Fuse Position to Activate Accessory Power and Brake Control Power on a 2008 Chevy Avalanche

Updated 09/29/2011 | Published 09/28/2011

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Question:

Can you define the actual fuse positions in the fuse box that activiate the accessory power and brake control power on 2008 Avalanche. I have installed my Prodigy brake controller per the instructions on your site and although my brake controller has power, when I connect to my trailer I get no signal to the trailer brakes. When I actvate the manual brake lever on the prodigy, I get the NC in display No connection even though I am plugged into the trailer.

asked by: David

Expert Reply:

If my memory serves me right the fuse positions for the auxiliary power posts under the dash on a 2008 Chevrolet truck or SUV are the closest two square fuse slots in the front end of the power distribution box, see photo link. The best way to test those power posts is to use a circuit tester, item # PTW2993, if needed. Ground the lead from the tester and touch each power post independently. If the tester lights, then the fuse is in the proper location. If not, a square fuse should be inserted. Once the fuse is installed in the correct slot the stud will be hot.

The fuse box lid normally has a legend underneath it stating the proper fuse location and size. This should help you out also.

Since you say that you have power to the brake controller, it sounds like the fuse is in place. If this is the case there are several things you will need to check. The N.C. reading indicates that the brake controller is not sensing a connection to the trailer brake magnets.

Start with checking the truck and trailer connector. Open them up and look inside the connectors. If you find a loose wire shorting to the trailer brake feed or corrosion inside the connector, this could be the issue. Fix any mis-wiring, see link to trailer connector diagrams, and clean out the connectors if any corrosion is found. Some dielectric grease, # 11755, will help prevent corrosion and would be a good idea to use on the connections while you have the connector open. If you determine that you need a new connector, the Pollack 7-Way RV connector, # PK11916, would most likely be the correct choice for your truck. For the trailer the Pollack 7-Way RV connector, # PK12706, would most likely be correct.

Next, check the ground wire for the brake controller, at the trailer tongue, and at the back of the vehicle and make sure they are grounded properly to a clean rust, paint and primer free portion of the vehicle and/or trailer frame. Also, make sure one wire from each brake magnet is grounded properly either to the ground wire from the trailer connector or to the trailer frame.

Next, check the brake feed power wire to be sure there is not an open circuit on this wire. Check all the way back to the brake magnet connections. If the wire is pinched frayed or broken and contacting the trailer frame or another wire, correct any of these issues.

You should find the issue using these troubleshooting measures.