ModuLite Ultra Protector Wiring Harness w/ Integrated Circuit and Overload Protection

Video Transcript for Traile Wiring Harness Installation - 2010 Mercedes-Benz-GL-Class

Today on our 2010 Mercedes GL450, we'll be installing the Tow Ready ModuLite wiring harness with trailer pigtail, part number 119192. To begin our install, we'll first remove the driver and passenger side interior trim panels. Here on the passenger side, we'll simply turn the securing knob, unlocking it, pulling the panel out, and setting it aside. On driver side, we'll turn the knob, remove the door, then we'll need to remove the interior compartment. To do this we'll unlock both fasteners and then pull up and out on the box at the same time releasing it from any other points that secure it. Now on both sides, we can gain access to the manufacturers taillight wiring. Next, we'll need to test the wiring so that we can locate the circuits for our running lights, brake signal, and turn signals as this is considered a 3-wire taillight system where each circuit is independent from each other. To test out lights, we're going to go ahead and remove the connector from the back of the housing.

Now, we have access tot he taillight wiring connector, we'll use the test light to locate the correct circuit for each wire. Here on the driver side, we've located the olive wire with the black tracer will be the running light circuit, the red wire will be the brake circuit, and the black wire will be our left turn signal circuit. Here on the passenger, we'll use the manufacturers green wire with a black tracer. Now, we'll move back over to the driver side and start making our connections. It can be a little easier to make the connections if we remove some of the manufacturers tape and pull the wire loom apart. Now, we can go ahead and slide on the quick splice connector provided with the install kit and the follow it up with the wiring coming from our new Tow Ready harness.

Once the wire is in place, we'll crimp it down and close the clasp. We'll go ahead and repeat the process for our brake and turn signal circuit. Now, with our driver side connected, we can go ahead and take some black electrical tape and re-wrap the wiring harness. This will help to keep the wires together and wrap up our connection points to keep out any dust, dirt, debris, or moisture. Once we have the wires taped up, we'll go ahead and re-install the connector back into the taillight socket. At this point, we'll need to remove the rear threshold.

To remove the rear threshold, there are 2 fasteners that will need to be removed. These are T30 Torx bit screws. Once removed, we can then get underneath the threshold with a interior trim panel tool or a flat blade screwdriver and release the fasteners underneath the threshold. Once we have it popped free, we'll go ahead and turn it over and show you the fasteners. Now, we'll go ahead and set that aside.

Take the green wire and run it from behind the interior trim panels on the driver side, underneath the threshold, and over to the passenger side. Here, we'll go ahead and make the same connection as we did earlier by removing the manufacturers tape, installing the quick splice connector, and then our Tow Ready harness wiring. We'll crimp it down and close the clasp. We'll re-tape the wires and then re-install the connector back into the socket. We'll leave our power wire over here this time as we'll cut off the excess later. Next, we'll take out white wire with the pre-attached ring terminal, which will be the ground wire for our module box, and attach it to the body of the vehicle using a self-tapping screw provided with our install kit. Now, we'll take out trailer wiring and feed it down underneath the vehicle. To do that we're going to go through one of the manufacturer's grommets here on the driver side. We'll go ahead and remove the grommet from the interior side panel, cut off one of the nipples of the grommet, and then feed the wire through the grommet. Once we feed the wire through, I'm going to go ahead and wrap up the wiring with some black electrical tape to help hold it together and protect it as it will be routed underneath the vehicle. We'll go ahead and feed it through the hole and then re-install the grommet. Next, we'll move underneath the vehicle and route the wire over to the center of the vehicle and down to the hitch. Now that we have our wire to the hitch, on this application, we'll be installing the Hopkins adapter 4-pole to 7-pole and 4-pole, part number 37185. To secure it to the vehicle, we'll be using the DrawTite mounting bracket for 7-way, part number 18138, and the DrawTite no-drill mounting bracket, part number 18136. To start, we'll take our 7-way connector and secure the 7-way mounting bracket to it using the hardware provided. Next, we'll go ahead and mount the 7-way bracket onto the no-drill mounting bracket. Now, before I install the bracket onto the vehicle, I'm going to go ahead and start wrapping up the wires with some black electrical tape. Once again, this will help to bundle up our wires and protect it from any of the outside elements. Note on this vehicle, we'll not be using the purple wire, which is for reverse taillights. The purple wire, we're going to go ahead and cut short. We'll go ahead and feed them through the hole in the bracket and install the bracket onto the vehicle. To secure the bracket to the vehicle, we'll use a worm-gear clamp provided with our no-drill mounting bracket. Now, with our 7-pole bracket secured to the hitch, we'll go ahead and start connecting our wires, stripping back both ends and adding the butt connectors in between. For this application, we'll be matching color for color. Once we've made all our connections, we can go ahead and wrap up the rest of our wires with some black electrical tape making sure to double up over the butt connectors to help prevent any dirt, dust, debris, or moisture from causing corrosion in these contacts. With that done, we'll need to secure the wiring up underneath the vehicle, keeping in mind when you route your wires, you want to stay away from any moving components, such as steering or suspension, or excessive heat such as exhaust. We'll run the wire up to the body lip. For this application, we'll be using a red line metal loom clamp, part number A0250, and a self-tapping screw. Once secured, we'll pull the excess wire back over underneath the driver side taillight assembly and then back up into the vehicle. Now, we'll move back to the driver side quarter panel. Here, we'll need to mount the converter box securing it to the manufacturer's wiring with a long black zip tie and then secure any of the wiring necessary to keep it bundles and out of the way. We'll cut off the excess of the zip tie to clean up our install look and then re-install the interior pocket and cargo panel. Next, we'll need to secure the wiring as it runs underneath the threshold over to the passenger side. To do this, I'm going to use a couple pieces of black electrical tape. This will be a temporary hold until the threshold is back in place. Then, we'll go ahead and re-install the rear threshold. Next, we'll move over the passenger side interior trim panel where we'll cut off the excess from our power wire. Next, we'll go ahead and prepare the fuse holder. To prepare the fuse holder, we'll cut it in half and strip back both ends. We'll add a ring terminal to one side and a yellow butt connector to the other. Next. We'll go ahead and strip back our power wire and then secure it to the yellow butt connector making our fuse holder inline with the power wire. Once we do that, we can once again go ahead and wrap up this connection point with some black electrical tape. Now, we'll go ahead and remove the nut from the positive battery post here in the fuse panel at the rear of the vehicle. Note that this application is not intended to come off completely, so we'll go ahead and back it off partially, and then, we'll use a pair of side cutters to cut a small slice into the ring terminal and fit it over the positive battery terminal stud. Then, we can re-secure the nut securing the ring terminal to the stud. With that done, we'll go ahead and install the fuse into the fuse holder and install the fuse holder cap. With that, that will complete the install. Next, we'll go ahead and show you how to test the new 4-pole connector. We'll simply take out test light and hook the ground clamp to the negative terminal. Then, using our test light, we'll test each point of our 4-flat connector, testing each one the other 3 terminals with the corresponding indicator starting next to the ground terminal will be the running light, then the left turn signal, left brake, and the right turning signal and brake. This will complete the install of our Tow Ready ModuLite wiring harness, part number 119192, on our 2010 Mercedes GL450. .