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dashboard warning lights

Discussion in 'Chevy Trucks' started by blublzr, Oct 16, 2012.

  1. blublzr

    blublzr Member
    Messages: 35

    i have a 1999 silverado 1500 , and recently the following dashboard warning lights have been coming on . they are the ABS & BRAKE LIGHTS. any ideas?

    thanks, wil
  2. Banksy

    Banksy PlowSite Veteran
    Messages: 3,113

    Wheel speed sensor, but you'll need an ABS scanner to pin point it.
  3. Plowtoy

    Plowtoy Senior Member
    Messages: 929

    If the sensor isn't working at all, he could measure for AC voltage at the sensor to figure out what one isn't working. Just need a DVM and a floor jack
  4. theholycow

    theholycow PlowSite.com Addict
    Messages: 1,180

    ^What he said.

    There is a TSB explaining it in detail but it's really easy. All you'll need is a jack and a multimeter that can measure AC millivolts.

    Jack truck. Disconnect ABS plug (follow wire up until you find the connector behind the UCA/shock mount). Insert multimeter probes into connector; standard cheap probes fit nicely if you go straight in past the pin. Set meter to display AC millivolts. Spin the wheel by hand as fast as you can. If it reads less than 350mv then that's the side with the problem.

    Once you've identified the problem:
    1. Remove wheel, brake caliper assembly (no need to remove caliper from bracket, just remove bracket from truck), brake rotor.
    2. Carefully and thoroughly clean area around ABS sensor, then remove sensor. I needed an uncommon Torx T-35 bit, which needed to be hammered into the screw to get a good grip on it...nothing else would fit and grab.
    3. Plug the hole with something clean and tough.
    4. Thoroughly clean the mounting surface. A wire brush and brake cleaner may suffice. Sandpaper may be necessary. Don't grind it down until it's misshapen, just remove corrosion and dirt.
    5. Put it back together and test again. It may be fixed. Don't forget to clean the sensor carefully and apply good quality wheel bearing grease liberally. Also put anti-seize on the screw threads and might as well fill the torx/allen screw head with grease to help reduce future corrosion. Finally, don't forget to torque the brake caliper bracket bolts properly, after you clean them and apply red threadlocker.
    6. If it's not fixed you'll need a new sensor. I couldn't find one at parts stores but went to a self-service junkyard with my meter and pulled a couple good ones.
    7. Go for a drive. The ABS light should go out after a bit of driving. Success.

    If replacing the sensor doesn't fix it then your hub is bad. These trucks eat through the integrated unit hub/bearing pretty badly so it'd be no surprise. Might as well check for the most common symptoms before you start worrying about the ABS sensor since new hubs come with new sensors. While jacked up, spin the tire, make sure it spins smoothly and keeps spinning without much drag; if it drags or grinds then it's bad. Grab it top and bottom and try to rock it in/out; it shouldn't wiggle, if it does then it's bad. It can pass those tests and still be bad, evidenced by the ABS sensor replacement not helping or by any of a million totally different noises while driving.
  5. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,329

    I had the abs issue on my wife's 04 Yukon. With the miles it had on it at the time, it didn't seem worth it to replace just the sensors. For not much more I replaced both hubs. I just had to order one for my truck, drivers side is going on me. I found a Timken on Amazon for around $115. After paying for the next day shipping it cost me $152. I couldn't get a good one locally for under $300.