Antilock Brakes / Traction Control Systems: Service and Repair

NOTES:
^ When any part of the hydraulic system has been disconnected for service or replacement, air may enter the system causing a spongy pedal action. Bleed the hydraulic system after it has been properly connected to make sure that all air is expelled.
^ Anytime service is performed on the ABS valve block or pump and motor assembly, a special bleed procedure must be followed to make sure no air is trapped in the ABS control and modulator assembly. If this procedure is not done, the customer could experience a spongy pedal after they actuate the ABS.
^ Use Rotunda New Generation Star (NGS) Tester or equivalent scan tool.

ABS SYSTEM BLEEDING
1. Bleed entire system conventionally using a manual or pressure bleed procedure as described.
2. Hook up scan tool to the serial data link connector (DLC) below the instrument panel as if retrieving Diagnostic Trouble Codes (DTC)s.
3. Make sure ignition switch is in the "RUN" position.
4. Follow instructions on the NGS screen. Choose correct vehicle and model year, go to "Diagnostic Data Link" menu item, choose ABS Module, choose "Function Tests", and then choose "Service Bleed".
5. The NGS will prompt you to apply the brake pedal. Make sure you push hard on the brake pedal. You will need to hold down the brake pedal for approximately 5 seconds while the NGS opens the outlet valves in the brake pressure control valve block. When the outlet valves are opened, you should immediately feel the pedal drop. Make sure you push the pedal all the way to the floor (very important). The NGS will then instruct you to release the brake pedal. After you release the brake pedal, the NGS will run the ABS hydraulic pump motor for approximately 15 seconds.
6. Repeat Step 5 to make sure all air is flushed from the ABS unit. Upon completion, the NGS will display "Service Bleed Procedure Completed".
7. Repeat the conventional system bleed using a manual or pressure bleed procedure as described.