Inspection Procedure 3: The position of the combiner display area cannot be adjusted even if the angle adjustment switch is operated: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB992006: Extra Fine Probe

1. STEP 1. Resistance measurement at HUD connector (BR+, BR-, SW- terminal). 
   1. Disconnect the HUD and HUD switch connector, and measure at the wiring harness side.
   2. Measure the resistance between the HUD connector (BR+) and HUD switch connector terminal No. 3

      OK: The resistance should be 2 ohms or less 

   3. Measure the resistance between the HUD connector (BR-) and HUD switch connector terminal No. 9

      OK: The resistance should be 2 ohms or less 

   4. Measure the resistance between the HUD connector (SW-) and HUD switch connector terminal No. 11

      OK: The resistance should be 2 ohms or less 

   Q: Is the check result normal? 

   YES:  Go to Step  2.

   NO:  Correct the circuit between the HUD connector and HUD switch connector (BR+, BR- or SW- terminal).

2. STEP 2. Check the HUD switch. 

   Check the input signal of the brightness adjustment switch (+/-) by using the service data of the HUD.

   • terminal No. 3 - 11
   • terminal No. 9 - 11

   Q: Is the check result normal? 

   YES:  Go to Step  3.

   NO:  Replace the HUD switch.

3. STEP 3. Using scan tool (M.U.T.-IIISE), check data list. 

   Check the input signal of the brightness adjustment switch (+/-) by using the service data of the HUD.

   CAUTION: To prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
   1. Connect scan tool (M.U.T.-IIISE). Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) ."
   2. Turn the ignition switch to the "ON" position.
      • When the brightness adjustment switch (+) is operated.

        Item No.	Item name	Normal condition
        2	Brightness SW (UP)	ON

      • When the brightness adjustment switch (+) is not operated.

        Item No.	Item name	Normal condition
        2	Brightness SW (UP)	OFF

      • When the brightness adjustment switch (-) is operated.

        Item No.	Item name	Normal condition
        3	Brightness SW (DOWN)	ON

      • When the brightness switch (-) is not operated.

        Item No.	Item name	Normal condition
        3	Brightness SW (DOWN)	OFF

        OK: Normal conditions are displayed for all the items. 

      Q: Is the check result normal? 

      YES:  Go to Step  4.

      NO:  Replace the HUD.

4. STEP 4. Retest the system 

   Operate the angle adjustment switch (+/-) to check whether the brightness of the combiner display area can be adjusted normally.

   Q: Is the check result normal? 

   YES:  The trouble can be an intermittent malfunction (Refer to How to use Troubleshooting/inspection Service Points - HOW TO COPE WITH INTERMITTENT MALFUNCTION ).

   NO:  Replace the HUD.