Inspection Procedure
1: M.U.T.-III cannot Communicate with the Electronically Controller 4WD System.
COMMENTS ON TROUBLE SYMPTOM
If M.U.T.-III cannot communicate with the electronically controlled 4WD system, the CAN
bus lines may have a problem. If the electronically controller 4WD system is not in operation
(in case of no 4WD operation), the 4WD-ECU power supply circuit system or 4WD-ECU may have a
problem.
PROBABLE CAUSES
- Damaged wiring harness and connectors
- 4WD-ECU malfunction
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STEP 1. M.U.T.-III CAN bus diagnostics
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Use M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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Go to Step 2.
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Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting/CAN
Bus Diagnostics Table ). On completion, go to Step 2.
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STEP 2. Voltage measurement at the 4WD-ECU connector
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(1)Disconnect the 4WD-ECU connector.
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(2)Turn the ignition switch to the ON position.
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(3)Measure the voltage between the 4WD-ECU wiring harness side connector terminals
BATT, IG1 (Ignition switch "ON") and the body earth. OK: System voltage
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Q.
Is the check result normal?
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Go to Step 3.
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Repair the connector(s) or terminal(s) or wiring harness.
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STEP 3. Resistance measurement at the 4WD-ECU connector
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(1)Disconnect the 4WD-ECU connector.
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(2)Measure the resistance between the 4WD-ECU wiring harness side connector terminals
No. GND1 and the body earth. OK: Continuity exists (2 Ω or less)
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Q.
Is the check result normal?
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Go to Step 4.
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Repair the connector(s) or terminal(s) or wiring harness.
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STEP 4. Retest the system.
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Q.
Does the malfunction occur again?
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Replace 4WD-ECU (Refer to ). Then go to Step 5
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The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
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STEP 5. Retest the system.
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Q.
Does the malfunction occur again?
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Diagnose again from Step 1.
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This diagnosis is complete.
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