ABS system

[medicinewolf]

I've got a 99 hoe and the ABS light has been on since I bought it. The problem is that as long as the light is on the brakes work fine, but when the ABS light goes out then I get noise from the under hood unit and the brakes feel like they are gone. Before getting the hoe I had a 99 Blazer and it acted completely opposite when the light was on or off. I've used an OBDII code reader that can pull ABS codes and did not get any codes. So any suggestion with this problem would be greatly appreciated.

 

[bowtiefreak]

My guess is a bad ABS sensor on one of the front wheels. The noise is most likely the ABS pump cycling.

What happens is that the brakes fail safe is non ABS operation. Meaning when a component fails, the ABS system turns off giving you brakes again. Our trucks have crappy brakes as it is and even without working ABS most times the tires will not lock up. So when the light is on, brakes are in "back up mode". Light is off ABS mode is technically working. I've owned my tahoe for close to 15 years and a suburban for a couple now. both 97s. I've had this issue...a few times

Temporary thing you can try is open the fuse box under the hood and find the ABS fuse, it is a large fuse like 60 amp I think. Pull it out and do a test drive somewhere safe to ensure yourself everything is cool. (I've done this many times, but again test it yourself).

Back to the sensor, a good reader can tell you where the issue is coming from but my money is on a front speed sensor. They go bad and the trucks brakes go nuts, more so at low speed.

 

[laredo1307]

I agree with Bowtie. I have one of my sensors (called a wheel speed sensor) out as well. I've already ordered 2 new ones and I'm going to change them out when I rebuild my front-end. Most likely there is just some dirt or grime build-up between the sensor head and the axle shaft so it's no getting a good reading. That's probably why sometimes it works. My light has only turned off once since it came on but it too made a noise when it did. I figure if I'm going to get in there and remove them then I might as well replace them. Rock auto and amazon have the cheapest ones I've seen.

Tip:

The repair manual is going to tell you that you have to remove the wheel hub to get to the sensor. The problem is that there is a dust shield right behind the wheel hub and you can't get a tool in there to unscrew the sensor. Trick is to take a hammer and beat the dust shield back just enough so you can unscrew it. Then beat it back into place. This will save a lot of work.

 

[medicinewolf]

thanks for the reply's i just ordered two and when I redo the brakes i'll change them out

 

[SunlitComet]

Hold the phone!!! Disconnect the 10 way connector on the abs does the light come on and stay on when key is turned on again? Unless scanner maker can certify that it can communicate with a kelsey-hayes ebc-310 control module you can't actually see codes or not. The system does not run on obd2 protocols that an obd2 scanner with abs functions can read. More details on this noise please but it sounds like the pressure is being dumped for a yet unknown reason. You really need a scanner with the right hardware and software communication to speak to an obs abs controller. To make it real easy see a dealer. They have the scanner to see what is going on. before you just tart throwing parts at it.

 

[Jerky Arm Ape]

Did you find a permanent fix for the problem?
My 97 did this ocassionaly and my 98 that I have now did it a lot so I have unplugged the connectors off of the abs system temporarily...

 

[medicinewolf]

I haven't been able to get under the truck due to the weather. on my days off it just seems to rain every time. and i don't have a garage to work in.