c. a running lamp at the bottom of the c and two reverse in the clear strips (center of the c) tailights. IMO it should have been this way i can actually see when backing up now.
the car is in reverse here and you can see two bulbs lit up totalling (4 bulbs for reverse added visibility)
here is what is going on now in pic
45 leds on the outside luxeon lx3 leds on the inside. i am pretty happy i accomplished what i wanted.