Brake Lights Stay On, 08 1500

[Ol'Jim]

All I have is my phone, and the Search This Forum link doesn't work, so apologies in advance if there is existing info on the problem. My son's 08 1500 2WD truck has had problems with the cruise control not working correctly. Think I found out why, was following him today, and his brake lights came on. He was on an open road, no traffic, so I called him and asked if he was riding the brake with his left foot. He said No. Told him what I saw, and when he came to a red light, I told him to stab the brake 2 or 3 times, then let up. No change, brake lights stayed lit. He pulled into a lot, and unplugged the connector on the brake pedal arm. Then he turned on the key, brake lights were still on. Connector has 4 wires, I guessed one circuit for brake lights, one for cruise? Or is one for the transmission interlock solenoid that prevents shifting out of Park until you press the brake pedal?
Getting ready to go check things with a voltmeter.
As always, any advice will be appreciated.
-Jim.

[phipps]

Sounds like brake switch is bad.

[Ol'Jim]

That is what I was thinking, but with the connector unplugged, switch would not be part of the circuit, right? Hopefully it isn't a short in the wiring. I need to get hold of a wiring diagram.

[phipps]

Originally Posted by Ol'Jim

That is what I was thinking, but with the connector unplugged, switch would not be part of the circuit, right? .

You would think that, but I think pretty much everything is actually controlled by the computer these days. It uses inputs from various sensors and switches to determine whether the lights should be on or off. It's possible the default for an open circuit is "lights on".

I'm not an automotive engineer so that's a stab in the dark.

Good luck tracking it down!

[j cAT]

Originally Posted by Ol'Jim

That is what I was thinking, but with the connector unplugged, switch would not be part of the circuit, right? Hopefully it isn't a short in the wiring. I need to get hold of a wiring diagram.

the brake switch has many switches. abs/brake lights/PCM controls.

2 things can cause this , the brake pedal does not go up all the way or the switch contacts are worn out.

BOTH THESE PROBLEMS HAVE BEEN REPORTED.

UNPLUGGING THE SWITCH IS NOT A WAY TO CHECK OPERATION.

[777stickman]

With the issue you're having, no cruise control, brake lights always on. As j_cAT mentioned the brake pedal may not be returning to a position to turn the brake lights off which would cause the cruise control to not work.

Simple check: With your foot/toe pull up on the brake pedal. If the brake lights go out you have an adjustment issue. If they don't go out you have a switch/wiring issue.

[Ol'Jim]

You fellas were right on the money, as always.
It was a faulty brake switch, the contact button was stuck in the depressed position. My son had replaced it about a year ago, (very disappointed in Borg Warner, he paid a buck extra for this crappy chinese junk). This time he opted for the $1 less AC Delco part. Problem solved. Hope it lasts even half as long as the original, which went 100K miles...
Thanks Guys!