Wednesday, June 15, 2016

Brake control installation

Electronic brake controls are necessary for trailer towing, and installing these gadgets is a simple process requiring the use of hand tools such as electric drill motor, screwdriver and wire strippers. Brake control installation should consider accessibility for manual activation.

Electronic units, which are used almost exclusively for trailer towing, are easy to mount and wire


While special cooling systems, alternators, batteries, wiring harnesses and even hitch receivers are offered as options on tow vehicles, brake controls are almost universally not part of the option list. If you are going to tow a trailer or fifth-wheel with electric brakes, then a brake control must be installed.

Over the years - and especially now that anti-lock braking is so prevalent - electronic controllers have become the norm. The installation process is not very complicated, and, as a matter of fact, the project can be completed using only basic hand tools such as an electric drill motor, screwdriver and wire strippers/crimpers. A volt/ohmmeter is also handy if you need to do some investigation to locate the brake switch wire, and for checking the finished circuit.

The controller shown in these photos is a Kelsey model 81741A, an intertia-activated all-electronic model. The procedures for installing most other electronic brake controllers, including time-actuated models that don't have inertia sensors, are very similar, and most controllers use the same wire color code. Each brake controller comes with a complete set of factory instructions, and, if in doubt, a factory technical helpline is usually available as well.


The rules for mounting the brake control are fairly simple. First, it must be readily accessible to the driver, so it can be reached in a hurry for an emergency manual brake activation, which is a valuable technique of combatting trailer sway. Second. it should be out of the way so the driver's knees or feet don't bang into it when entering or exiting the vehicle, or while the driver is in the driving position. Third, if it's an inertia-activated controller, it should be as close to level as reasonably possible or within the manufacturer's recommended off-level range, and, finally, the location should be as aesthetically pleasing as possible.
Most brake controls are installed low on the dash, just to the right or left of the steering column. Choose a spot based on your own preference, giving special priority to which hand you'd use to grab for the manual control in an emergency.

Caution: Before drilling any holes, check to make sure there are no wires that you'll drill into on the back side of the dash. You may need to temporarily move some wires while drilling, and, if using sheet-metal screws, protect the wires from abrasion once they're back in place, if they rest against the screws.

The bracket is installed on the dash using the factory-supplied hardware. Ideally, there should be some type of metal backer behind the dashboard material to which the bracket is fastened. If not, the bracket can be screwed to the plastic part of the dash, and be sure to use the washers or metal backing clips, if included in the hardware kit. Sheet-metal screws used without reinforcement can pull out easily from a plastic dash.
Next, the brake control is mounted in the bracket and adjusted for the most convenient location. Some controllers have a pair of screws per side, which makes it pretty easy to lock them in place. Others have a single screw per side, in which case you need to snug the screws down pretty good to keep the controller from tipping, which can throw off your pendulum adjustment, if so equipped.


Most brake controls use a standardized wire color code, which is as follows:

* Black: 12-volt DC power (positive) line
* White: Gound, or 12-volt DC negative
* Red: Brake switch activation line
* Blue: Trailer brake power line

If you have a new or late-model Ford or Dodge truck with the factory-supplied brake control plug and pigtail, all you need to do is connect the brake control wires to the proper factory pigtail wires, plug it in, tuck the wires safely away and you're ready. For GM vehicles and others without the factory wiring, you need to do some electrical exploration to make the appropriate connections.

Caution: When working on a late-model vehicle equipped with an airbag, be sure to first locate and identify the airbag wiring under the dash. Most manufacturers have these wires bundled in a bright yellow sheath with bright yellow plug connectors. Once located, DO NOT do any probing of, or connecting to, these wires! The airbag could accidentally inflate and it could kick you around like a rented mule. Most manufacturers of brake controls provide very detailed information for locating the proper wires for connection.

Make sure you have a generous supply of crimp-on terminals on hand before you begin this project. It's always better to fasten the wire using a crimp-on terminal rather than simply twisting the wire around the screw or bolt.

The black 12-volt DC power line is best connected directly to the battery's positive terminal. A 20-amp circuit breaker (some brake controllers, such as the Tekonsha Voyager XP that is designed for a six-brake trailer, call for a 30-amp circuit breaker; use your brake control instructions as a guide) must be wired into the line as close to the battery as practical. This is the best way to avoid burning wires in the event of a short. And once the location of your 12-volt DC power source is determined, set up the wiring, but don't make the actual connection until the last thing. This avoids working with a system that's already "hot" until all the connections are made.

The white ground line should be connected directly to the battery's negative terminal. Don't use an underdash bracket, since many of them are insulated from the vehicle's body ground. Take the ground wire directly to the battery, or at the very least, a major steel body member or designated vehicle ground point.
The red wire is connected to the non-powered wire of the brake light switch. When the brake pedal is depressed, the non-powered side of the switch receives 12-volt DC power for the taillights and thus, activates the brake control.

Finding this "cold" side wire may be the toughest part of the installation project. The wire is clearly marked on some vehicles, but on others, you'll need to do some spelunking. A read-through of the service manual for the vehicle may reveal the wire's location, or a visit to your dealer or RV shop for some words of advice from a technician could likewise help you find the wire. The Tekonsha instruction booklet has a complete list of the wire color codes for the big-three auto manufacturers, but others simply direct the user to locate the wire and connect the red brake control line to it.

Each vehicle will have a different brake wire location. At best, you can find the brake switch, located somewhere near the brake pedal assembly. Use a multimeter or test light to locate and verify the "cold" brake switch line. Connect one side of the tester to ground, and the other to the wire in question. The wire should receive power when the brake pedal is pushed. Once located, the brake control line can be spliced to the wire using a quick connector. Do not cut the brake switch wire.

The blue wire is connected to the trailer brake power line that runs back to the trailer plug. Once again, most vehicles are different as far as where the blue wire is located. For example, '94 and '95 Dodges don't have the complete brake control pigtail, but the light blue trailer brake wire is tucked away under the dash, behind the 84-pin connector, and is labeled "Trailer Tow." Both GM and Ford will likewise have the blue trailer brake wire similarly located.

Test your installation before plugging the trailer into the receptacle. Have a helper apply the brakes while you use your multimeter or test light to check the proper pin for power. The trailer brake pin in a standard 7-pin Bargman-style receptacle is at about the five o'clock position (lower right). The blue wire is connected to the marked no. 2 position inside the receptacle. That pin should be powered up when the brake pedal is pressed. The Tekonsha Voyager only works when the trailer is plugged in, so you'll need to skip the terminal test, plug the trailer in and see if the brakes are applied that way.

Once the system is verified and tested, you're ready to hitch up your trailer and adjust the brake control per the factory instructions. Installing the brake control is a job that takes some care and thoughtful assembly work, but it's well within the means of most RV home mechanics.