Vehicle 1996 Chevy Blazer 4door 4x4 4.3.

I recently replaced the Hub assembly,rotors,ball joints,ABS sensor on the front of my blazer. The hub assembly was not the kind with the ABS attached. So I got the ones that had the dust shield attached.

I did these repairs because the bearings were going out and the ball joints were long over due and the left front ABS senor harness was broken in half causing the light on the dash to come on.

So I installed all the parts and everything works fine. All lights went off. I went on a longer test run today to help the computer relearn itself since it was unplugged for about a week. When I was driving at 35mph I started pressing on the brakes to make a turn and the abs went off in the pedal..No light come on. After I cleaned my shorts I turned around and head home. I tries several more times and it happened. When I was slowing down from 15mph to turn into my driveway it did not happen and it didn't go off when i came to a complete stop. My neighbor is a mechanic for a Ford dealer and said sometimes you have to adjust the air gap on the new sensors. He also mentioned some guys can use a paper clip to measure the old sensor position then bend the new one to match it and this will sometimes work.

What do you all think? Does it sound like an air gap issue? Is there a way to check it and fix it?

 

You can set the airgap with a multimeter and some time. You want the sensor output to be >250mV-AC when you spin the hub.

Also, take a look at the reluctor ring (the square toothed ring on the CV shaft) and make sure that the grooves are clean. Brake dust likes to accumulate in these grooves which tends to alter the standard square wave output that the ABS control module is looking for and can cause the symptoms you are experiencing.

 

Swartlkk

I am borrowing a friends multimeter. It's a craftsman 82345. Not sure if it is the one for the job. I have never used one. It says it's a 200mA max. I don't see anything that shows AC on it either. I have it hooked to the sensor and spun the wheel with it on the 200mA but nothing showed when I spun it. Any suggestions? Also my new hubs have more of a rounded tooth on them for the sensor to read. Not like the old that has the more squared tooth. I dont think it will matter since it's a new sensor but thought maybe it was worth mentioning.

Also. Where is the ABS fuse? I figured I'd just rule that out. I didn't see anything under the hood and nothing in the fuse box on driver side labeled abs

 

Sorry, that was supposed to be mV-AC, not mA-AC. I fixed it above. Put that multimeter in the 200V range with the squiggly line above the 200V. Hopefully it will show you at least down to the hundredths of a volt (1V = 1000mV).

The ABS fuse... It appears that the BPMV (brake pressure modulation valve) is powered through a fusible link. It does get an ignition feed through the BRAKE fuse (#12 in the fuse box off the end of the dash), but I couldn't tell what else that powered. It does go through the brake light switch though. You could try disconnecting it and seeing if the brake lights still work.

 

OKay. tha makes more since now looking at this meter. I got a reading of

01.7-00.3 not sure what that translates to. I pulled the brake fuse and still have lights. I put it in until I try fixing this abs issue. If I cant get it solved ill just pull it until I figure something out or just unplug the sensors.

I read the info you have listed on cleaning and checking the air gap but I do not see how I will be able to bed this bracket. It is very thick.

 

So I slept on it and was thinking that maybe just simply bleeding the brakes would fix it. I figured since I had to compress the piston to fit the new rotors on that maybe some how air or debris got pushed back into the system and the abs is being sensitive towards it.

Would this make sense? Is there a certain way to bleed the brakes?

 

I hate to bump an older post, but I'm having the same problem on my 96... Did you ever fix your brakes? I replaced a bad sensor (broken wire) and now the ABS light is off but ABS comes on nearly every time I hit the brakes. I took it to the shop and hooked it up to the scanner and the wheel speed was lower than the other two sensors... I'm thinking it may be the air gap. I have unplugged the sensor in the mean time.

I checked the resistance of my offending sensor- 1960 ohms. I read somewhere that the resistance should be between 950 and 1200 ohms. Does this sound right?

 

As suggested, test the mV-AC output while spinning the wheel. Result should be >250mV-AC. Anything lower and the sensor will not properly feed information to the EBCM.

 

Do I have to jack up both front wheels to spin them? I put the truck in neutral and tried to spin the front wheel with the other one on the ground and they are locked together. I have a 1996 4x4.

 

You should be able to spin one wheel with that wheel in the air and the other 3 on the ground with the transfer case in 2HI. You will not be able to spin the wheel if you have 4HI or 4LO engaged.

With all 4 wheels on the ground and the transmission in 2HI, can you manually spin the front axle?

We're kind of straying from the topic here though...