Inspection Procedure 2: Communication with the ETACS-ECU is not Possible.






















caution Whenever the ECU is replaced, ensure that the power supply circuit, the earthing circuit and the communication circuit are normal.


COMMENTS ON TROUBLE SYMPTOM


It is suspected that the power supply circuit to the ETACS-ECU is defective, or the wiring harness between the SWS monitor and the ETACS-ECU or their connector(s) is damaged. If the battery power supply circuit to the ECU (terminal No.20 of the ETACS-ECU) is damaged, also check the power supply circuit from the ignition switch (IG1) (terminal No.8 of the ETACS-ECU), and repair if necessary. If the earth circuit to the ECU (terminal No.3 of the ETACS-ECU) is defective, also check the earth circuit to the signal (terminal No.56 of the ETACS-ECU), and repair if necessary.

PROBABLE CAUSES



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

DIAGNOSIS PROCEDURE


STEP 1. Connector check: D-419 and D-420 ETACS-ECU connector


Q. Is the check result normal?

Go to Step 2.
Repair the defective connector.

STEP 2. Voltage measurement at the D-419 ETACS-ECU connector.


(1)Remove the ETACS-ECU, and measure at the junction block side.
(2)Voltage between D-419 ETACS-ECU connector terminal No.20 and body earth
OK: System voltage

Q. Is the check result normal?

Go to Step 4.
Go to Step 3.

STEP 3. Check the wiring harness between D-419 ETACS-ECU connector terminal No.20 and fusible link (1).


note Prior to the wiring harness inspection, check intermediate connector D-241 and junction block connector D-401, and repair if necessary.

  • Check the power supply line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use troubleshooting/Inspection Service Points ).
Repair the wiring harness.

STEP 4. Voltage measurement at the D-419 ETACS-ECU connector.


(1)Remove the ETACS-ECU, and measure at the junction block side.
(2)Turn the ignition switch to the ON position.
(3)Voltage between D-419 ETACS-ECU connector terminal No.8 and body earth
OK: System voltage

Q. Is the check result normal?

Go to Step 6.
Go to Step 5.

STEP 5. Check the wiring harness between D-419 ETACS-ECU connector terminal No.8 and the ignition switch (IG1).


note Prior to the wiring harness inspection, check junction block connector D-403, and repair if necessary.

  • Check the power supply line for open circuit.

Q. Is the check result normal?

Refer to GROUP 54A - Ignition switch, Inspection procedure 2 "Malfunction of the ignition switch power supply system ."
Repair the wiring harness.

STEP 6. Resistance measurement at the D-419 and D-420 ETACS-ECU connector.


(1)Remove the ETACS-ECU, and measure at the junction block side.
(2)Resistance between D-419 ETACS-ECU connector terminal No.3 and body earth
OK: Continuity exists (2 Ω or less)
(3)Resistance between D-420 ETACS-ECU connector terminal No.56 and body earth
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 8.
Go to Step 7.

STEP 7. Check the wiring harness between D-419 ETACS-ECU connector terminal No.3 or D-420 ETACS-ECU connector terminal No.56 and body earth.


note Prior to the wiring harness inspection, check junction block connector D-405, and repair if necessary.

  • Check the earth wires for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use troubleshooting/Inspection Service Points ).
Repair the wiring harness.

STEP 8. Connector check: D-311 column switch connector


Q. Is the check result normal?

Go to Step 9.
Repair the defective connector.

STEP 9. Check the wiring harness from D-420 ETACS-ECU connector terminal No.59 to D-311 column switch connector terminal No.3.



  • Check the communication lines for open and short circuit.

Q. Is the check result normal?

Go to Step 10.
Repair the wiring harness.

STEP 10. ECU check by using the SWS monitor



  • Ignition switch: OFF
ECUS TO BE CHECKED
  • ETACS ECU
OK: "OK" is displayed on the "ETACS ECU" menu.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use troubleshooting/Inspection Service Points ).
Replace the ETACS-ECU.