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Base Plate Wiring Harness Installation - 2003 Cadillac CTS

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How to Install a Base Plate Wiring Harness on a 2003 Cadillac CTS


Today on this 2003 Cadillac CTS, were going to install part number TD10000 from Tow Daddy, their plug and tow universal kit. First thing we need to do is access the wiring harness and were going to remove the interior panels to get to the wire harness for the tail lights of the car. Well move the fasteners for the threshold and well also remove the fasteners for the carpeting on the inside and pull it out of the way. Well do this on both sides of the vehicle. Now, well go ahead and peel back interior carpeting so we can get access to the wires. This bundle of wires is what goes to the tail lights, so well look for our signals here.

First off, were going to go ahead and start looking for the running light circuit. It looks the running light circuit on the vehicle is going to be a four-pole wire. Well cut back of electrical tape and go down the wire a little bit and then well cut in half and add our butt connector. Part of the wire that goes to the tail light, and then well connect the brown wire with a stripe on it, well connect those two together. The other half of wire that we cut from to the vehicle, were going to connect it to the brown wire coming out of the wiring harness and that brown wire will be an all solid color.

Now, well go ahead and look for the right turn signal. On the vehicle, we determined that it was blue with white stripe. Our green wire with stripe will go to the tail light. The other half of the wire will go to green which is all solid. It looks like the all-white wire will be our brake signal, so well cut that in half; and well attach the lead going to the tail light.

Well connect that to the red wire with the stripe on it, and then the solid red wire will connect to the other half of the wire harness going back to the white wire. Now, our wire connections are finished for the passenger side, now well go over to the driver side and basically repeat the same steps over there. After inspecting the drivers side, we found out that the purple wire is the running light circuit. The wire going to the tail light will get the brown wire with the stripe. Then, the other half of the wire that goes to the tail light will go to the solid brown wire.

Well go ahead and turn on the left turn signal, and that looks like again the blue wire with a white stripe. Well go ahead and cut that in half, and apart going to tail light will get the yellow wire with the stripe and the other half of wire, well get the solid yellow wire. Now, well go ahead and look for the brake signal, and it looks like once again its going to be the white wire, so well cut that in half. The wire going to the tail light, well get the red wire with a stripe. Then, the other half of the wire will get connected to the solid red wire. Now, we can go ahead and connect our white wire. Well connect a ring terminal to it and well hook it up to the factory ground located on the driver side. With all our wires hooked up on the drivers side, well go ahead and tuck our paneling back into place for now. Make sure our wirings are at the way we want it. Next, well go ahead and mount up the module box. Well clean up a part of a sheet metal on the inside. Now, were going to take our wire harness and hook it up to the module box and well go ahead and adhere it to the sheet metal. Now, well go ahead and take the wire of the four-pole end, running that back to the passenger side, underneath the carpet, and youll locate a grommet right here that will loosen up and put a slot into it. Run the wires through and well install the grommet. With that done, well zip-tie our wires up to keep everything nice and neat. With the wires run through, well go ahead and reinstall the interior components of the carpeting and the trim. After that well pull it through at the bottom of the car and well run it up to the front. When we run it up to the front of the vehicle, we want to make sure that we stay away from anything moving like the suspension components or anything thats hot like the exhaust. We can go ahead and run the wire to the center of the baseplate and well go ahead and tie it up there. Now, Ill go ahead and show you how the lights work on the vehicle. As noted, in the instructions, it says, that the separate brake and turn lights will light together when connected to a towing vehicle. With that, thatll finish it for our install of part number TD10000 from Tow Daddy on our 2003 Cadillac CTS.