Diagnosis

DIAGNOSIS
1. Your diagnostic test procedure must begin with a thorough visual inspection of the system components for damage and for disconnected connectors. A visual inspection consists of physically looking for the possible cause of a malfunction. A careful and thorough visual inspection of components may quickly identify the cause of a malfunction and eliminate the need for diagnostic testing.

PERFORM THE FOLLOWING VISUAL INSPECTIONS BEFORE DOING ANY DIAGNOSTIC TESTING. If a malfunction is not resolved by the visual inspection, proceed with diagnostic testing according to the instructions in the manual.

Brake Fluid Level
Visually inspect for the proper fluid level within the fluid reservoir.

Hydraulic Control Unit
Visually inspect the hydraulic as assemblies for leaks and for damaged or disconnected connectors.

Fuses
Visually inspect that all fuses are properly installed.

Wheel Speed Sensor Connectors
Visually inspect both front wheel speed sensor connectors for damage or disconnection. Inspect the rear axle speed sensor connectors.

Brake Fluid Lines
Visually inspect brake fluid lines for any leaks or damage.

Wheel Speed Sensors
Visually inspect all wheel speed sensor(s) and tone wheel(s) for any damage.

Controller Antilock Brake (CAB)
Visually inspect the CAB for a secure mounting and the CAB connecttor for damage or loose connection.

Base Brake System
Visually inspect the condition of the parking brake, rotors, drums, and calipers.

2. Connect the DRBIII to the Data Link Connector (DLC).
3. With the DRBIII, read active and stored trouble codes and record them. If you encounter a "NO RESPONSE" message on the DRBIII while accessing diagnostic menu, perform DRBIII No Response Message test. For other DRBIII related communication problems, refer to the Vehicle Communications test in the Body and Frame. Using the DRBIII, either reset the module to erase all stored trouble codes or use the erase command after reading all diagnostic trouble codes.
4. Turn ignition off, then on. If the diagnostic trouble code doesn't come back, refer to the diagnostic trouble code description. If the DRBIII displays diagnostic trouble codes, proceed to the appropriate diagnostic tests). If no diagnostic trouble codes are present at the time, perform the System Verification Test.

WARNING: Before performing any road test, verify that full braking capability is present.