I've been using 'CRC QD Electronics Cleaner'. I'll do it for a while more and try WD40 as well. I'd love for this to work.I have had luck using wd-40 to clean contracts in switches. The thing is sometimes it's hard to get the oil/cleaner into the switch. Soak it good and work the crap out of it.
As for the trailer if all the brake lights work then that's not it.
It very well could be the switch.
Did you double check that other switch under the dash on the brake pedal??
If so sounds like it could be the set switch, the right way to do this is the test procedure, it's posted in this thread I believe.
If you are feeling lucky you could just go for it and get the switch. about $120 shipped. Looks like you'll need a steering wheel puller and some regular tools is all.
It is an automatic trans right? If not there is a clutch switch too.
Also, fuse 10 under the hood. Need power there.
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I pulled the second switch (on the left) from the brake pedal. It was operating and I tested it for continuity when open and it had continuity.
I'll be honest, I looked at the test procedures and don't know enough to do some of those steps. Thank you for the reminder - if further cleaning of the switch doesn't work, it's probably time for me to learn more about all of that.
I may end up trying to get a whole new lever.
It is an automatic.
I checked the CC fuse along with the STOP fuse for continuity early on in the process. I'll probably go back and check the CC fuse again just to be sure.
Thanks for your thorough response!