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'97 Cheyy Chyenne brake switch access for break controller?

K

klover

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Having a heck of a time trying to get the blue wire hooked up because I can't seem to
get to the cold side of the brake light switch. Does the harness to the switch unclip, or does the
entire switch need to come out? Can't even get my hands in there.
Thanks for any ideas.
 
there is a small pin on the underside of the dash. I call it the under dash electrical center. it is where your flasher relay and other electrical items are located. it will be in front of the e-brake mounted to the firewall.

on this panel there will be a empty pin towards the bottom of the panel. using a test light, touch them all, then hit the brake, and touch them all again. go woth the one that is dead when foot off, live with foot on. AFAIK, all brake controllers just use this for a signal, so even though it is a small pin, no load will be put on it, so you wont hurt a thing.

IMO this is a far better way of wiring, as you dont comprimise the harness.

good luck!
 
Probe as I might on each pin, nothing lights up with the brake applied. I am hoping to find an electrical diagram to try to figure out which wire to tap into. I just might be able to unplug the harness at the switch, but I still need to poke for the cold side wire in a very difficult spot before I can pull the end to a workable location for tapping into. I need to have hands that are half my size, and there are lots of sharp burrs to cut your hands on.
 
that is weird, got a good ground on the test light? no broken wires under the dash? I can get the exact pin if you want.
 
I get some hots while probing, so ground on the tester is good.

I have been trying to find an electrical diagram to see where I can tap the cold side wire away from the brake switch. I found for a gas '98 k2500 and see it has four wires from the brake switch (I believe mine to be the same). One is a white wire going to the cruise control module.

In another thread I read my '97 K2500 has the cruise control module as part of the PCM. My thought now is to get the pin out description of the PCM for the "brake on" pin, and tap into that wire along the harness. It might be easier to get to.

Yes, I find it very wierd that I can not find a pin at the dash solenoid board that lights when the brake goes on. Normally,
the threads show they are labled with the "NAT" molded letters. There are lots of added wires on this rig from before due to lots of radios, but I have yet to understand them all. I don't believe there was a brake controller on this rig before.
 
autozone.com has wiring diagrams online. Open an account, add your vehicle and go to 'repair manuals', chassis electrical. Not complete but it does show two circuits for the brake switch. On mine the Brown comes from the brake fuse, hot in run, normally closed to purple to ECM F5. The orange comes from the stop fuse, hot all the time, normally open to yellow to ECM A7. The brown/purple disables the TCC, the orange/yellow is the brake signal--it's the one you want. (if color codes are the same)
 
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