Inspection Procedure 3: ABS warning light does not illuminate when ignition switch is turned to the ON position (engine stopped): 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 ). Then go to  Step 9.
2. STEP 2. Using scan tool MB991958, check the DTC 

   Use scan tool to check the DTC for the ABS system.

   Q: Is the DTC set? 

   1. YES:  Carry out the diagnosis for the DTC. (Refer to DIAGNOSTIC TROUBLE CODE CHART  .)
   2. NO:  Go to Step 3.
3. STEP 3. Using scan tool MB991958, check the actuator test 

   Perform the following actuator test by the combination meter system, and check if the ABS warning light illuminates (Refer to Combination Meter/ ACTUATOR TEST TABLE ).

   • Item No. 07: Indicator 1

   Q: Is the check result normal? 

   1. YES:  Go to Step 4.
   2. NO:  Troubleshoot the combination meter (Refer to Combination Meter - TROUBLE SYMPTOM CHART ). Then go to  Step 9.
4. STEP 4. Check coding data 

   Use scan tool to check if coding data stored in ETACS-ECU is normal (Refer to CODING LIST ).

   Q: Is the check result normal? 

   1. YES:  Go to  Step 6.
   2. NO:  Go to Step 5.
5. STEP 5. ETACS-ECU variant coding 

   Perform the variant coding to the ETACS-ECU.

   Q: Does variant coding succeed? 

   1. YES:  Go to  Step 9.
   2. NO:  Replace the ETACS-ECU (Refer to ETACS-ECU ), and then go to  Step 9.
6. STEP 6. Scan tool other system DTC 

   Using scan tool, check that the DTC U0141 is not set by the combination meter system.

   Q: Is the DTC set? 

   1. YES:  Troubleshoot the combination meter (Refer to Combination Meter - DTC U0141: ETACS CAN TIMEOUT ), and then go to  Step 9.
   2. NO:  Go to Step 7.
7. STEP 7. Scan tool other system DTC 

   Using scan tool, check that the DTC U0121 is not set by the ETACS system.

   Q: Is the DTC set? 

   1. YES:  Troubleshoot the ETACS-ECU (Refer to ETACS - DTC U0121: ASC-ECU CAN TIMEOUT ), and then go to  Step 9.
   2. NO:  Go to Step 8.
8. STEP 8. Retest the system. 

   Q: Does the ABS warning light turn ON and OFF normally? 

   1. YES:  Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
   2. NO:  Replace the hydraulic unit (integrated with ABS-ECU) (Refer to HYDRAULIC UNIT  ). Then go to Step 9.
9. STEP 9. Retest the system. 

   Q: Does the ABS warning light turn ON and OFF normally? 

   1. YES:  The procedure is complete.
   2. NO:  Return to  Step 1.