2010 Volvo XC90 Tow Wiring and Brake Controller Install

Question

Question:

Tow vehicle is a 2010 Volvo XC90 with Multiplex Wiring. Currently vehicle does not have any factory towing wiring installed. Need to install wiring and brake controller for towing trailer with electric brakes. I plan on using the T-connector wiring harness, part number C56045 to add 4 pole wiring without damaging the vehicle wiring harness. Then connecting the harness to an adapter 4 pole to 7 pole, part number 37185 to obtain the required 7 pole receptacle required by my trailer. Due to the multiplex wiring in my vehicle, installation of a traditional brake controller is not possible. I plan on installing the Tekonsha Prodigy RF brake controller. My questions are as follows: 1 Does this plan make sense? 2 If so, which of the 4 pigtail wires from the 4 pole to seven pole adapter have to be hooked up to power the controller and with what size fuse protection? Is it hooked up directly to the battery? 3 On occasion the trailer is towed with a vehicle that has a brake controller. When this is done, does the vehicle brake controller or prodogy brake controller need to be bypassed?

asked by: Pedro A

1

Helpful Expert Reply:

To install the Tekonsha Prodigy RF Brake Controller # TK94FR brake controller on your 2010 Volvo XC90 and trailer you have established an excellent plan. You are correct in choosing the Tekonsha Prodigy RF Brake Controller for your vehicle that is equipped with multiplex wiring. You will also need a functioning 4-pole trailer connector.

You can install either the Curt T-Connector # 56045 or the Tow-Ready # 118411 to establish a 4-pole wiring connector. To install either of these connectors you will have to access the area behind your rear taillight assemblies and plug the connectors inline to the factory wiring. Then you will have to run a power wire from the converter box to the positive battery terminal.

Once the 4-pole is installed you will then need to use the 4-pole to 7-way adapter, part # C57674. The 4-pole portion of the adapter will plug directly into the 4-pole connector you just installed. Once that is completed, the adapter has four additional wires. The blue wire typically carries the Brake output voltage, but because you are using the RF controller, this circuit will not be needed. Simply tape the end of the wire off and coil it up out of the way. The white wire is grounded to the vehicle frame. The yellow wire is intended for a reverse light circuit, but will not be needed. Tape off the end and coil up out of the way like the blue wire. The black wire provides 12-volt power to the trailer connector to feed the RF unit. Use a butt connector to attach enough 10 gauge wire # 10-1-1 to reach he positive battery terminal. A 40 AMP circuit breaker, part # Pk54540 needs to be installed inline on this circuit.

Now that the 7-way is installed on your Volvo you can proceed to mount and install the Tekonsha wireless brake controller # TK94FR. The optimal position to mount this controller is on the a-frame or tongue portion of your trailer. I have included a photo of the preferred mounting locations for your reference.

You can then proceed to pair the remote brake controller unit to the hand held remote. When doing this please be sure to follow the instructions exactly because the syncing process is very specific for this remote brake controller.

If you are towing this trailer with a vehicle that already has a brake controller installed, then you can bypass the Tekonsha brake controller all together. This is done by plugging the trailer directly into the tow vehicle which bypasses the remote brake controller entirely.

I have included links to the parts listed above, as well as some videos for your reference.

expert reply by: Rachael H

1

Answer 1

I will be happy to help. There are a couple of ways you can add a 7-Way trailer connector to your 2007 Volvo XC90. If you just want the lights to function on the trailer then you can use #37185. Your 4-Way will plug into this adapter and then you…

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Answer 2

The only pin that should be continuously showing 12V power on the 7-Way connector on your vehicle is the 12V power circuit which is normally the black wire but not always. In 7-way wiring the 12V auxiliary power feed is carried on the contact at the…

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Answer 3

The trailer wiring harness part #118411 that you referenced has been confirmed as a fit for your 2007 Volvo XC90 but since it does not wire into the PCM and only plugs in line with the taillight connectors your vehicle would not sense when a trailer…

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Answer 4

I would strongly recommend not using a higher rated fuse to compensate for additional load on the trailer wiring circuit. Those fuse ratings were designed to protect the wiring so that nothing gets fried. Going to a higher rated fuse would just move…

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Answer 5

That's right, the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part #118411 and the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part #C56045 are very similar for the 2005 Volvo XC90. They…

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Answer 6

Yes, the dim lighting on your 2010 Volvo XC90 while using the Curt T-Connector Vehicle Wiring Harness part #C56045 is almost undoubtedly caused by a poor ground. I recommend you choose a new spot on the underside of the vehicle and sand this down…

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Answer 7

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 8

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 9

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 10

The OEM prep package consists of 4 "pucks" in the bed of the truck that will allow you to drop in puck style hitches for easy installation and removal, that gives you a completely clear bed when not in use. The B&W Companion OEM 5th…

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Answer 11

If you just need a 4-pin to 7-pin trailer wiring adapter, then you can use part #C57672. This will plug into the 4-pin trailer connector on your brother's vehicle and give him the 7-pin socket for the trailer. Keep in mind, this will only give…

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Answer 12

You will have to go with a sliding hitch to allow the trailer to make tight turns. For a trailer 8 feet wide the only bed length that's going to allow 90 degree turns without a slider is a stationary hitch. That being said you have two options.…

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