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Discussion Starter #1
As the title said, my issue is my cruise control sometimes doesn't turn off when the brakes are applied. There have been a couple times when you could feel the brakes being applied, yet the cruise still wouldn't disengage. My thought is it could be the switch not being activated properly. I haven't tested it yet to see if there are ever times it doesn't turn the brake lights on when only pushed a little bit. If this doesn't turn out to be the case though, what else could it be? Never ran into this before.
 

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"resident smarty pants"
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Sounds like the switch to me.
 

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Discussion Starter #3
Been a bit, but figured I would update for anyone who may stumble upon this thread.

After a bit of research I found out there are actually two different switches which disable the cruise control. There is the standard brake switch on the pedal, and another one out on the master cylinder. The one on the master cylinder is a pressure sensor and serves as a backup in case the one on the pedal fails. You will know it is being engaged if you have to actually apply the brakes to stop the cruise control, rather than just tapping the pedal. Also, the standard switch underneath the dash, attached to the brake pedal, is a multi-function switch...a DPST for those who know what that is. One of the switches in there is solely to turn the brake lights on. The other tells the PCM to disengage the cruise and tells the TCM to disengage the TC lock. I'm not exactly sure how this switch works or what wires go where, but I can tell you that one switch is NC and opens when the brake is applied. That same contact then closes a NO contact. When I opened up the old one (really easy) you could see the carbon buildup from arcing on the contacts. I put the meter on the connector side and sure enough, connection was weak at best and occasionally intermittent. I took a little fine grit sandpaper to the contacts and checked the meter. Now I had nice strong connections and no intermittent. So, I'm keeping the old one as a spare just in case I'm ever on a trip and have an issue.
 

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i ran into the same problem on an older mack truck. if you tapped the brake pedal the cruise would stay on. you had to actually apply the brakes to turn it off.
turns out the switch was bad and not turning the brake lights on when tapped or gently stepped on.
 

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"resident smarty pants"
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Thanks for the information Weatherlite!!
 
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