ABS, Traction Control, red brake lights, orange triangles or orange ABS lamps; every late model vehicle has them; in the privacy of brakes classes where everyone is a wrench we commonly referred to these warning lamps as the “check money lamp.”
Without becoming extremely technical and boring, I will attempt very simply to explain the concepts of these systems and then more importantly explain how easily they can be maintained and kept functional, savings you thousands of dollars in repairs.
To put it very simply ABS this really stands for Anti-lock Brake System, which keeps the rear brakes from locking up and putting you into a rear skid condition. Unbeknownst to most, when those rear brakes lock up, the rear wheels actually rise up off of the road surface losing the benefit of friction which actually makes the vehicle speedup.
Originally the first types of ABS systems were called single channel systems where upon the wheel sensor was in the rear differential housing or in the transmission rear extension housing. By monitoring the speed of the drive shaft, the ABS controller could control of the rear brakes of the vehicle as a single unit.
With the introduction of independent suspensions it became obvious that each wheel will have to be controlled independently. By installing a speed sensor on each rear wheel, the ABS controller would be able to monitor each of the rear wheels independently. This was the beginning of two channel ABS systems. Shortly after many trucks that were straight axle units came into service with 3 channel ABS systems which had a wheel speed sensor on each front wheel and a single sensor in the rear differential.
Finally we have 4 channel ABS. which has a speed sensor on each wheel. This system has developed into a most functional system which not only can stop a lock up situation, but also a wheel that has lost traction on acceleration, monitors and becomes a redundant odometer, and cruise control and air bag confirmation point.
Antilock brakes monitor the rotational speed of every tire when the brakes are applied.
If and when one or multiple wheels slow down far faster than the others the ABS controller then releases the brake pressure to each of these wheels. This is done by preventing the fluid pressure to each of these wheels for micro seconds at a time allowing the locked up wheel or wheels to momentarily turn so as to be able to control the braking event.
This allows the driver to have a controlled yet quick braking event, without losing control of the vehicle. The only difference to the driver is that they would feel a rapidly pulsating brake pedal as the skid is kept under control. When the wheel speeds normalize the pulsation goes away.
Traction control is Antilock in reverse. When the controller senses that upon acceleration one or more wheels is turning faster than designed the Traction Control /ABS controller actually applies the brakes to slow those wheels down. So for all of you old gear heads “leaving rubber” will never happen again.
As so far as the redundant monitoring for the speedometer, cruise control and air bags, just think of it in this vein. As the transmission is running and sending data to the transmission control module, if this information becomes corrupted the Powertrain Control Module can refer back to the ABS controller to decide if the vehicle or trans control system is at fault.
Likewise if the airbag impact sensor registers an impact the PCM will look back to the trans control for a rapid deceleration , the ABS system for a rapidly slowing wheel speeds or even lock ups, and finally to see if the brake lights are on before it will detonate the air bag. This and more happens in less than 500micro seconds.
Now that we can understand why it works I can tell you how it works. It’s all pretty simple; built within the circuitry is an external pump, which takes control away from the driver’s foot. It sends or removes pressure to the ABS control unit’s hydraulic circuit. Inside this controller are a series of “dithering” valves and solenoids that have the ability to turn on or off in as many times as 32 times a second. This valving is what applies or removes the brake pressure to the wheels.
Given the complexity of these systems there are only 2 things that have the ability to run through these components; they are brake fluid and electrons!
The average cost of the hydraulic portion of the controller is usually between $1500.00 to $2500.00. The electronic portions of the controllers are pretty stable at about $900.00 plus labor and diagnostic testing.
Preventively the cost of flushing your brakes hydraulic system once every 2 years is about $126.00 and replacing your battery before it goes dead is about $175.00. So when your service provider says that you should have your brake fluid flushed every 2 years no matter how many miles have been driven think of this “$126.00 or $1200.00.
So for the bazillionth time I end this story with PREVENTIVE MAINTENANCE REDUCES DOWNTIME AND THE COST OF OWNERSHIP” AND PREVENTIVE MAINTENANCE BEGINS AT MILE 00001.
Don’t forget that during the month of October we are working in conjunction with WAGNER BRAKES and we are providing front or rear pads or shoes at no cost to you the consumer during our PUTTING THE BRAKES ON AUTISM campaign after which we will donate 10% of all the brake work we provide to HARBOUR HEIGHTS CHARITIES for all of the great work they do for the Autistic children in this county.
236 S. Tamiami Tr.
Punta Gorda, Fl. 33950
Auto Repair, A/C Repair, Oil Change, Brake Repair & Transmission Services