How to Replace a car ABS Controller
The ABS controller is responsible for limiting the brake line pressure to allow the tire or tires to start rotating at an equal rate as the remaining wheels. If the controller fails or malfunctions it can cause the ABS system to stop working. If this condition has occurred thebrake system warning light should be illuminated or blink while the car is in operation. There are several ways to troubleshoot an ABS system depending on the manufacturer if the system your car is equipped with.
Most ABS diagnostic systems can be access by the ALDL connector much like the body or engine control system. Using a trouble code reader with the capability to read such codes should be connected with the ignition key in the "on" position. Once a trouble code that confirms the controller failure remove the battery cable from the negative side of the battery. be sure to wear protective gloves, eyewear and clothing. Now we can begin the ABS controller replacement.
Before you begin place your car on level ground with theemergency brake on (unless checking the rear ABS sensor)
Step 1 - With the car on level ground and the ignition key in the "off" position depress the brake pedal about 15 times, this will deplete the system from an residual line pressure.
Step 2 - Locate the ABS controller, usually under the hood of the car or on the frame rail.
Step 3 - Remove metal or plastic shields to gain clear access to the control unit.
Step 4 - Disconnect electrical connectors from controller
Step 5 - Using a brake line wrench remove all brake lines from the controller.
Step 6 - Remove all controller mounting bolts and remove the unit.
Step 7 - Match the replacement controller to the one just removed from the car. The replacement unit should be an "exact" match
Step 8 - Now install the new unit by reattaching the mounting bolts.
Step 9 - Reconnect all brake lines (note: make sure all line flare connection are free from dirt and debris to ensure a leak free seal)
Step 10 - Reconnect the wiring connectors (note: some connector are featured with dielectric grease, this is normal do not clean out this grease for it is used as a rust inhibitor)
Step 11 - Reinstall dust/dirt shields and covers
Step 12 - Remove thebrake master cylinder fluid cap
Step 13 - Open all brake caliper brake system bleeders and allow the brake fluid to flow until no air bubbles are observed. Then close thebrake bleeders.
Step 14 - Refill the brake master cylinders fluid level to the normal operating position and reinstall the cap.
Step 15 - With the ignition key in the "on" position without the engine running, re-attach the scan tool to clear all trouble codes the system has stored.
Step 16 - Now start the engine and depress the brake pedal several times. The brake pedal's operation should feel normal and ABS system warning light should stay out.
Step 17 - Never operated a car unless normal brake operation is present