SOLVED Low speed ABS activation Chevy Trucks
Created on: 2018-06-22
If the ABS pump engages and the brake pedal presses further than usual and pumps soft and hard, engaging the antilock brakes, this video has a solution
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step 1 :Removing the Wheel
- Loosen the lug nut covers with a 12mm socket
- Pull the center cap off the wheel
- Loosen the lug nuts with the wheel on the ground
- Raise and support the vehicle
- Remove the lug nuts
- Pull the wheel off the hub
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step 2 :Removing the Brake Rotor
- Remove the two 18mm bolts from the caliper bracket
- Thread on one lug nut to hold the rotor in place
- Pull the caliper off the rotor
- Hang the caliper aside with a bungee cord
- Remove the placeholder lug nut
- Pull the rotor off the hub
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step 3 :Removing the ABS Sensor
- Apply rust penetrant to the ABS sensor Allen bolt
- Remove the 6mm Allen bolt from the ABS sensor
- Remove the sensor from the wheel knuckle
- Unclip the sensor wire from the steering knuckle with needle nose pliers
- Put the sensor gasket aside
- Pull the sensor and wire away from the knuckle
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step 4 :Cleaning the ABS Sensor and Wheel Knuckle
- Spray brake parts cleaner on the sensor mounting area
- Clean off any grease or debris with paper towels
- Clean the sensor mounting area with an emery cloth
- Remove rust from the sensor mounting area with a file
- Spray brake parts cleaner on the sensor mounting area
- Allow the brake parts cleaner to dry
- Apply a thin coat of spray paint to the area
- Clean both sides of the sensor gasket with an emery cloth
- Clean the sensor with paper towels
- Check that the sensor is flat
- Clean the sensor with brake parts cleaner
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step 5 :Installing the ABS Sensor
- Place the gasket on the ABS sensor
- Press the sensor into the wheel knuckle
- Fasten the Allen bolt into the sensor
- Clip the sensor wire to the wheel knuckle
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step 6 :Installing the Brake Rotor
- Slide the rotor onto the hub
- Thread on one lug nut to hold the rotor in place
- Clean the rotor with brake parts cleaner
- Remove the bungee cord from the caliper
- Place the caliper on the rotor
- Fasten the two 18mm bolts into the caliper
- Torque the two 18mm bolts to 133 foot-pounds
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step 7 :Installing the Wheel
- Remove the placeholder lug nut
- Lift the wheel onto the studs
- Start the lug nuts by hand
- Lower the vehicle to the ground
- Torque the lug nuts to 100 foot-pounds in a crossing pattern
- Press the center cap onto the wheel
- Tighten the lug nut covers with a 21mm socket
- Repeat this procedure on the opposite side
Tools needed
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Socket Extensions
Torque Wrench
Jack Stands
18mm Socket
Brake Parts Cleaner
Pick
21mm Socket
File
6mm Allen Wrench
Paper Towels
Bungee Cord
Ratchet
Floor Jack
Needle nose pliers
1/2 Inch Breaker Bar
22mm Socket
Hi. I'm Mike from 1AAuto. We've been selling auto parts for over 30 years!
Maybe you've felt this at low speeds every now and then, sometimes in a parking lot or coming to a stop sign. The antilock brakes will engage when the brake pedal's pushed. You might hear the ABS pump groan from under the truck, just below the driver seat. When the ABS pump is pumping, brake pedal feel becomes soft, it goes down lower than usual. The brake pedal is about three quarters of the way to the floor, begins to pump itself back up. The pedal pressure pushes against your foot pressure. Brake pedal goes from normal to soft to rock solid within about two to three seconds. The problem comes from rust buildup on the front knuckles, which pushes the ABS wheel speed sensor away from the tone ring on the axle, giving a false signal to engage ABS.
We need to remove the center cap to the wheel, so we can loosen the lug nuts to the vehicle on the ground. I'm going to use this 21 millimeter socket. These shouldn't be on here too tight; these are just plastic caps that thread onto the actual lug nuts. You should be able to break these free by hand. If not, you might have to put a small wrench on here. But these come off pretty easily. They won't screw all the way off. You just loosen them up. They stay captured in the cap. Go around the edge and grab them all and the cap will come right off.
The lug nuts are a 22 millimeter socket. I'm going to use that at the end of a breaker bar. We'll loosen these up while the vehicle's on the ground. This way the wheel doesn't turn on me. Then I can raise and support it, and take the wheel off. Give it a couple turns to loosen them up. Now I'll raise and support the vehicle. We're going to take the lug nuts off and remove the wheel and tire. Take the wheel off. Put it aside.
The ABS is being triggered because of a rust buildup where the sensor mounts inside of the steering knuckle. Unfortunately, the way this is set up, the ABS wheel speed sensor is inside of this dust shield and on the inside of the rotor. So we're going to have to remove the caliper and the rotor to get to it. We'll clean it up and reinstall it. You should do this for both sides, because you really won't know which side is causing the problem, and the procedure will be the same for both, but that should fix that weird ABS engagement at low speed for you.
I'm going to use an 18 millimeter socket and a breaker bar. I'll loosen the bottom caliper mounting bolt, and then I'll loosen the top one. I'm not going to loosen the slide pins, I'm going to remove the whole caliper as one piece and hang it. Turn this a little bit. Give myself some more clearance. There we go. Once they're broken free, switch to a ratchet. I’m just going to hold on to the caliper so it doesn't drop. This rotor is pretty loose. We don't want it to fall. So I'm going to take a lug nut and just thread it on there lightly. It'll keep the rotor from falling off, until I'm ready to remove it.
Slide the caliper off the rotor. I'll put it on top here. Take a bungee cord, just wrap around it. Just so it doesn't fall off. Take this lug nut off.
We'll pull the rotor off; we're lucky this hub has been replaced, so it comes off pretty easily. If not, you may need to spray some rust penetrant in here and hit this rotor off. We got lucky; this one came off.
I'm going to spray some rust penetrant in here. There's an Allen bolt, six millimeter, and a lot of dirt buildup in here, but what's happening is the surface that this ABS sensor sits on right here in this plane gets rusty, and it pushes it away from the tone ring inside, and gives that weird ABS false signal at low speed. So we're going to carefully remove it, so I'm using a six millimeter Allen socket on my ratchet. I broke it free. We'll put the bolt aside, so we can reuse it.
Then I'm going to try to wiggle this out with my fingers. So that actually came out nice and easy. I'm going to take some needle nose pliers and squeeze this clip in, because I want to give myself a little more wire to play with. So we'll just push this out. Now I've got some more wire to work with. We'll feed this out of here, so I can lift it up and out. There's a little gasket here. Of course, this is magnetic; that's how it works. I'm going to clean all that up afterwards. Let me just slide it out of the way here. Now I'll put this gasket aside, so I don't lose it.
I'm going to spray some brake parts cleaner in here, and clean it up. I'll wipe away any dirt and grease. We're going to use some emery cloth. We'll clean up the top. This one's not in too bad a shape, because I think this hub is fairly new. You may need to use a file. If you use a file, you want to make sure it stays nice and flat. You don't want to put a gouge in this, or make it crooked or curved. As long as it's sitting nice and flat, the ABS wheel speed sensor should work correctly. So I'm going to use a file and keep it nice and flat. Clean the rust off. Spray some more brake parts cleaner in there.
You can use rusty metal primer or any type of spray paint, really. We just happen to have some red spray paint. We're going to use that. Just put a thin coat over this, it helps preventing from flash rusting again. That's it.
I’m going to clean this plate that came with the sensor with some Emery cloth. Just make sure it's nice and clean and doesn't have any rust on it. We're doing it on a flat surface. I want to keep it nice and flat. Do both sides.
Now wipe all the grease off of the sensor. Make sure it's nice and clean, because even a little bit of grease can hold it up. And wipe off any metal that's stuck to the magnet. There’s a bit of silicone sealer on here; I want to peel that off. I'll just use a pick to get that off. One thing to look for, is you want to make sure that this sensor is nice and flat, like that one is. If it's got any little bit of a curve to it, if this hub had been more rusty, it would've pushed the plastic and bent it up, and it's not making good contact towards the reluctor wheel. So in that case, you need to replace the sensor. This one looks like it's in good shape, it's nice and flat. I'll just check the other side. Yup, it looks pretty good. There's some stuff stuck on there, and I've cleaned that off. Clean it off with brake parts cleaner.
Reinstall the little metal washer. Don't forget, it's going to go through the opening. Put it down into place. You might have to turn it a little bit. Push it down in. Make sure it's nice and flat. Reinstall the little Allen bolt. I'll tighten it back up. You don't have to go super tight, you don't want to kill it. Feel it get tight, and just stop. Looks good. Push this clip back in.
Reinstall the rotor. Want to put a lug nut on here, so it won't fall off on me. Take some brake parts cleaner, and any greasy hand prints I got on here, just clean them off.
Undo the bungee cord. Make sure I take it out of here. Reinstall the caliper. I'll turn it out, so I can get to it. Slide it up into place. Get the bottom one caught. Whoops. You might have to wiggle it around a little bit. We'll run these down. We're going to torque these caliper mounting bolts to 133 foot-pounds. Once it clicks, you're all set. This side's complete. We're going to do the other side. It's the same exact procedure. We'll clean that up too.
I removed the lug nut I used to hold the rotor in place. Don't forget to do that, you'll have a heck of a time trying to put the wheel on if you got a lug nut already on there. There are lug nuts all started by hand. Use the ratchet to snug these up. We're not going to fully tighten them, because I will torque it with the vehicle on the ground. We're going to torque the lug nuts to 100 foot-pounds in a cross pattern.
Reinstall the wheel cover. Line it up to the lugs, and take that socket and just thread them on by hand. They'll thread down and lock in place. This side is complete.
Thanks for watching. Visit us at 1AAuto.com for quality auto parts, fast and free shipping, and the best customer service in the industry.
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