Diagnostic Procedures Overview

IMPORTANT INFORMATION
Follow the diagnostic procedures step-by-step in order as indicated within the diagnostic tests.
- The ABS control module CANNOT recognize some failures; therefore if a concern exists and no Diagnostic Trouble Code's (DTC)'s are stored by the ABS control module, other diagnostic steps must be followed.
- The ABS control module cannot store a DTC if it is not supplied battery positive voltage (B+). This condition can be found by using the Quick Test Check Sheet.
- Following the wrong sequence or bypassing diagnostic steps will lead to unnecessary replacement of parts and/or incorrect resolution of the symptom.

DATA LINK DIAGNOSTICS
The diagnostic procedure consists of four sections:
- On-Board Diagnostics.
- Quick Tests. Pinout Values and Diagnostic Parameters
- Anti-Lock Warning Indicator Symptom Chart. Symptom Related Diagnostic Procedures
- Diagnostic Tests. Diagnostic Trouble Code Descriptions

ON-BOARD DIAGNOSTICS
The ABS control module is capable of performing an on-board diagnostic using Rotunda Super Star II Tester or equivalent. The ABS control module monitors system operation and can store all defined DTCs in its memory. It is important to understand the ABS control module cannot recognize some failures, therefore, if a symptom exists and no DTCs are stored by the ABS control module, other diagnostic steps must be followed.

No Codes - The ABS control module cannot store a DTC if there is no power to the ABS control module. This condition can be found by using the Anti-Lock Quick Check Sheet.

DTCs 18, 19 And 20 Series Codes - will override any other stored codes and will not allow other codes to be output if the failure exists while the on-board diagnostic is being run. If the failure is intermittent or if the code was left in the ABS control module due to improper erasing procedures, the code will be output during on-board diagnostics, but the next code will also be output.

TEST EQUIPMENT
The following equipment or an equivalent, is recommended for diagnosing ABS:
- Rotunda Anti-Lock Breakout Box Adapter.
- Rotunda EEC-IV 60-Pin Breakout Box.
- Rotunda 73 Digital Multimeter.
- Rotunda Super Star Tester II.
- Rotunda New Generation Star (NGS) Tester.
- Rotunda Service Bay Diagnostic System (SBDS)(r) may also be used instead of the NGS to diagnose this system.