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Inspection Procedure 3: Abnormality in KOS-ECU power supply and ground circuits
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Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
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TECHNICAL DESCRIPTION (COMMENT)
If the KOS-ECU does not work at all or if the KOS-ECU cannot communicate with the scan tool, the KOS-ECU power supply or the ground circuit may be defective.
TROUBLESHOOTING HINTS
- Damaged wiring harness and connectors
- Malfunction of KOS-ECU
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Required Special Tools:
- MB992006: Extra fine probe
- MB991223: Harness set
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STEP 1. Check KOS-ECU connector C-05 and ETACS-ECU connector C-317 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
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Q.
Is the KOS-ECU connector C-05 and ETACS-ECU connector C-317 in good condition?
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 Go to Step 2.
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 Repair the defective connector.
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STEP 2. Check the wiring harness between the KOS-ECU connector C-05 (terminal No.38, 39) and the ETACS-ECU connector C-317 (terminal No.10, 5) for open circuit.
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(1)Disconnect KOS-ECU connector C-05 and ETACS-ECU connector C-317, and check the wiring harness.
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(2)Check the wiring harness between KOS-ECU connector C-05 (terminal No.38) and ETACS-ECU connector C-317 (terminal No.10)
OK: Continuity exists (2 Ω or less)
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(3)Check the wiring harness between KOS-ECU connector C-05 (terminal No.39) and ETACS-ECU connector C-317 (terminal No.5)
OK: Continuity exists (2 Ω or less)
Q.
Is the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ETACS-ECU connector C-317 (terminal No.10, 5) in good condition?
Go to Step 3.
Repair the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ETACS-ECU connector C-317 (terminal No.10, 5).
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STEP 3. Check the wiring harness between the KOS-ECU connector C-05 (terminal No.38, 39) and the ground for short circuit.
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(1)Disconnect KOS-ECU connector C-05, and check the wiring harness.
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(2)Check the wiring harness between KOS-ECU connector C-05 (terminal No.38) and ground
OK: No continuity
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(3)Check the wiring harness between KOS-ECU connector C-05 (terminal No.39) and ground
OK: No continuity
Q.
Is the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ground in good condition?
Go to Step 4.
Repair the wiring harness between KOS-ECU connector C-05 (terminal No.38, 39) and the ground.
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STEP 4. Check the wiring harness between the KOS-ECU connector C-05 and the ground for open circuit.
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(1)Disconnect KOS-ECU connector C-05, and check the wiring harness.
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(2)Check the wiring harness between KOS-ECU connector C-05 (terminal No.14) and ground.
OK: Continuity exists (2 Ω or less)
Q.
Is the wiring harness between KOS-ECU connector C-05 and the ground in good condition?
Go to Step 5.
Repair the wiring harness between KOS-ECU connector C-07 and ground.
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STEP 5. Retest the system
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Q.
Does the abnormality in KOS-ECU power supply and ground circuits in good condition?
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The trouble can be an intermittent malfunction (Refer to GROUP 00, How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction  ).
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Replace KOS-ECU and register the ID codes (Refer to ).
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