MODULE-ANTILOCK BRAKES
DESCRIPTION
NOTE: If the ABM module is replaced it must be initialized using the scan tool.
The Antilock Brake Module (ABM) (1) is mounted to the Hydraulic Control Unit (HCU) (2) and operates the ABS system.
OPERATION
NOTE: If the ABM nodule is replaced it must be initialized using the scan tool.
The ABM voltage is supplied by the ignition switch in the RUN position. The ABM contains dual microprocessors. A logic block in each microprocessor receives identical sensor signals. These signals are processed and compared simultaneously. The ABM contains a self check program that illuminates the ABS warning light when a system fault is detected. Faults are stored in a diagnostic program memory and are accessible with the scan tool. ABS faults remain in memory until cleared, or until after the vehicle is started approximately 50 times. Stored faults are not erased if the battery is disconnected.
REMOVAL
1. Remove the negative battery cable from the battery.
2. Install a brake pedal prop rod.
3. Siphon the master cylinder.
4. Disconnect the HCU electrical connectors (5).
5. Remove the primary brake line at the master cylinder.
6. Remove the primary brake line from the HCU (4).
7. Remove the secondary brake line at the master cylinder.
8. Remove the secondary brake line at the HCU (4)
9. Remove the 4 chassis lines (3) at the HCU (4).
10. Remove the 1 mounting nut and 1 bolt holding the HCU bracket attachment to the vehicle.
11. Remove the HCU (3) with the bracket (5) from the vehicle.
12. Remove the 3 ABM bolts securing the ABM (1) to the HCU (2).
13. Separate the ABM (1) from the HCU (2).
INSTALLATION
NOTE: If the ABM is being replaced with a new ABM is must be reprogrammed with the use of a scan tool.
1. Install new seals between the ABM and HCU.
2. Install the ABM (1) to the HCU (2).
3. Install the 3 ABM (1) mounting bolts to the HCU (2) if removed tighten mounting bolts to 12 N·m (9 ft. lbs.).
4. Install the HCU (3) with bracket (5) to the vehicle and tighten the 2 mounting nuts.
5. Reconnect the HCU electrical connector (5).
6. Install the 4 chassis lines (3) at the HCU (4).
7. Install the secondary brake tube at the HCU (4).
8. Install the secondary brake tube at the master cylinder.
9. Install the primary brake tube at the HCU (4).
10. Install the primary brake tube at the master cylinder.
11. Install negative battery cable to the battery.
12. Remove the brake pedal prop rod.
13. Bleed base and ABS brake systems, (Refer to 5 - BRAKES - STANDARD PROCEDURE).
14. Initialize the ABS module using the scan tool.