Tools Required
Scan Tool
A scan tool when plugged into the OBD2 Data Link Connector (DLC) becomes
part of the vehicle electronic system. The scan tool performs the following
functions:
| • | Display a Current Diagnostic Trouble Code (DTC). |
| • | Display History Diagnostic Trouble Codes (DTCs). |
| • | Display Captured Data for the last DTC set. |
| • | Display ABS input and or output data. |
| • | Control ABS components. |
| • | Perform extensive ABS diagnosis. |
Each test mode has specific diagnosis capabilities which depend upon
the type of scan tool used. When using a scan tool there are four main selections
for diagnosing the ABS:
| • | Diagnostic Trouble Codes (DTCs): DTC Information (Current DTC,
History DTC), Capture Data and Clear DTC Information. |
| • | Data List -- Displays wheel speed data, stoplamp switch status,
ABS status, solenoid valves and pump motor command and/or monitor status. |
| • | Snapshot -- In this test mode, the scan tool captures data
on a specific or any DTC setting. |
| • | Special Functions -- Performs various functional tests to
assist in problem isolation during troubleshooting. |
Special Functions
Auto Bleed Procedure
The Auto Bleed Procedure is used to provide a complete brake system
bleed on ABS equipped vehicles. The procedure cycles the system valves and
runs the pump to purge air from secondary circuits normally closed off during
non-ABS mode operation and bleeding. It is to be used when it is suspected
that air has been ingested into the system secondary circuits, or when the
Brake Pressure Modulator Valve (BPMV) has been replaced with a new unit.
Lamp Test
The lamp test allows activation of the "ABS" lamp in the
Instrument Cluster to aid in diagnosing lamp malfunctions.
Solenoid Tests
This test indicates whether specific valves in the BPMV release wheel
cylinder pressure from assigned hydraulic wheel circuits.
Pump Motor Test
This test runs the pump motor to apply fluid pressure to specified wheel
circuits.
