The earliest versions have no memory and will only display a code while the ABS lamp is lit. In this case, after the car is driven, don’t turn the key off until the code is retrieved. Using your service information, locate the ABS control unit. Count out the code from the LED in the control unit. This system will save only one code. Deal with the code displayed and road test the car to check for others. There are too many code definitions to list here, so it will be necessary for you to consult your service information system. As always, the code will send you in the right direction, but it’s up to you to perform the final diagnostic steps to confirm whether the problem is a bad part or a circuit-related issue.
On early cars, the codes are self-clearing, so no ABS lamp means no codes. Later models require that the codes be cleared. To do this, turn on the key and use the jumper wire we grounded to get the codes. Ground the jumper for one second and disconnect it, then repeat the process twice more in a 12-second period, grounding the jumper for at least one second each time. The ABS lamp will be illuminated during the process, but should go out when completed. Confirm that the codes have been cleared by checking for codes but getting only the system’s normal code 12.
I’ve mentioned a couple of times that ABS has changed the way we service brake systems. The most important change is that the quality of the fluid in the system is critical. It’s no longer acceptable to pull fluid out of the reservoir and simply push in the caliper pistons, moving all that dirty fluid back though the ABS actuator.
We also talked earlier about the brakes dragging as result of pressure buildup in the system. With the small orifices in the ABS unit, it doesn’t take much debris to cause a restriction in the valves that would prevent fluid from returning to the master cylinder when the brakes are released. As the temperature of the fluid increases, the pressure will increase while applying the brake, causing the problems we talked about.
I’ve never heard of anyone who has had any success flushing an ABS unit that has been contaminated. Replacement of this expensive unit is the only alternative. It’s an unfortunate situation for the customer, and an even worse one for the shop that did the job. The way to avoid this problem is to always open the bleeders while the pistons are retracted, using a bleeder bottle to catch the fluid. There’s no reason not to get into this habit.
At this point, I wouldn’t think you would consider a brake job complete without bleeding and flushing the system. Although brake fluid changes have always been a recommended service that was often overlooked, it shouldn’t have been. With the widespread use of ABS and the longevity that these vehicles enjoy, it’s foolish not to at least flush the system when brake service is performed.
For some of you, this article covered things that are second nature, but I believe it’s the basics that set the tone for a shop. Good work habits that start with handling the customer at the service desk, to making sure every car gets a basic safety check, are the things that will set your shop apart from the guy down the street.
