Brake controller hangs

[nwhouston]

I have a P3 on my Chevy truck. Never an issue. Today I found that the controller does not release (go to zero voltage) after I stop. The voltage to the brakes is about 2 volts after I stop. I can tap the brake pedal, and then the controller releases. Tekonsha Help Desk lad says it is the stop light switch on my brake pedal (easy fix according to him).

The controller itself, as well as the brakes, works fine. There are no warnings or flashing lights on the controller face plate during any of this.

Has anyone had this problem, and if so, can share the fix?

Thanks, Larry

[BrucePerens]

P3 is programmed to hold the brakes while stopped. It's in the manual.

[nwhouston]

Bruce, I know the P3 holds a voltage while the brake pedal is engaged (ca. 2 volts with my settings). But the voltage remains when I release the pedal, which it has not done in the past. When I tap the brake pedal then the voltage drops immediately to zero. It is this change that I am trying to understand. Larry

[BrucePerens]

Unplug the controller. Put a voltmeter on the controller connector between the RED wire and ground, and see if anything is making the brake light voltage stay on when you are stopped. It should read around 12 volts or higher when the lights are supposed to be on, and zero when they are not. If you see anything in between or 12V when your foot is not on the brake, there is a problem that isn't in your controller.

Then see if there is voltage between the WHITE ground wire at the brake controller connector and another ground like the one on the cigarette lighter. It should not be as much as a 10th of a volt. If it is really close to zero, change the meter to ohms, and that should be really close to zero as well or you have a ground problem.

If you have dual-filament bulbs, one of them might be shorting the two filaments together or there might be an issue with the sleeve (ground) not making contact. You can take all of the dual-filament tail-light bulbs out to test this, see if it clears the problem, then replace them one at a time until it goes bad. I attached a photo of the 1157 bulb base to show what a dual-filament bulb looks like.

Make sure your brake light switch is working correctly. You can unplug it and use the ohm meter across its two terminals. Also see if the problem goes away when it's unplugged.

[Padgett]

Or even easier, when the 2v is present, see if your brake lights are on. Switch may just need adjustment.

[nwhouston]

Thanks for the tests from both of you. I will investigate. I do know the wiring plug in to the brake light switch is seated correctly, but no testing past that as I am deep in the deflected base right now. Will follow up. I do now know the switch is only $20 even at a Chevy dealer. Not sure how fiddly the change out is but might be doable. Larry

[Padgett]

On my GM cars, the brake switch just screws in/out to adjust. Might just need an adjustment.

[nwhouston]

Padget, are you talking about the single hex head screw that sticks out on the bottom of the switch near the pedal shaft? If that is the one, would I simply move it in or out a 1/4 turn and check the voltage after pedal release? My switch actually moves side to side maybe a 1/2" each way on the pivot point (same place where I can see the screw).

Larry

[Padgett]

I don't know, have never had a pickup truck.

[Shane826]

Your Silverado isn't adjustable, I don't think. Replace only. When you install it, the button self adjusts. It's a one time deal.