Trailer Brakes Locking up on a 2000 Chevrolet Suburban When Fuse is Installed Under Hood  

Question:

Expert Reply:

If the lights are working correctly on the trailer, then the brake feed wire and power feed wire could be switched on the vehicle side. You would just need to switch these two wires inside the connector. I would use a circuit tester, item # 4PTW2993, to check this first. Since the trailer brakes are working correctly on another vehicle you can test the connectors on each vehicle and see if they are wired the same.

If it is not the trailer connector, it sounds to me like you have the power wire from the post that is powered through the 40 amp fuse connected to the brake feed wire that runs to the brake controller. When you find the wires under the hood next to the fuse block there should be a red and a blue wire. The red wire should be connected to the post that is powered through the 40 amp fuse and is the power wire to the brake controller. The blue wire should be ran to the trailer connectors brake feed connection at the rear of the vehicle. If the blue wire is connected to one of the posts under the hood you will have constant power to the trailer brakes and they will lock up when the fuse is installed. Both of these wires may need to be switched if the brake controller has no power. We have an article about brake controller installation on the Chevrolet/GMC pickups, 1999-2006, for you to review (see link). Another possibility is that your trailer connector is wired differently than the connector on your vehicle. If the lights are working correctly on the trailer then the brake feed wire and power feed wire could be switched on the vehicle side. You would just need to switch these two wires inside the connector. I would use a circuit tester, item # 3808, to check this first.

Your suburban uses a Universal Brake Control Wiring Adapter 1999 - 2002 Chevrolet, GMC, Cadillac, item # 20263, which should have the red wire in the top left corner looking at the connection side of the connector, with the locking tab in the down position. If your red wire is in the bottom right position then you will need to move it to the top left position by removing the blue locking clip and pressing on a very small locking tab on the connection side of the terminal,with a small screwdriver to remove the wire and install it into the correct port on the connector.

The other wire positions in the connector are as follows, looking at the connection side of the connector with the locking tab down. The blue wire should be in the bottom left position, the black wire should be in the center left position and the white wire should be in the top right position. If the blue and black wire have been switched then this could also be the reason for the trailer brakes locking up when the fuse is installed under the hood.

expert reply by: Robert G

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