|
|||||||
|
|
|
|||||
|
|
|||||||
|
Antilock braking systems (ABS) have had more of an impact on brake servicing than may seem obvious. And although most jobs are routine and your customer leaves satisfied, on occasion somebody will come back in to your shop with a complaint. The most successful technicians have mastered the art of quick – but complete – installations. Most comebacks aren’t the result of something intentionally done wrong, but may be caused by something being overlooked. I get the following call at least once a day: “I just did a routine front brake reline and now the car’s: ABS light is on. Brake pedal is low. Brakes are dragging. Pulling to the left/right.” These problems can be avoided by adopting some simple and very effective practices when performing brake service on an ABS-equipped vehicle. The number one cause on these problems is very simple, and to prevent it from happening, technicians need to modify the way they are currently doing a brake job. It is extremely important to open the bleeder screw when compressing caliper pistons or wheel cylinders during routine brake maintenance. When a caliper piston is pushed in, brake fluid gets forced backward, up into the system. Since the caliper is the lowest point in the system, dirt and corrosion naturally accumulate there. When this grime and dirt finds its way into the HCU portion of the ABS system, it can cause valves to stick. This can lead to: a vehicle pulling one way or another; accumulators sticking open, which leads to low pedal; compensator ports pluging, which leads to dragging brakes; and of course, it can make the ABS light come on due to all of the above. If technicians get in the habit of opening the bleeder when they compress the caliper piston, as well as selling customers a brake fluid flush, these problems will more than likely be prevented. Another problem that concerns installers is when the ABS applies itself at low speed. Wheel speed sensors are magnetic. They can collect large amounts of debris from the road. Freshly turned rotors also can leave metal filings on the sensors, especially if an on-car brake lathe is used. The Honda Motor Co. actually recommends removing the sensors during rotor machining. We suggest cleaning the wheel speed sensors and tone rings during a brake job. This can help prevent false signals that can actuate the ABS system during low speed stops. Brake technology, like everything else automotive, is changing constantly. By keeping up on changes like these, you’re likely to avoid unneeded comebacks. |
