Driving me "Nuts" !

Discussion in 'General Chevy & GM Tech Questions' started by TestDriver, Dec 9, 2009.

  1. TestDriver

    TestDriver New Member

    I just found this site by surfing...Sounds like you folks might be able to help me out. I have a 2005 GMC Sierra long bed standard cab. 4.8 engine.auto trans ,two wheel drive. Now and then the "Service Brake System" will pop up on the cluster along with the ABS and Brake light symbols. The transmission then defaults to second gear and only responds to applied throttle but offers no engine braking (Freewheels). The first time it happened was during a snow storm in Ohio. I got the vehicle home and parked it in the garage. In the morning I took it to the local GM dealer. They scanned all the systems and found nothing..no stored codes..."Nada".
    Everything was ok for weeks after that..then the whole senerio happened again. I am a retired Test Driver/Tech. from the Arizona Daimler/Chrysler Proving Grounds, so I understand diagnosics etc. I personally think there is some sort of soft code being set by some electrical glitch somewhere. After so many engine restarts the problem goes away.
    As I said before,it happens randomly and maybe will be ok for weeks. When it happens now....I disconnect the battery and reconnect after a few seconds...that usually fixes the problem. The truck is an Arizona truck and has only been driven in the snow two or three times. It is a real anoyance when this happens as you can't always pull to the side of the road and reboot the electronics. I have searched the TSBs for that vehicle..possibly I missed something.. Any help you could offer would greatly appreciated.....Thanks y'all
  2. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    Welcome to the club!

    Hopefully some one can offer some insight into this matter for you.
  3. TestDriver

    TestDriver New Member

    Problem Solved

    OK...for anybody who gives a crap....Thru the use of a good scan tool..with a buddy..I found that I had multiple problems. Erratic gauge readings from the cluster were caused by some failed drivers in the cluster. Had the driver board rebuilt.The intermittant temp gauge from reading normal to reading "Zero" was caused by a break in the yellow ETC temp. wire inside the harness. (that was fun to find). Repaired wire..problem solved.
    The intermittant speedo reading was caused by one of the wires to the speed control. Being that I purchased the truck with only 7k miles on it from UHAUL,some unethical renter at some time had decided to cut a speed sensor wire as not to show the correct mileage at turn-in. Just before they returned the truck,they twisted the wires back together. The wire where it was twisted together was exposed to the elements causing it to be blue and corroded and all nasty looking. Properly repaired the wire connection...problem solved. By the way...any issues with the speed sensor or it's wiring can cause a host of issues that will drive you nuts trying to figure out. That faulty connection at the speed sensor is what set the ABS and brake light on the IP as well as the "SERVICE BRAKE SYSTEM" warning. It has been about ten days now and the truck seems to be functioning as designed...Hopefully this nightmare is over...
    Last edited: Dec 26, 2009

    DAREDEVIL Rockstar 4 Years 1000 Posts

    Wow. cool.:great:

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