Diagnostic Procedures

Take a systematic approach. The seven step procedure is recommended to get the job done quickly and correctly.

Step # 1: Verify the customer's complaint. Determine whether the complaint applies to the ABS system or the car's service brake system.

Step # 2: Eliminate the obvious. Make a quick visual inspection: master cylinder fluid level, obvious fluid leakage, damaged wires or loose connectors. Be especially alert for evidence of previous repair attempts, accidents, installations of alarm systems, sound systems, or other electrical system changes or repairs that may have affected ABS wiring or connectors.

Step # 3: Be sure the generator is charging and the battery is not low. The ABS draws a lot of current during its self test, and a subnormal electrical system can cause the ABS light to come on. Low generator output can also trigger Diagnostic Trouble Codes (DTCs).

Step # 4: Using the scan tool (MUT II), check and record all ABS DTCs.

Note: Turn ignition OFF before connecting or disconnecting the scan tool!

Step # 5: Road test the vehicle with the ABS in operation. Then pull the fusible link that powers the ABS and retest the vehicle. By now you should know whether the complaint relates to the vehicle's normal braking system or the ABS. Once ABS is confirmed as the cause, reinstall the fuse and proceed to Step # 6.

Step # 6: Using the diagnostic information in this bulletin and the proper service manual, take the indicated corrective action. If you are uncertain about any diagnostic results you have obtained, please call the MMSA Tech Line 1-800-446-6064.

Step # 7: Perform a system performance test to verify that it operates properly before returning the vehicle to the customer.