Inspection Procedure 7: ABS system inoperative: Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: M.U.T.-III USB Cable
  • MB991910: M.U.T.-III Main Harness A

1. STEP 1. Using scan tool MB991958, diagnose the CAN bus line. 

   Use scan tool to diagnose the CAN bus lines.

   Q: Is the check result normal? 

   1. YES:  Go to Step 2.
   2. NO:  Repair the CAN bus lines (Refer to CAN BUS DIAGNOSTICS TABLE ). On completion, go to Step 2.
2. STEP 2. DTC check after resetting CAN bus lines 

   Q: Is any DTC set? 

   1. YES:  Carry out the relevant troubleshooting (Refer to DIAGNOSTIC TROUBLE CODE CHART  ).
   2. NO:  Go to Step 3.
3. STEP 3. Hydraulic unit (integrated with ABS-ECU) check 

   Refer to HYDRAULIC UNIT CHECK  .

   Q: Is the check result normal? 

   1. YES:  Go to Step 4.
   2. NO:  Repair the brake pipe or replace the hydraulic unit (integrated with ABS-ECU) (Refer to HYDRAULIC UNIT  ).
4. STEP 4. Operation check 

   Q: Does ABS operate normally? 

   1. YES:  The procedure is complete.
   2. NO:  Check the brake system related components except the ABS system.