When does the ABS activate at low speeds?

Make and Model > Chevrolet > Astro Van > ABS Activates at low speeds… GM has issued a service bulletin #02-05-25-006B to address a condition where the ABS activates at low speeds, usually less than 5-mph) even though the vehicle is not in a skid condition. The ABS activates at low speeds bulletin applies to the following vehicles:

Why does my car have an unwanted ABS activation?

These vehicles may have a condition that permits corrosion to occur between the front hub/bearing assembly and the wheel speed sensor. If the brakes are applied while the vehicle is traveling at a speed greater than 3.7 mph but less than 10 mph, the corrosion may cause an unwanted ABS activation.

Why is my ABS sensor signal so weak?

Possible causes of a weak speed sensor signal include corrosion around the sensor or a buildup of metal particles at the sensor tip. Anything that separates the sensor from the signal generator may be enough to weaken the signal and cause an ABS activation complaint.

When to use ABS on a GMC Sierra?

ABS is a welcome safety feature when driving in inclement weather or traversing irregular road surfaces. It’s more of an annoyance if it activates when no hazards are present. I’m working on a 2001 GMC Sierra 1500 with the 5.3L engine that came in with a complaint of low-speed ABS activation. I road-tested the truck to confirm the problem.

Why do I get false ABS at low speeds?

The rust forces the sensor away from the reluctor and it cannot properly detect proper ABS braking conditions, so you get false ABS activates at low speeds. The process or rust moving the sensor is called “rust jacking,” since the force of the rust moves the sensor upwards. To test the sensor, connect a digital voltmeter to the sensor connector.

What causes a car to activate its ABS system?

This problem usually starts with the wheel speed sensors. A weak signal from a sensor is interpreted as a locked wheel, which triggers the computer to activate the ABS system and release brake pressure in an attempt to unlock the wheel. The driver might experience a longer than normal stop.

Why is my abs on at 15 mph?

The most common complaint on older vehicles is ABS activation at speeds between 3-15 mph. This problem usually starts with the wheel speed sensors. A weak signal from a sensor is interpreted as a locked wheel, which triggers the computer to activate the ABS system and release brake pressure in an attempt to unlock the wheel.

Are there any GMC trucks with unwanted ABS activation?

This kind of unwanted ABS activation has apparently been occurring on a regular basis on 1999-2002 GMC and Chevy trucks, as GM has issued a product safety bulletin (No. 05068C) that addresses these symptoms. I’ll summarize its contents here.

What to do if your ABS sensor is distorted?

Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor. Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats.

What does rust do to an ABS sensor?

The process or rust moving the sensor is called “rust jacking,” since the force of the rust moves the sensor upwards. To test the sensor, connect a digital voltmeter to the sensor connector.

Is there a problem with my Silverado ABS?

Sorry…

Why is my abs light on but no code?

The wheel sensors are where I would look next. If the wires are broken, shorted, etc. then the ABS won’t function correctly. BTW, the pulsing is the ABS unit kicking in to prevent brake lock-up probably because it senses a locked wheel (hence the wheel sensor) incorrectly.

Why are my abs cutting in at low speed?

According to the capture, our problem is only in one area of the rotor, and these shiny spots correlated well with the recorded capture, but a distance problem between sensor and tooth isn’t the problem here. The shape of the teeth has already been covered and eliminated; it was the make-up of the shiny spots that was now in question.

What kind of sensor is used for ABS?

The system uses four variable-reluctance sensors, one attached to each corner hub. Touching very briefly on sensor theory; the output of this sensor is alternating current which is generated as a moving reluctor (a metal object, in this case our wheel rotor) passes into, through, and out of the sensor’s magnetic field.

When does the Abs go on in a car?

It’s normal for the strength (amplitude) of the signal generated by an ABS sensor to gradually diminish as wheel speed decreases. But if the signal drops below a certain threshold, the ABS controller interprets this as abnormal deceleration and the ABS kicks in. This typically occurs just before the vehicle comes to a stop, at speeds around 5 mph.

Where can I get an OBD code for my abs?

It’ll tell you which sensor is throwing the trouble code. The wheel speed sensors won’t throw an OBD code, so it won’t show up on a standard code reader. Go to AutoZone and ask for their loaner program code reader (NOT THE STORE READER). The loaner does ABS codes.

What kind of lubricant to use for ABS?

Use ONLY Rust Penetrating Lubricant, P/N 89022217 (Canadian P/N 89022218). Install either the original sensor or a new one in the hub and secure the sensor.

When does ABS kick in in Chevy Silverado?

I have a 1999 Chevy Silverado 1500 Z71 and am having issues with my ABS. When coming to a stop, the ABS will kick in when under 10ish mph. I started to happen after I changed my driver front wheel bearing. It was a cheap Ebay bearing, so, now, about 3-4 months later, I bought a new wheel bearing and installed it today to see if it changed. Nope.

Why does my abs come on when I shut the truck off?

Nope. When I changed it a couple months ago, the ABS & Brake light would come on but reset when I would shut the truck off. The ABS pump is not having the typical issue where it runs non-stop, but it kicks in for no reason. Swhitney is right. The problem is called “unintended low speed ABS activation”.

How can I get ABS on my truck?

There was a recall for trucks in the “rust belt”. Undo the torx screw that holds the ABS “reader” to the hub and pull it out. Put a piece of paper towel in the hole and use some emery cloth to remove the corrosion on the mounting pad. Just a millimeter of corrosion will hold the reader far enough away from the sensor to cause low speed activation.

What causes a soft brake pedal on a Chevy?

Soft or Spongy Brake Pedal: Too much air in the system due to improper bleeding is usually the cause of this problem. However, it can also be due to fluid loss or a low fluid level. Bleed the brake lines as recommended by Chevy to fix this. You could also have a ballooning brake hose when the brakes are applied.

What causes the brake lines to bleed on a Chevy?

Bleed the brake lines as recommended by Chevy to fix this. You could also have a ballooning brake hose when the brakes are applied. Check your brake hoses for anomalies. Excessive Brake Travel: If the brake linings are worn, the drum brakes are misadjusted or the brake lines have air in them, you will have this issue.

What causes a clutch to fail under heavy load?

Each of these failure modes has different causes, and how it failed can be a big help in figuring out how to fix it. A clutch that doesn’t engage fully, or slips under heavy load, is the normal failure mode of a worn out friction disc of pressure plate that has lost its tension.

What was the problem with my 1991 Chevy 4WD?

1991 Chevy 4wd problem | The largest community for snow plowing and ice management professionals. Find discussions on weather, plowing equipment and tips for growing your business. While continiuing to go through and get all the trucks ready I discovered a problem.

When did Chevy Suburban Service traction control issue occur?

The topic originally came up in the Chevrolet Forum way back in 2011. And it appears that a lot of folks had encountered the same issue, yet a solution remained elusive. Most of the time, it happens exclusively on the 2007 model year Suburban.

Why does my abs go bad under 5 mph?

A dealer has AT LEAST a tech2 scanner which has graphing capabilities. Its easy, you graph the data of all 4 wheels (3 with a solid axle), stop the car and the wheel the loses signal is the culprit. Usually under 5 mph the bad will read 0 mph indicating a lock wheel to activate abs.

What kind of transmission did the Chevy Suburban have?

This model generation was based on the Chevrolet Advance Design series of pickups. Beginning in 1953, the Hydra-Matic 4-speed automatic transmission was available in GMC models and in the 1954 model year Chevrolet Suburbans.

When does the Chevy Suburban go out of production?

It would return as an exclusive to rental, fleet, and government services with the eleventh generation starting with the 2016 model year with a 4WD LS and LT trim option, but soft sales would result in Chevrolet discontinuing production on this feature in 2020.

How many miles does a Chevy Suburban 2500 drive?

1st owner drove an estimated 0 miles/year • 2nd owner drove an estimated 0 miles/year • 3rd owner drove an estimated 9,246 miles/year • 4th owner drove an estimated 0 miles/year • 5th owner drove an estimated 0 miles/year.

What are the symptoms of a bad ABS control module?

1. Unresponsive brake pedal. In certain cases, depending on the model of vehicle, when the ABS module fails, the brake pedal may become unresponsive. This is an obvious problem, as an unresponsive brake pedal will not stop a vehicle, or will not be able to do so in an adequately safe manner.

How does the ABS system work on a car?

The ABS system is made up of the ABS module, and ABS sensors at each wheel. The sensors detect wheel speed, and will send a message to the ABS module to rapidly pump the brakes when it is detected that the vehicle is skidding or has lost traction.

What happens when the ABS system is not working?

The sensors detect wheel speed, and will send a message to the ABS module to rapidly pump the brakes when it is detected that the vehicle is skidding or has lost traction. When the ABS system is not functioning then loss of traction, skidding, and hydroplaning are far more likely to occur under heavy braking conditions.

What should I do if my abs is not working?

4. Rotate the wheel clockwise approximately one revolution per second. The minimum reading should be at least 350 ACmV’s. If the reading is less than 350 ACmV’s, remove the wheel speed sensor. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.

Why is my abs not working at low speeds?

Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set. The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

What happens when your ABS sensor stops working?

Not only can you lose anti-lock brakes, but also other functions, such as stability control, traction control, roll stability and hill-start assist. When the sensor stops sending information, the computer shuts down these systems as well. However, you can experience problems even when the ABS light isn’t on.

What are the symptoms of a bad ABS system?

Symptoms of a Bad or Failing ABS Control Module 1 Unresponsive brake pedal. In certain cases, depending on the model of vehicle,… 2 Brake pads require more effort to push. 3 The ABS Light is on. The most common sign of an issue with the ABS system is… 4 The brakes are locking up. When it is functioning correctly the ABS system is designed…

There’s no play or harshness when spinning the hub bearing by hand and I don’t see any damage to the speed sensor. When the ABS kicks in at low speeds on dry pavement, the usual cause is a weak signal from an ABS speed sensor.

When do ABS kick in when coming to a stop?

When coming to a stop, the ABS will kick in when under 10ish mph. I started to happen after I changed my driver front wheel bearing. It was a cheap Ebay bearing, so, now, about 3-4 months later, I bought a new wheel bearing and installed it today to see if it changed. Nope.

When does a bad ABS wheel speed sensor fail?

When the ABS wheel speed sensor fails, the ABS light is probably one of the first sign your will notice of all bad ABS wheel speed sensor symptoms. At first, it might simply cause the ABS warning light to come on. However, when the other systems stop functioning properly, you might also see the traction and stability control warning lights too.

What happens when you have a false ABS activation?

False activation incidents involve the ABS modulator taking over braking or intervening to restore vehicle stability. The customer may feel feedback in the brake pedal like a pulsation or sudden drop. Some may also experience a drop in power or the vehicle may suddenly pull in one direction.

Which is more advanced stability control or ABS?

The modern equivalent is now called Stability Control and is far more advanced than just ABS.

Why does my ABS pump run non stop?

The ABS pump is not having the typical issue where it runs non-stop, but it kicks in for no reason. Swhitney is right. The problem is called “unintended low speed ABS activation”. There was a recall for trucks in the “rust belt”.

What to do when ABS kicks in when almost at complete stop?

Put a piece of paper towel in the hole and use some emery cloth to remove the corrosion on the mounting pad. Just a millimeter of corrosion will hold the reader far enough away from the sensor to cause low speed activation. Put some grease on the mounting pad and tighten the reader back to the hub. Problem solved.

Is the pulsing brake pedal necessarily an ABS issue?

Then the ABS light turns on and brakes work normally for the rest of the time. It is not easy to reproduce this issue. On average it happens once every two days. Is the pulsing brake pedal necessarily an ABS issue?

Is there a problem with my ABS system?

The pedal pulsates or “ratchets”, there is a groaning sound, and the truck stops decelerating as well. The service department has told me they have used all diagnostic tools available and an inspection of the brake system yields no clues. It feels as if the ABS system is sensing a need to come on when there is no need. But hey, I’m just a pilot.

What should my abs speed sensor reading be?

Rotate the wheel clockwise approximately one revolution per second. The minimum reading should be at least 350 ACmV’s. If the reading is less than 350 ACmV’s, remove the wheel speed sensor. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.

What causes ABS to kick in when almost at complete stop?

Theres a TSB out there 03-05-25-007d that says its caused by an increased air gap between the wheel speed sensor and hub reluctor ring due to rust and debris build up on the sensor mounting surface. Hopefully someone can post the TSB, for some reason I cant copy paste it.

What is the problem with low speed ABS?

Swhitney is right. The problem is called “unintended low speed ABS activation”. There was a recall for trucks in the “rust belt”. Undo the torx screw that holds the ABS “reader” to the hub and pull it out. Put a piece of paper towel in the hole and use some emery cloth to remove the corrosion on the mounting pad.

How does the ABS system work on a GMC?

by Alibaster Smith. The ABS brake system in a GMC vehicle uses a sophisticated ABS module to sense wheel speed. If the vehicle’s wheels stop moving while brake pressure is being applied, but the vehicle itself is still moving, the system identifies this as a skid and automatically releases brake pressure to prevent the brake system from locking up.

What’s the average speed of an ABS ECU?

PS – you can check the other wheels at lower speeds of 12.4mph, but those front ones, 112.4mph ( or do they realy mean this>> 20km/h) haha! Eitherway, ithe ABS ECU thinks they are OK – Clean them and I bet ONE part of your problem is solved! Let us know! Yeah, I saw this and also laughed about 112 mph. Thanks, I’ll try to clean everything up.

Why do I have an unwanted ABS activation?

If the brakes are applied while the vehicle is traveling at a speed greater than 3.7 mph but less than 10 mph, the corrosion may cause an unwanted ABS activation. Use the following procedure to repair corrosion where the front wheel speed sensor mounts on the front wheel bearing assembly:

Why is the ABS light on on my Blazer?

ABS , (brakes), Operated erratically, (failed), in slick road conditions. 1999 Blazer, 4.3l 6 cyl. ABS failed light is on. looking for reimbursement. Abs ligh is illuminated faulty abs sensor.

How much does it cost to replace a speed sensor on a blazer?

The anti-lock brake system (ABS) front wheel speed sensors are prone to failure. When a sensor fails, the ABS warning light may illuminate and/or the ABS system may activate erratically. The average cost for a Chevrolet Blazer Wheel Speed Sensor Replacement is between $283 -$315.

Why does my car have ABS at low speeds?

The vehicle came in with the complaint that the ABS could be felt working through the brake pedal at very low speeds. I carried out a short road test to verify the complaint and, sure enough, the ABS would cut in at very low speeds; in fact, just before the car came to a stop. Apart from this the car, including the ABS system, worked as normal.

What does the ABS do at 10 mph?

The above capture was taken at about 10 mph, with the brake pedal released and with no ABS intervention. Channel A (Blue) is monitoring RH rear WSS (wheel speed sensor) and channel B (Red) monitoring LH rear WSS.

Why do we use ABS instead of ASR?

We can conclude that we are dealing with the ABS strategy rather than ASR because, quite simply, the brake pedal is being applied during the fault; this eliminates ASR and gives one less aspect to worry about.

What causes incorrect activation of ABS and ESC?

A number of factors can cause incorrect decisions, which can lead to what has been variously referred to as unintended, unwanted, incorrect or false activation of the ABS and/or ESC systems. This edition of Brake Shop will delve into several causes and cures for false activation of these systems.

Is there an ABS light during kick in?

No ABS light during kick in. Kinda weird, since on my Odyssey I never noticed anything like this (my other Camry doesn’t have ABS). Any ideas where to look at?

Why do my abs kick on when I come to a stop?

But frequently, as I pull up to a stop light or stop sign, the ABS will kick on for just about 1 second right before I come to a complete stop. Any ideas on what might cause this?

How does ABS work on a General Motors car?

General Motors is well known for ABS problems. The problem comes from the speed sensors in the wheel bearings. The sensor slips into the wheel bearing and reads a toothed wheel inside. These sensors are very senesitive to the distance between the end of the sensor and the toothed wheel.

How does ABS work on a Ford Windstar?

The ABS and traction control on a Ford Windstar helps to provide increased vehicle stability while driving. The ABS, or anti-lock braking system, helps improve driver control under hard braking. The ABS system senses wheel speed and when the wheels lock up it electronically starts pumping the brakes for you as you press and hold the brake pedal.

What causes the ABS light to go on?

This might also cause the ABS system to go active and pulse the brakes at low speeds when it is not necessary. The last bulletin describes a problem that I have not seen myself, but is listed as a common problem with 1997 through 1999 Ford F150 and F250 2 Wheel Drive models only.

What happens if you don’t have an ABS system?

If that controller gets insufficient data, or a hydraulic pump or valve isn’t responding, it illuminates the ABS warning light on the dashboard. ABS relies on a properly operating conventional brake system. If the rest of your braking system is in working order, you should usually still have normal braking without ABS.

Why does my abs kick on at a stop sign?

For whatever reason, when coming to a normal stop at a stop sign, the ABS occasionally kicks on. This is on dry pavement with good tires. It seems to only happen for the first stop after starting, so it may have something to do with temperature. I also never noticed the issue before the Winter. Any ideas of things I should check?

When do you know there is a problem with your abs light?

You know there’s a problem when the ABS light turns on right before you eat the berm at the end of the driveway You notice some strange behavior when you’re slowing down for a corner, too. When you try to make a downhill turn, you blow right past it with the wheels skidding straight and the steering wheel cranked all the way into the turn.

How to troubleshoot Chevy Silverado ABS system problems?

Remove the fuse for the ABS system with a fuse puller located in the fuse box cover. Check the fuse to make sure that it is not blown. If it is, you’ll need to replace it with another fuse of the same amperage. Look behind each wheel of the Silverado. On the back of the wheel hub are the wires for the ABS system.

Why are my base brakes not working on my Silverado?

Your base brakes will function normally but in the event of an ABS controlled stop on an “icy” or “slippery” stretch of road were the ABS system would take over to prevent a skid, that automatic system will not function. Have the vehicle scanned for trouble codes to find out which portion of the system has malfunctioned.

How can I tell if my ABS system has failed?

Check to make sure all wires are connected and are not damaged. Turn the ignition key to the “II” position and check the ABS light. The dash lights will light up initially and should then go out after a few seconds. If the ABS light stays on, then the ABS system has failed. Because the ABS system is secured to the wheel bearings,…

Where is the ABS sensor on a Chevy Silverado?

Look behind each wheel of the Silverado. On the back of the wheel hub are the wires for the ABS system. The ABS sensor sits on the wheel bearing and hub assembly, and looks like a small rectangular box. Check to make sure all wires are connected and are not damaged.

Are there any problems with the GMC Sierra 1500?

Check out our GMC Sierra 1500 overview to see the most problematic years, worst problems and most recently reported complaints with the Sierra 1500.

Why does my GM ABS brake still run?

The antilock brake system (ABS) is controlled by its own computer. When it senses a problem, the ABS module on the dashboard will light up. When the problem is fixed, the module will sometimes still stay on, and it will need to be rest.

When does the ABS activate at low speeds?