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Inspection Procedure 14: The combination meter and instrument panel illumination does not illuminate normally.
 
 
cautionBefore replacing the combination meter, be sure to check that the power supply circuit, ground circuit, and communication circuit are normal.
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
The combination meter illumination will go on when the ignition switch is turned ON, and dim by operating the meter information switch <Standard meter> or rheostat illumination switch <High contrast meter>. When the combination meter illumination does not go on or dim normally, the following conditions may be present.
The combination meter is dimmed by operating the switch.
  • Defective illumination control circuit
  • Malfunction of combination meter
After the A/C-ECU received signal from the combination meter, it has dimmed all the switch indicators.
  • Malfunction of CAN bus line
  • Malfunction of heater controller assembly (A/C-ECU)
 
 
TROUBLESHOOTING HINTS
  • Defective illumination control circuit
  • The combination meter may be defective.
  • The CAN bus line may be defective.
  • The heater controller assembly (A/C-ECU) may be defective.
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus line
(1)
cautionTo 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 (M.U.T.-III). Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the CAN bus line found to be normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
 
STEP 2. Using scan tool (M.U.T.-III), read the combination meter diagnostic trouble code
Check again if the DTC is stored in the combination meter.
Is the DTC stored?
Refer to .
Go to Step 3
 
STEP 3. Using scan tool (M.U.T.-III), read for A/C-ECU diagnostic trouble code.
Check if DTC is stored in the A/C-ECU.
Is the DTC stored?
Troubleshoot the A/C or heater (GROUP 55, Auto A/C Diagnosis ).
Go to Step 4
 
STEP 4. Resistance measurement at the combination meter connector
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the combination meter connector (GND1 terminal) and ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 6
Go to Step 5
 
STEP 5. Check of short to ground circuit in GND1 line between combination meter connector and ground.
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 ).
Repair the connector(s) or wiring harness.
 
STEP 6. Voltage measurement at the combination meter connector
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the voltage between the combination meter connector (IL+P terminal) and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 9
Go to Step 7
 
STEP 7. Check of short to power supply circuit in IL+P line between the fusible link and combination meter connector.
Is the check result normal?
Go to Step 8
Repair the connector(s) or wiring harness.
 
STEP 8. Check of short to power supply circuit in ILL+ or PWM line between the combination meter connector and meter information switch connector.
Is the check result normal?
Go to Step 9
Repair the connector(s) or wiring harness.
 
STEP 9. Check by scan tool (M.U.T.-III) "Special Function"
Using scan tool (M.U.T.-III), select "Test" from the special function of the combination meter. Execute the following item to check the liquid crystal display.
  • Item 5: Illumination (AUTO)
Is the check result normal?
Go to Step 10
Replace the combination meter.
 
STEP 10. Retest the system.
Check that combination meter illumination function should work 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 combination meter.