Malfunction of ETACS-ECU power supply circuit


caution When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in Immobilizer System - How to Register Key ID .)

COMMENTS ON TROUBLE SYMPTOM



PROBABLE CAUSES



  • Damaged harness wires and connectors
  • Malfunction of the ETACS-ECU

DIAGNOSIS PROCEDURE


STEP 1. Resistance measurement at ETACS-ECU connector (EARTH, SGND terminal).


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between the ETACS-ECU connector (EARTH terminal) and body earth.
OK: Continuity exists (2 Ω or less)
(3)Measure the resistance between the ETACS-ECU connector (SGND terminal) and body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?





STEP 2. Check of open circuit in EARTH, SGND line between ETACS-ECU connector and body earth.


Q. Is the check result normal?





STEP 3. Voltage measurement at ETACS-ECU connector (+B terminal).


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Check the voltage between the ETACS-ECU connector (+B terminal) and body earth.
OK: System voltage

Q. Is the check result normal?





STEP 4. Check of short to power supply, short to earth, and open circuit in IODI line between fusible link and ETACS-ECU connector.


Q. Is the check result normal?





STEP 5. Voltage measurement at ETACS-ECU connector (+B1 terminal).


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Check the voltage between the ETACS-ECU connector (+B1 terminal) and body earth.
OK: System voltage

Q. Is the check result normal?





STEP 6. Check of short to power supply, short to earth, and open circuit in +B1 line between fusible link and ETACS-ECU connector.


Q. Is the check result normal?





STEP 7. Retest the system



Q. Is the check result normal?