2008 Hummer H3 Owner's Manual - Page 258

Trailer Brake Control Wiring Harness The trailer brake control wiring harness is located under the instrument panel to the right of the steering column. The wires are taped to the harness that goes to the courtesy light under the instrument panel. The harness will contain the following wires: Trailer Recommendations You must subtract your hitch loads from the Cargo Weight Rating (CWR). CWR is the maximum weight of the load your vehicle can carry. It doesn't include the weight of the people inside, but you can figure about 150 lbs. (68 kg) for each seat. The total cargo load must not be more than your vehicles CWR. Weigh your vehicle with your trailer attached, so that you won't go over the GVWR or GAWR. If you are using a weight-distributing hitch, weigh the vehicle without the spring bars in place. You'll get the best performance if you spread out the weight of your load the right way, and if you choose the correct hitch and trailer brakes. For more information see Towing a Trailer on page 4-50. Red Wire: AUX B+ Black Wire: Ground Light Blue Wire: Brake Signal Dark Blue Wire: Trailer Brakes 4-62