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Trailer Wiring Harness Installation - 2010 Volkswagen Jetta SportWagen

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How to Install a Trailer Wiring Harness on a 2010 Volkswagen Jetta SportWagen


Today on our 2010 Volkswagen Jetta Sportwagen, we'll be installing the upgraded Circuit Protector Modulite with a 4-pole Harness and a Hardwire Kit from Tow Ready, Part Number 119176 KIT. First, we need to remove the interior trim panels behind the driver's side tail light assembly. We'll use the cargo door and then into your trim carpeting flap that we can pull back to access the manufacturer's wiring on the driver's side. Then using our test slide provided with our install kit, we can identify the running, brake and touring signal circuits. To use this tester, we'll take the ground clamp and attach it to a vehicle or body ground and then back probe the manufacturer's wire connector to test the tail light circuit. As you can see the light on the tester will light up when there's electrical current present.

This is identifying the tail lights circuit here on the driver's side that is the white wire with a black tracer. We have already gone ahead and identify the brake circuit, which is a black wire with a red tracer and the turn signal circuit which is a black wire with a white tracer. Well first, we need to remove the rear threshold. In order to do this, we'll remove the rear cargo cover and tray. To remove the rear threshold, there are two fasteners that we need to be removed and then we can easily pry up on the rear threshold releasing the fasteners from the sheet metal.

Next, we'll take the wiring from our converter box and route it behind the tail light assembly on the driver's side. We can use you quick slice connectors to make our connections between the converter box and the manufacturer's wiring. Starting with the brown wire, which is by our running light circuit, connect it with the white wire with the black tracer. Then we'll take the yellow wire, which are our tail light circuit, connect it with the black wire with the white tracer. And our third connection, will be the red wire for our brake light which would be the black wire with a red tracer.

Now, we've got one more connection here on the driver's side to make. We'll take the white wire with the pre-attached ring terminal and ground it directly to the body or sheet metal of the vehicle. Using the self-tapping screw provided with our install kit, here behind the tail light assembly with the sheet metal doubles up, is a perfect location. Now with that attachment made, we'll go back to our converter box taking the green wire, which will be the turn signal circuit for the passenger side and route it over to the passenger side. Remove the interior trim panel, just as we did on the driver's side and route the wire behind the tail light assembly.

To identify the wire which is the green wire with a black tracer and make a connection with the quick splice connector in the same manner we did on the driver's side. With one more connection to make to it, it will be the red wire with the pre-attached yellow-black connector, which will be the power wire for our converter box. Make connection with the black wire after which, drip back the end to make connection with the bud connector. Go ahead and slide the black wire into the yellow bud connector and crimp it down. Quick tech tip: I like to go ahead and wrap this connection with some black electrical tape to secure the two connectors and keep it clean from dirt, debris and moisture. Next, we can take our converter box and run it behind the driver's side tail light assembly. To do this, we'll pull back on the trim panel on the driver's side, near the door pillar and slide it in behind the carpeting and trim panel. Then we'll pull it into position, remove the two-way adhesive and attach it to a clean flat surface. The sheet metal here behind the tail light assembly is a perfect location. Now with our converter box mounted and all our wire connections made, we can re-install the interior trim panels here behind the driver's side tail light assembly. Now, we'll take our black power wire and route it outside the vehicle. To do this, we'll go through our manufacturer's grommet by using our utility knife and cutting a slice into the grommet. We'll feed the grommet from inside to outside pulling the excess wire underneath the vehicle. Next, we'll use several black zip ties to secure the wiring from the ground wire to the green turns in the wire, then we'll cut off the excess our zip tie and re-install the rear threshold, and spare tire and cargo tray. Now, we'll go ahead and take another zip tie and secure the excess of the green wire to the manufacturer's wiring behind the passenger's side tail light assembly. Now, we can go ahead and re-install the trim panel behind the passenger side tail light assembly. Next, we'll get underneath the vehicle and start routing our black power wire to the engine compartment, we'll make connection with the manufacturer's battery. Keep in mind when routing your wire to stay away from excessive heat such as exhaust, our moving component such as steering and suspension. Now, we've got our wire routed up into the engine compartment, we'll go ahead and take one of the black zip ties, and secure it to the manufacturer's wiring. Next, we'll go ahead and route it over to the positive battery terminal, then we'll cut off any excess from the wire as we'll still need to add our fuse holder. To add our fuse holder, we'll simply cut it into half, strip back both ends, adding a ring terminal to one end, and the yellow-black connector to the other, and then attaching it to the black power wire. To secure our ring terminal to the positive battery terminal, we'll go ahead and back off the fastening nut and with this application, the nut is not intended to be removed all the way, but we'll go ahead and loosen it using a pair of side cutters to clip off a small hole into the ring terminal so we can slide it over the positive battery terminal nut post. Now, we can go ahead and re-secure the fastener. We can now go ahead and secure the fuse holder to the manufacturer's wiring, install the fuse in the fuse holder and replace the cap. Next, we'll go ahead and show you how to use your new 4-pole connector. We'll simply open up the rear cargo door, pick up the tray and run the 4-pole out and then down to the hitch or accessory. Be careful to stay away from the latch, as pinching the wire in the latch, can harm it; however, the weather stripping is thick enough that we can go ahead and close the rear cargo door on the wire without harming it. Then once we're finished using our 4-pole connector, we'll simply roll it up and store it down in the spare tire well and that does it for the install of the upgraded Circuit Protector Modulite with a 4-pole Harness and a Hardwire Kit from Tow Ready, Part Number 119176 KIT on our 2010 Volkswagen Jetta Sportwagen.