Prodigy P3 Brake Controller on 2008 Chevy Silverado Putting Out Voltage w/ No Trailer Plugged In

Question:

I just installed the P3 on a 2008 Chevy Silverado. It had the wiring already in place and I used the directions from the video on your website. Everything seems to work fine as I get the no trailer warning at start-up. However, when I drive it appears the controller is sending voltage based on the display even though no trailer is attached,. It also shows a low voltage fluctuation at times when driving and not applying the brakes. The manual leads me to believe this should not be happening when no trailer is attached and the controller screen should not be showing voltage. I do not have access to a trailer with brakes yet so I cant test actual operation. Thanks.

asked by: David W

Expert Reply:

The Tekonsha P3 is designed to send back a test current frequently to 'look' for a trailer, but this is just a tiny amount of voltage, about 1-2 volts. Since yours seems to be sending back more voltage than that, a more likely issue is that your truck has a bad brake light switch, which is common on 2008-2013 Silverado/GMC Sierra models. Is your cruise control working? If it isn't, you've positively confirmed that the brake lamp switch is bad. I've confirmed this with Tekonsha's technical service department.

expert reply by: Mike L