Test 1A - Checking For Diagnostic Trouble Codes

PROCEDURE
1. Your diagnostic test procedure must begin with a thorough visual inspection of the ABS system for damaged components or disconnected connectors. The brake lamps must be operational and if they are not, repair them prior to continuing.
2. Connect the DRB to the data link connector located under the dash to the right of the steering column. If the DRB does not power up, check the power and ground supplies to the connector
3. Select "Anti-lock Brakes". Turn the ignition on. If the DRB displays "No Response", perform test 25A.
4. Read and record all ABS diagnostic trouble codes. If the "Valve Power Feed Circuit" trouble code is present, it must be repaired prior the addressing any other DTC's. If any additional codes are present, proceed to the appropriate test.
5. If there are no trouble codes present, refer to the SYSTEM TESTS contained in TEST 1B.

NOTE: The DRB must not be connected to the data link connector when road testing for proper antilock operation.

6. If no other problems are found, it will be necessary to road test the vehicle. The system is disabled while in diagnostic mode. Perform several antilock stops from above 50 km/h (30 mph) and then repeat steps 2, 3, and 4. If any trouble codes are present, proceed to the appropriate test.
7. The following conditions should be considered "NORMAL" operation, and no repairs should be attempted to correct them.

^ Brake pedal feedback during an ABS stop (clicking, vibrating)
^ Clicking, groaning or buzzing at 12 km/h (7 mph) (drive off self test)
^ Groaning noise during an ABS stop
^ Slight brake pedal drop and pop noise when ignition is initially turned on
^ Brake pedal ratcheting down at the end of an ABS stop

8. If the complaint is ABS "cycling" at the end of a stop at low speeds, it may be caused by a marginal wheel speed sensor signal. The sensor air gap, tone wheel condition, and or brakes hanging up are possible causes to this condition.

DRB DIAGNOSTIC TROUBLE CODE DISPLAYED DIAGNOSTIC TEST
ABS Warning Lamp Circuit Failure 2ATest 2A - ABS Warning Lamp Circuit
Diagnostic Compare 3ATest 3A - Diagnostic Compare
Left Front Inlet Valve 4ATest 4A - Inlet Valve Circuits
Left Front Outlet Valve 5ATest 5A - Outlet Valve Circuit
Left Front Sensor Circuit Failure 6ATest 6A - Wheel Speed Sensor Circuit Failure
Left Front Sensor Continuity <25 Mph 7ATest 7A - Left Front Wheel Speed Sensor Continuity Fault
Left Front Sensor Continuity >25 Mph 7A
Left Front Sensor Signal Missing 11ATest 11A - Left Front Sensor Signal Missing/Comparison
Left Front Sensor Speed Comparison 11A
Left Rear Inlet Valve 4A
Left Rear Outlet Valve 5A
Left Rear Sensor Circuit Failure 6A
Left Rear Sensor Continuity <25 Mph 8ATest 8A - Left Rear Wheel Speed Sensor Continuity Fault
Left Rear Sensor Continuity >25 Mph 8A
Left Rear Sensor Signal Missing 12ATest 12A - Left Rear Sensor Signal Missing/Comparison
Left Rear Sensor Speed Comparison 12A
Pump Motor Circuit Not Working Properly 15ATest 15A
Pump Motor Not Running 16ATest 16 - Pump Motor Not Running
Right Front Inlet Valve 4A
Right Front Outlet Valve 5A
Right Front Sensor Circuit Failure 6A
Right Front Sensor Continuity <25 Mph 9ATest 9A - Right Front Wheel Speed Sensor Continuity Fault
Right Front Sensor Continuity>25 Mph 9A
Right Front Sensor Signal Missing 13ATest 13A - Right Front Sensor Signal Missing/Comparison
Right Front Sensor Speed Comparison 13A
Right Rear Inlet Valve 4A
Right Rear Outlet Valve 5A
Right Rear Sensor Circuit Failure 6A
Right Rear Sensor Continuity <25 Mph 10ATest 10A - Right Rear Wheel Speed Sensor Continuity Fault
Right Rear Sensor Continuity >25 Mph 10A
Right Rear Sensor Signal Missing 14ATest 14A - Right Rear Sensor Signal Missing/Comparison
Right Rear Sensor Speed Comparison 14A
System Overvoltage 17ATest 17A - System Overvoltage
System Undervoltage 18ATest 18A - System Undervoltage
Valve Block Feed Failure 19ATest 19A - Valve Block Feed Failure
Valve Power Feed Circuit 20ATest 20A
Traction Control Valve #1 21ATest 21A - Traction Control Valve Circuits
Traction Control Valve #2 21A