Whenever service is performed to the Hydraulic Control Unit, a specific procedure must be performed to bleed the system to ensure that no air is trapped in the HCU.
To perform this procedure, the New Generation Start (NGS) Tester, or an equivalent brake tool, is necessary.
- Bleed the entire hydraulic system using the same procedure used for a non-ABS system. (Refer to the brake bleeding procedure, earlier in this section.)
- Attach the NGS tester to the underdash serial link connector, as though retrieving engine trouble codes.
- Turn the ignition switch to the RUN position.
- Follow the instructions on the NGS screen. Choose the correct vehicle and model year, then go to the "Diagnostic Data Link" menu item. Choose the ABS module, then "Function Tests" and "Service Bleed."
- The NGS will instruct you to depress the brake pedal. Ensure that you push hard on the pedal. The pedal must be held down for approximately 5 seconds while the NGS opens the outlet valves in the HCU. When the outlet valves open, the brake pedal should immediately drop; make sure to depress the brake pedal all the way to the floor. This is VERY important to do!
- The NGS will then prompt you to release the pedal. After the pedal is released, the NGS will run the ABS hydraulic pump motor for approximately 15 seconds.
- Repeat Step 5 to ensure that all air has been flushed from the HCU. Upon completion, the NGS will show the "Service Bleed Procedure Completed" message.
- Once again, bleed the rest of the hydraulic system as for a non-ABS model.