ABS / Air Bag 2004 User Guide
Autobleed Test, Automated Bleed, or Service Bleed
The bleed tests remove air from the internal brake fluid chambers after servicing the brakes. For some vehi- cles, the NGIS tool runs the test automatically; for other vehicles, the tool displays instructional screens for you to perform the test manually.
The test usually cycles the valve solenoids so you can use brake pedal feel to diagnose solenoid problems, pump output problems, and pedal feel complaints. The final phase of the test releases brake pressure from each hydraulic channel in sequence, allowing you to identify pedal travel problems, solenoid leakage, or internal problems.
IMPORTANT:
•Before bleeding the brake system, make sure no diag- nostic codes are present.
•Do not let the master cylinder run dry during the brake bleeding procedure.
•Do not allow brake fluid to contact the motor pack or the electrical connectors.
IMPORTANT: Use a recommended brake fluid, do not use silicone brake fluids in an ABS- equipped vehicle.
WARNING: After bleeding the brake system, check the brake pedal for excessive travel or a “spongy” feel. Bleed again if either condition is present.
Chapter 10: Special Tests
Special Test Descriptions
Function Test
The Function Test automatically commands the ABS relay, valve solenoids, and pump motor on and off to test for proper operation. If there is a malfunction, a diagnostic trouble code (DTC) is set in the vehicle.
Gear Tension Relief Test
The Gear Tension Relief Test relieves tension from the ABS motor gears so you can separate the ABS motor pack from the ABS hydraulic modulator.
For some vehicles, the NGIS tool runs the test auto- matically; for other vehicles, the tool displays instructional screens for you to perform the test manually.
Hydraulic Control Tests
The Hydraulic Control Tests let you use the NGIS tool to manually engage and disengage the ABS solenoids for troubleshooting the hydraulic functions.
Idle Up Manual Control Test
The Idle Up Tests let you use the NGIS tool to manually control the idle up actuators.
Lamp Tests
The Lamp Tests lets you use the NGIS tool to manually control the ABS or TCS warning or indicator lamps.
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Automated Test
The Automated Test automatically commands each solenoid valve and the pump motor on and off to test for proper operation. If there is a malfunction, a diag- nostic trouble code (DTC) is set in the vehicle.
Brake Bleed Preparation Test
The Brake Bleed Preparation Test prepares the brake lines for bleeding by clearing air from the modulator. The test rehomes all the ABS and TCS motors, cycles the TCS motors, and then returns all motors to the “home” position at the bottom of the bore.
Usually, the tool displays instructional screens for you to perform the test manually
Manual Control Test
See “ABS Manual Control Tests” on page 62.
