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


If the ETACS-ECU functions do not work at all, the ETACS-ECU power supply system, earth system, or ETACS-ECU may have a problem.

PROBABLE CAUSES




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?

Go to Step 3.

Go to Step 2.

STEP 2. Check of open circuit in EARTH, SGND line between ETACS-ECU 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 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?

Go to Step 5.

Go to Step 4.

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?

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 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?

Go to Step 7.

Go to Step 6.

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?

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 7. Retest the system


Check that the ETACS-ECU functions 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 ).

Replace the ETACS-ECU.