OK I know this topic has been discussed but I still need a little direction. 1999 Silverado, 4wd, auto. ABS/Brake intermittently comes on (but never does in a MN winter) I get code CO265- EBCM relay circuit and Stop Light Circuit. My mechanic reseached the code and told me to change stop light switch (which I did but still lights still come on) and to check "purple wire from stop light switch" I see the purple wire going from the stop light switch but do not know where it leads to to check for power. I know it all leads to the EBCM but I feel it's a short somewhere as it only comes on when the weather is warmer (May- Oct) and also when I drive on bumpy roads. I have checked and cleaned all grounds to chassis etc and battery. Thanks for any help in advance!

 

this is going way back to old school but......did you check and clean the grounds at the tail lights? also if you have trailer wiring check all of it too. how about excessive wear at the site of the brake light switch? a bad bulb socket will do this too. just some ideas to look into........dont let the skeeters get ya......lol

 

I did not check the ground at the tail lights. Where can I find the grounds? I'll check the bulbs too. And now that you mention it, I did not have this problem until I added the plug in electric brake controller into my truck down buy my left foot module. But the weather was getting warm then too so I banked on that as that's the most consistent trigger I see at this point. I drove it last night in a cool rain for 45 miles and it never tripped the dash ABS lights on. I'm guessing it's a short somewhere that stays connected when cooler?????

 

The black wire in the harness is the ground check it with a DVOM and hand check it, also Im not sure where but find where the grounds meet the body or frame and clean them also.

 

thanks! What should the readings be for Ohms or volts on this ground?

 

no Ohms it should "tone out" or show 0 if it is a good ground in relation to another ground or body panel