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.
- 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 under dash Data Link Connector (DLC), as though retrieving engine trouble codes.
- Turn the ignition switch to the RUN position.
- Follow the instructions on the scan tool 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 scan tool 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 scan tool 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 scan tool will then prompt you to release the pedal. After the pedal is released, the scan tool 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 scan tool will show the -Service Bleed Procedure Completed- message.
- Once again, bleed the rest of the hydraulic system as for a non-ABS model.