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The rear window defogger does not work.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
The rear window defogger relay may be defective when the rear window defogger cannot be activated although the rear window defogger switch is turned on (the 20-minute timer initiates) or ambient temperature is low (the rear window defogger has never been activated since the ignition switch is turned ON) with "Auto Rear Defogger (Engine Start)" enabled by using the customization function of the ETACS-ECU.
noteWhen the engine is not running, the rear window defogger does not work.
 
 
TROUBLESHOOTING HINTS
  • The rear window defogger relay may be defective
  • The A/C-ECU may be defective
  • The ETACS-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.-IIISE), diagnose the CAN bus line.
(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.
(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.-IIISE), read the DTC.
Check that the A/C controller assembly has not set a DTC.
Is the DTC set?
Carry out the DTC procedures. (Refer to GROUP 55 - Troubleshooting .)
Go to Step 3
 
STEP 3. Using scan tool (M.U.T.-IIISE), read the other system DTC.
Check that the engine control module or ETACS-ECU has not set a DTC.
Is the DTC set?
: Carry out the DTC procedures. (Refer to GROUP 13A - Troubleshooting .)
: Carry out the DTC procedures. Refer to .
Go to Step 4
 
STEP 4. Using scan tool (M.U.T.-IIISE), check data list.
Check the rear window defogger switch signal by the data list of the A/C controller assembly.
  • Start the engine.
  • Turn the rear window defogger switch from off to on.
Item No.Item nameNormal condition
36Rear defogger drive requestOFF → ON
Is the check result normal?
Go to Step 5
Refer to GROUP 55 - Inspection Procedure 8 "A/C controller assembly power supply system" .
 
STEP 5. Voltage measurement at D-108 intermediate connector.
(1) Disconnect the intermediate connector, and measure at its female-side intermediate connector (at the front wiring harness side)
(2) Ignition switch: ON
(3) Rear window defogger switch must be turned on, or the operational conditions for the customization function "Auto Rear Defogger (Engine Start)" must be satisfied (measure within 20 minutes after the switch is turned on).
(4) Check the voltage between the D-108 intermediate connector (terminal No.12) and body ground.
OK: Is the measured voltage approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 6
Go to Step 9
 
STEP 6. Resistance measurement at rear window defogger connectors.
(1) Disconnect the connectors, and measure at the wiring harness side.
(2) Measure the resistance between the rear window defogger connectors and body ground.
  • Measure the resistance between the rear window defogger (liftgate window glass) connector (ground terminal) and body ground.
  • Measure the rear window defogger (liftgate extra window glass) connector (ground terminals) and body ground.
OK: Is the measured resistance 2 ohms or less
Is the check result normal?
Go to Step 8
Go to Step 7
 
STEP 7. Check the wiring harness.
  • Check of open circuit in ground line rear window defogger (liftgate window glass) connector and body ground.
  • Check of open circuit in ground line rear window defogger (liftgate extra window glass) connector and body ground.
Is the check result normal?
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 8. Check the wiring harness.
  • Check of short to power supply, short to ground, and open circuit in power supply line rear window defogger (liftgate window glass) connector and D-108 intermediate connector (terminal No.12).
  • Check of short to power supply, short to ground, and open circuit in power supply line rear window defogger (liftgate extra window glass) connector and D-108 intermediate connector (terminal No.12).
Is the check result normal?
Go to Step 12
Repair the connector(s) or wiring harness.
 
STEP 9. Voltage measurement at ETACS-ECU connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Check the voltage between the ETACS-ECU connector (+B2 terminal) and body ground.
OK: Is the measured voltage approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 11
Go to Step 10
 
STEP 10. Check of short to power supply, short to ground, and open circuit in +B2 line between fusible link and ETACS-ECU connector.
Is the check result normal?
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 11. Check of short to power supply, short to ground, and open circuit in DEFL line between ETACS-ECU connector and D-108 intermediate connector.
Is the check result normal?
Go to Step 12
Repair the connector(s) or wiring harness.
 
STEP 12. Check the rear window defogger.
Check the rear window defogger (Refer to ).
Is the check result normal?
Go to Step 13
Replace the liftgate window glass or liftgate extra window glass.
 
STEP 13. Check the rear window defogger.
Check the rear window defogger (Refer to ).
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.