Inspection Procedure
14: The combination meter and instrument panel illumination does not illuminate normally.
caution
Before replacing the combination
meter, be sure to check that the power supply circuit, earth circuit, and communication circuit
are normal.
COMMENTS ON TROUBLE SYMPTOM
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)
COMMENTS ON TROUBLE SYMPTOM
When the combination meter illumination does not go on or dim normally, the illumination
control circuit, the combination meter or A/C-ECU is defective.
PROBABLE CAUSES
Defective illumination control circuit
Malfunction of combination meter
Malfunction of CAN bus line
Malfunction of heater controller assembly (A/C-ECU)
Damaged harness wires and connectors
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 2
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
STEP 2. M.U.T.-III diagnosis code
Check again if the diagnosis code is set to the combination meter.
Q.
Is the diagnosis code set?
Refer to .
Go to Step 3
STEP 3. M.U.T.-III other system diagnosis code
Check if the A/C-ECU related diagnosis code is set.
Q.
Is the diagnosis code set?
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 the body earth. OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
Go to Step 6
Go to Step 5
STEP 5. Check of short to earth circuit (connect) in GND1 line between
combination meter connector and body earth.
Q.
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 the body earth. OK: System voltage
Q.
Is the check result normal?
Go to Step 9
Go to Step 7
STEP 7. Check of short to power supply circuit (connect) in IL+P
line between the fusible link and combination meter connector.
Q.
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 (connect) in ILL+ or
PWM line between the combination meter connector and meter information switch connector.
Q.
Is the check result normal?
Go to Step 9
Repair the connector(s) or wiring harness.
STEP 9. M.U.T.-III Special Function
Using 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)
Q.
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.
Q.
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 ).