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Inspection Procedure 3: The position of the combiner display area cannot be adjusted even if the angle adjustment switch is operated.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the brightness of the combiner display area cannot be adjusted even if the brightness adjustment switch is operated, there may be some malfunction in the HUD or in the HUD switch.
 
 
TROUBLESHOOTING HINTS
  • The HUD may be defective
  • The HUD switch [Brightness adjustment switch (+/-): Stuck in OFF] may be defective
  • Damaged harness wires and connectors
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
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
Is the check result normal?
Go to Step 2.
Correct the circuit between the HUD connector and HUD switch connector (BR+, BR- or SW- terminal).
 
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
Is the check result normal?
Go to Step 3.
Replace the HUD switch.
 
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.
(1)
cautionTo 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).
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 nameNormal condition
2Brightness SW(UP)ON
  • When the brightness adjustment switch (+) is not operated.
 
Item No.Item nameNormal condition
2Brightness SW(UP)OFF
  • When the brightness adjustment switch (-) is operated.
 
Item No.Item nameNormal condition
3Brightness SW(DOWN)ON
  • When the brightness switch (-) is not operated.
 
Item No.Item nameNormal condition
3Brightness SW(DOWN)OFF
OK: Normal conditions are displayed for all the items.
Is the check result normal?
Go to Step 4.
Replace the HUD.
 
STEP 4. Retest the system
Operate the angle adjustment switch (+/-) to check whether the brightness of the combiner display area can be adjusted normally.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the HUD.