Sorry, it's not a Buick question... but at least it's GM :gt: This is in our "new to us" Yukon. (1999) Every once in a while, the anti-loc brakes "work" when I know I'm not on anytyhing slippery. (By "work", I mean I can feel the "vibration" or "chatter" through the brake pedal like the anti-loc valving is being activated) If you've ever slammed on the brakes in an anti-loc vehicle on ice before, you'll know the sound (and feeling in the brake pedal) I'm trying to describe. I hate to take it to a mechanic ($$) if it might be something "simple" that I could fix myself. But I don't know anything about anti-loc brakes. I assume maybe there's some type of sensor thats watching the wheel speeds and comparing them to the other wheels? Maybe there's just a sensor going bad or something? Anyone have any suggestions? Thanks! :beer
I haven't drove it much yet (just finally got the tags for it yesterday), but it doesn't seem to be very consistent. I haven't done any bumpy roads yet. o No: If I had to try to say when it happens most... I'd say it's when I first jump in it to go somewhere, it's most likely to do it the first time I hit the brake pedal. But sometimes it'll just do it out of the blue when I've been driving it for awhile.
99 yukon rick, chasing down an anti-lock brake problem can be very tricky and costly if not diagnosed correctly. your yukon being a 1999 model you have OBD-11 capability. you need to have your computer scanned for any abs trouble codes. once you access the code or codes you can narrow down to what you have to check. it could be a wheel sensor, faulty wiring, bad abs pump etc. if you have no experience with abs i would take it to a pro. good luck.
Hey Rick, ours has done the same thing since day one. We have a 92 1500 Blazer we've had since 97 and when we get in and take off the ABS box seems to pre-load itself. It was scary the first few times it happened we freaked but after talking to a mechanic friend he assured us that was the case. But we havent had it checked out and they seem fine and perform as advertised in slick conditions. Dana
Thanks for the comments guys. I'll at least have someone plug their computer into it to look for any trouble codes. That can't cost that much. Matter of fact, I have a friend that runs the local Monroe here. I wonder if he has anything for checking computers in cars. :Brow: But I feel better for now after hearing about your Blazer Dana. :TU: :beer
make sure all of your tire pressures are correct. when you apply brakes weight shifts towards the front of the truck and a front tire with marginal pressure might squat enough to make it look like the other tires are skiddin (not turnin as fast) .... its an extreme longshot, but is possible under the right conditions.
Rick, If you can give me the VIN, I can check it in our GM database to see what has been done to it in the past (under warranty). Also, if the tires on it now are a different size than what it came from the factory with (check the placard on the driver door) there is a possibility that the tire size was not programmed into the ABS module with a scan tool. If there is a mismatch, you could get an "early" or "late" ABS activation. There are probably many other things that could cause what you are referring to. But if there is a fault, there may be a code stored that would help determine cause. On a Tech 2 scan tool, you will find the ABS codes in the "chassis" selection. Other scan tools should have this also. If you know the code, I could look it up to see possible causes. I can't find out anything until Monday at work on the VIN.
You'll definately save yourself some time and money by letting someone look at it with a scan tool. If the ABS feels like it is activating when your are slowing down and nearly stopped, I have seen wheel speed sensors that are faulty and drop the actual wheel speed reading to something erroneous (usually 0). This fools the computer and activates the ABS. Also, salt water from the road tends to intrude into wire/connections and causes corrosion/headaches.
Thanks for the other suggestion guys! I'll look at the tires sizes, and pressures, and see if I can find someone with a scan tool. Don, I sent you a PM. :beer :TU:
I think what you have here is just the box setting itself up, every GM I have owned does a self test every time you start up. Its normal. If you start the vehicle with your foot on the brakes, as soon as you release the brake it will do its test. That is different than what the yukon is doing, random applications or self diagnosing..... As mentioned already, get it scanned and go from there. later Tim
Hi Tim I'll be trying to get it scanned, maybe right after the holiday madness is over. Incedently, I put over 600 miles on it this weekend ( 2 long road trips ), and I think it only did it once or twice the entire time. Then my wife and I drive to the outskirts of town (5 miles?) a few minutes ago, and it did it 3 times during that short trip. ou: It's always when I'm going less than about 1 or 2 MPH, and barely touching the brakes. I'll get it scanned pretty soon and see what they can tell me. Thanks for the input guys. :beer
This is not directly related to your problem but... here is a headsup. The ABS motor pump controller is very prone to go beserk on the 99(new style) Chevy/Gmc trucks. The one on my 99 silverado went out at 46k miles. A friend had his go out at 44k miles on his GMC. The switch will go bad and the ABS motor will continue to run (even with the key off) until the battery goes dead, or the battery is disconnected(or fuse pulled). This is a $800part/$100labor repair!!! I'm sure there is a GM tech or 2 on this board that can confirm this. So anybody with these new style trucks (I dont know if they fixed this problem for the 2000-2003 models or not) beware of this problem. However there is a company that repairs these modules (although I haven't personally used them-yet). I just thought somebody will need to know this! Circuit Solutions
Rick, I have the information regarding your Yukon ABS system. There is also a bulletin on early activation of ABS. Don't know if it will help, but if you e-mail me or provide your e-mail in a PM, I will forward the information to you.
