Trailer Wiring Harness Installation - 2010 Volkswagen Jetta SportWagen

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

Today in our 2010 Volkswagen Jetta Sportwagon, we'll be installing our tow-ready T1 vehicle wiring harness with 4-pole flat connector, part number 119179KIT. To begin our install, we'll first go ahead and open up the rear hatch. We remove the rear cargo cover, fold back the cargo lid, and then remove the spare tire cover. With these out of the way, we can remove the rear threshold. To remove the rear threshold, there are two fasteners we'll need to remove first. We'll unscrew the plastic caps and then remove the threshold by gently pulling up on the rear threshold, releasing the fasteners underneath. Now, with that out of the way, we'll move to the driver's side, where we can open up the interior cargo panel on the driver's side. Once we fold the door down out of the way, we can pull back on the carpeting that's been cut out behind the rear tail light, allowing it to fold away and give us access to the driver's side tail light wiring as it goes into the driver's side tail light.

To remove the tail light wiring from the tail light socket, we'll press in the locking tabs at the top and bottom of the connector and remove it. We can then go ahead and cut back any black electrical tape to separate the wires giving us easier access to them, and take out test light provided with our install kit, put the ground clamp on one of the body grounds, and test the wiring to locate our running light circuit which will be the manufacturer's gray wire with a black tracer. That will match up to the brown wire coming from our new tow-ready, 4-pole connector wiring harness and converter box. To connect the two, we'll use a quick-splice connector provided with our install kit. We take the quick-splice connector and feed over the manufacturer's wire, and then take the brown wire from our wiring harness and feed it into the quick-splice connector and crimp it down.

We can then close the clasp. Next, we'll go ahead and repeat the same process for the turn signal circuit here on the driver's side. The turn signal circuit for our 4-pole wiring harness will be the yellow wire from our tow-ready wiring harness. On the vehicle side, it will be a black wire with a white tracer. Once again, we'll use a quick-splice connector to secure the two. Next here on the driver's side, we'll need to connect to the vehicle's braking circuit. That'll be a black wire with a red tracer, and be a red wire coming from our new wiring harness.

Now, once we've made the connection with these three circuits, we'll go ahead and wrap it up with some black electrical tape to help keep our connection points clean and free of dirt, dust, debris, or moisture. Next, we'll take the white wire with the pre-attached ring terminal coming from our converter box. This will be the ground wire for our converter box and 4-pole harness. Using a self-tapping screw, we'll go ahead and secure it to the body or sheet metal of the vehicle. Note, it's a good idea to find a location where the sheet metal doubles up for a good, secure ground. Next, we'll take the green wire coming from our new wiring harness, and feed it over to the passenger's side.

We'll repeat the same process for the turn signal circuit on the passenger's side. To assist in routing our wire, we'll use a pull wire which can be a stiff piece of wire, or in this case, a piece or air tubing, to help route behind the interior paneling. Once we get over the passenger's side, we'll go ahead and remove the carpeting cut-out behind the passenger's side taillight assembly and set it aside, and then route our wire behind the interior paneling. Now we've got our green wire over on the passenger's side, we'll go ahead and repeat the same process of locating the passenger's side turning signal circuit by removing the wiring harness from the taillight assembly, and probing the wires while the turn signal circuit is on. All right. After checking, we know it'll be a black wire with a green tracer. Same quick-splice connector to connect the wire from our tow-ready wiring harness to the black wire with the green tracer on the vehicle side. Once again, once this connection's made, we'll go and wrap it up with some black electrical tape. With that done, we're now ready to route the power wire for our converter box. The power wire will go from our converter box, and ultimately up to the vehicle's battery. We need to route the wire through one of the manufacturer's assisting grommets here in the lower wheel well. Using a utility knife, we can go ahead and cut a small slice into the grommet to feed our wire through. To assist in feeding our wire, we'll use a pull wire, run it through the grommet, connect our power wire, and then pull the power wire through the grommet. Once we have the power wire pulled into position with the converter box, we can go and strip back the power wire end and add a yellow butt connector. We'll then take the red power wire from our converter box, and secure it to the other side of the butt connector. We'll go ahead and wrap this connection point up with some black electrical tape. Now with all our connections made, we're ready to secure the converter box. Using a two-way adhesive provided with our install kit, we'll go ahead and peel back one side and adhere it to the converter box, and then peel back the other side and adhere the converter box below the driver's side taillight assembly, locating a flat, clean surface. Now with that done, we'll go ahead and secure the wiring that runs underneath the threshold, which will be our green turn signal circuit, and the black power wire. To assist, we'll use a loom clamp, part number A0250, and a self-tapping screw. Now with that done, we're ready to reinstall our interior trim components. Next, we'll get underneath the vehicle and start running our power wire up to the front. Keep in mind, when routing a wire, stay away from any moving components, either steering or suspension, or excessive heat such as exhaust. Some applications as this one, it'll also be necessary to use the loom clamp to secure our wiring as necessary. Once we get up to the front of the vehicle, we'll use our pull wire to assist in routing through the engine compartment and up to the battery. Now we've got our power wire routed up to the battery, we'll go ahead and cut off any excess to the power wire and strip it back. We'll then go ahead and prepare our in-line fuse holders provided with our install kit. We'll cut the fuse holder in half and strip back both sides, adding a butt connector to one side and a ring terminal to the other. We can then take that butt connector and secure it to our power wire we ran from the rear of the vehicle. Next, we'll go ahead and secure the ring terminal to the positive battery post. After this application, the ring terminal stud is not designed to be removed completely. Go ahead and cut a small slice in the ring terminal, fit it over the stud, and then re-secure it. Once we've done that, we'll go ahead and secure our wiring with the black zip tie provided with our install kit, and then we can install our fuse into the fuse holder. With that, we'll go ahead and put the fuse holder cap on, cut off any excess from the zip ties to clean up our install look, and we're ready to hit the road. Next, we'll go and test our new 4-pole connector. Take the 4-pole connector out and use our test light to test the 4-pole connector by putting a ground clamp on the white wire, or open or bare terminal. Then, testing the brown wire terminal will be our running light circuit, the yellow wire terminal will be the left turn signal left brake, and then the green wire terminal will be the right turn signal, right braking. Now we know our 4-pole connector works, let's go ahead and show you how to use it. We'll simply open up the interior trim panel and run our 4-pole connector towards the center of the vehicle and down to the hitcher accessory. Be careful to stay away from the latch, as pinching the wire off in the latch can harm it. However, the weather stripping is thick enough that we simply close the 4-pole wire on it, pull out what's necessary to run to our hitch accessory. Then once we're finished, we can simply roll it up and store it in the interior of the compartment. And with that, this will complete the install of our tow-ready, 4-pole wiring install kit, part number 119179KIT on our 2010 Volkswagen Jetta Sportwagon. .