Inspection Procedure 3: The system is not turned on and off by operating the blind spot warning switch: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB992006: Extra Fine Probe

1. STEP 1. Using scan tool (M.U.T.-III) other system data list 

   Using the gateway-ECU data list, check the blind spot warning switch signal.

   CAUTION: To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).

   Connect scan tool MB991958. Refer to DIAGNOSIS ."

   • When the blind spot warning switch is pressed.

     Item No.	Item name	Normal condition
     Item 5	BSW switch	ON

   • When the blind spot warning switch is not pressed.

     Item No.	Item name	Normal condition
     Item 5	BSW switch	OFF

   OK: Normal condition is displayed. 

   Q: Is the check result normal? 

   YES  : Go to Step  7.

   NO  : Go to Step 2.

2. STEP 2. Connectors check: gateway-ECU connector C-49, blind spot warning switch connector C-50 

   Q: Are gateway-ECU connector C-49, blind spot warning switch connector C-50 in good condition? 

   YES  : Go to Step 3.

   NO  : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

3. STEP 3. Check the wiring harness between gateway-ECU connector C-49 (terminal No. 21) and blind spot warning switch connector C-50 (terminal No. 3). 
   • Check the input signal line for ground circuit and open circuit.

   Q: Is the wiring harness between gateway-ECU connector C-49 (terminal No. 21) and blind spot warning switch connector C-50 (terminal No. 3) in good condition? 

   YES  : Go to Step 4.

   NO  : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

4. STEP 4. Check the wiring harness between blind spot warning switch connector C-50 (terminal No. 4) and body ground. 
   • Check the ground line for open circuit.

   Q: Is the wiring harness between blind spot warning switch connector C-50 (terminal No. 4) and body ground in good condition? 

   YES  : Go to Step 5.

   NO  : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

5. STEP 5. Blind spot warning switch check 

   Refer to BLIND SPOT WARNING SWITCH  .

   Q: Is the check result normal? 

   YES  : Go to Step 6.

   NO  : Replace the blind spot warning switch.

6. STEP 6. Using scan tool (M.U.T.-III) other system data list 

   Using the gateway-ECU data list, check the blind spot warning switch signal.

   • When the blind spot warning switch is pressed.

     Item No.	Item name	Normal condition
     Item 5	BSW switch	ON

   • When the blind spot warning switch is not pressed.

     Item No.	Item name	Normal condition
     Item 5	BSW switch	OFF

   OK: Normal condition is displayed. 

   Q: Is the check result normal? 

   YES  : Go to Step 7.

   NO  : Replace the gateway-ECU.

7. STEP 7. Retest the system 

   Check whether the system can be switched on and off by the blind spot warning switch.

   Q: Is the check result normal? 

   YES  : Intermittent malfunction is suspected (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).

   NO  : Replace the BSW-ECU (master).