Adding a 7-Way Trailer Connector and Brake Controller on a 2008 Toyota Tundra with 4-Way Connector


bought plug andcontroller I install it very easy ,but were is the blue brake wire ,got a 4 wire plug on the hitch,can I splice it at the white plug please email me


Expert Reply:

It sounds like your 2008 Toyota Tundra has a factory 4-Way trailer connector. A 4-way only has the basic light functions for a trailer. If the trailer also only has a 4-Way then it also has no wiring to the electric brakes.

On the Tundra, to install a functioning 7-Way and brake controller you will actually need to use 4 to 7-Way adapter # 37185. Your factory 4-Way will plug into the back of this unit. You will then need to hardwire the remaining wires. The white wire needs to be grounded to the vehicle frame. The purple or yellow wire can be connected to a reverse light circuit behind one of the taillights (if your trailer does not have reverse light, this wire can be stowed out of the way).

You will then need to use Jacketed 2-Wire, # 10-2-1. You will need a long enough piece to reach the front of the truck. I would say 20 feet would suffice. It is sold in 1 foot increments so enter 20 in the quantity box. You will attach the black wire on the harness to the black wire in this duplex cable. Attach the blue wire on the harness to the white wire on the cable.

Route the cable under the truck, avoiding areas that may pinch or burn the wire, up through the engine compartment near the battery. Under the hood, separate the two wires in the cable. Attach the black wire first to a 40 amp circuit breaker, # PK54540, then from there to the positive battery terminal.

Route the white wire through the firewall over to the brake controller. On the harness from the brake controller to the port on the truck, gain access to the blue wire. Sever the blue wire and attach it to the white wire you ran through the firewall. So now, the blue wire from the brake controller goes to the white wire and back to the 7-Way. With these connections, installation will be complete. I have included an FAQ article that should help.

You may also need some butt connectors, # 05732-2 and ring terminals, # DW05705-1,

expert reply by:
Michael H

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