How to Wire a Trailer Brake

Electrical Info

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My Flasher doesn't work or flashes fast

You need a heavy duty flasher to handle the load of the extra lights. Go to any auto parts store and get a 2 pin variable load flasher. If you want to go electronic get a Tridon flasher.

Hooking up an Electronic Brake Controller

On some model year Hummers it is necessary to swap two wires at the rear trailer connector (apparently it was mis-wired at the factory) I know this applies to the 95s and may apply to other years as well. The two wires that are reversed are the purple and dark blue. Purple is Aux (that wire you connected under the hood) and dark blue is the Brake control. If you don't switch these two wires your trailer brakes will apply all the time.

This controller was recommended to me. I haven't used it myself. Prodigy 90185 by Tekonsha available with a wiring harness for most common vehicles, mostly plug and play.

If you're going to be hauling really heavy loads like pulling a trailer with a Hummer get a good weight distribution hitch (500.00). Don't worry about sway unless you are getting an enclosed trailer. A good sway unit is a Reese Dual Cam (under 200.00).

AMG provides a number of accessory connectors under the dash. Some are switched with the ignition and some are always hot. These wires are located loose in front of the fuse box on my 98. The wires usually have silver labels.

The newer trucks like the 2000 have a block on the fuse box instead of loose wires with the accessory connectors.

Trailer brake wires are also located here.

The left arrows point to the labels, the right arrows point to the shrink tubing on the wire ends.


The hummer has 3 wires you need under dash.
Blue (brake wire)
Yellow(power wire)
Red(stop wire)
connect these up directly to your brake controller. My brake controller had the following wires for hookup.

Red (stop wire)
Black (power wire)
Blue (brake wire)
White (ground wire)

I used a bolt for the door hinge strap for the ground. Make sure you scrape all the paint off of the bolt for a good ground. Before connecting everything up make sure your power wire is always hot using your new ground point.

There is another electircal connector under the hood with a ring connector that needs to be attached to a power source. On my 98 the wire can be found on the drivers side near the power block around the cti compressor.

The body harness that goes to the rear has this connector which plugs into the rear of the 6 blade trailer plug. Even though it's sealed in heat shrink tubing you can see that it still corroded.

An adapter from the ford 6 blade trailer plug to a standard 4 pin one.

Draw Tight Products 18143 Some of these are readily available at Walmart/ Meiger.