Idiot brake light on when freezing temp outside

[markelectric]

94 k1500 ext cab 4x4 pu. I have a break warning light that comes on with the key as normal, goes out while starting, and then comes on a second or two after the engine is running and stays on untill the truck is shut off. My usual drive to work is about 15 min. I can shut it off and restart it with the light staying off after the engine restarts. I tried messing with the parking brake pedal and noticed the light getting brighter when the pedal is depressed, and dims a bit when pedal is released. Never have felt any difference in the driveing or brakeing. Never see the light act up if it is above freezing. My mechanic buddy has flushed the brake fluid late last spring as this was happening then but could feel brakes grabbing each revolution of the rear wheels. At that time we found the parking brake cables rusted. They were replaced and never had another problem, but thinking back, I dont think it ever froze after that.
Any thoughts?

[catmandoo]

mine will come on at will,might stay on for 50 miles then go out and won't see it again for 2 days then it might come on and stay on all day,the wierdest thing about my brakes though ,is on occasion say i'm setting at a stoplite holding the pedal,i will hear a little click and can feel the pedal pulsate,and if i press alittle harder it will pulsate about every 2 seconds,i can let off the pedal and go back on it and then it won't do it,might do this maybe 5-6 times a week,been doing it for the last 100,000 miles.

[markelectric]

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[MTTwister]

mark - have you checked the emergency brake light switch sender thingy? Sounds like it's shrinks back enough in the cold weather to start triggering the b-light. I would think there's an adjustment on the switch to snug it up closer to the e-brak pedal...

NOticed this on my mom's 86 Buick - brake light on - finally / accidently tapped the e-brake back up ( just a smidge) < that's a technical term > and light went out. Hopefully it's something that simple.