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93' GMC Yukon Brake Problems


Tim Ferris's Avatar
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03-09-05, 07:21 PM   #1  
Tim Ferris
93' GMC Yukon Brake Problems

I have a 93' GMC Yukon with an automatic transmission and 160K miles that I bought from a state auction, previously used by the TDOT (Tennessee Dept of Transportation). It has been a great vehicle but recently I have been having some problems with the ABS. I typically only drive it to and from work, about 20 minutes of mostly highway mileage. The brakes work fine for the first few minutes but then they make this horible sound when pressed and I feel resistance on the brake pedal. The sound only lasts for a few seconds and then the ABS light comes on. After that the brakes work fine again but the transmission seems to slip when going into 2nd gear. I have been told that it could be a sensor in the ABS system that could be causing the problems. Is it possible for the sensor to affect the transmision? Any advice would be greatly appreciated.

Thanks,
Tim

 
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Mr. Dummas's Avatar
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03-10-05, 06:50 PM   #2  
When you use the brakes and feel this resistance, is it when the vehicle is just about stopped? And this noise you hear, does it corrospond with this resistance feeling? If so, you probably have a wheel speed sensor dropping out. You are braking to a stop and all 3 sensors are puting out the same speed. When one of these sensors drop out, it no longer puts out a wheel speed signal and your ABS is activated briefly due to the wheel speed variance. In this situation, you will need to have your truck driven by a technician with a scan tool connected so he can monitor the wheel speed data to determine which sensor it is that may happen to be dropping out. There are 3 sensors total, left front, right front and rear. Seldomly ever do I see the rear go bad, so it is more than likely on of the fronts.

Your transmission problem has nothing to do with the ABS system. I would say its time to have your transmission overhauled.

 
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03-10-05, 07:22 PM   #3  
Tim Ferris
That is correct, the noise and resistance on the brake pedal do happen at the same time and it is right before I come to a stop.

Thanks for the information. Once I find out which sensor is dropping off, is this something that I can replace myself?

 
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03-11-05, 05:19 PM   #4  
Yes, it is very simple. You will need an allen socket to remove the bolt that holds the sensor to the wheel bearing. From there, just follow the harness up to the top of the truck's frame and there will be the connector. Its a pretty straight forward repair. If by chance your ABS light is on after the repair, have a tech pull up the DTC on his scan tool. There have been many cases where an after market sensor has been no good. Let us know how it turns out for you.

 
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