Test 1A - Checking For Diagnostic Trouble Codes

1. The diagnostic test procedure must begin with a thorough visual inspection of the Antilock Brake System (ABS). Inspect connectors and components for damage and/or proper connection. The brake lamp circuit also provides an input to the ABS System. If the brake lamps do not operate, they must be repaired.

2. Connect the Diagnostic Read-Out Box (DRB) to the Diagnostic Connector.
^ If the DRB screen is blank, perform Test 18A. Test 18A - DRB Blank Screen

^ If there is an error message on the DRB screen, refer to the DRB user's guide.

3. Turn the ignition on. With the DRB, select ABS.
^ If the DRB Shows "No Response", perform Test 17A. Test 17A - DRB "No Response" Message

4. GWith the DRB, select "Inputs/Outputs" and read the brake switch status. While pressing on the brake pedal, observe the DRB display.
^ If the brake switch status does not reflect the proper state of the brake pedal, perform Test 19A. Test 19A - Checking Brake Lamp Switch Input to CAB

5. If no trouble codes are found perform Test VER2A. Verification Test VER-2A - (Road Test) - ABS