[54E] SMART WIRING SYSTEM (SWS) USING SWS MONITOR <Except for Hong Kong spec.> - - SYMPTOM PROCEDURES - INSPECTION PROCEDURE A-4: Communication with the front-ECU is not possible. | PRINT PAGE / INDEX / PRIOR / NEXT

INSPECTION PROCEDURE A-4: Communication with the front-ECU is not possible.
| CAUTION Whenever the ECU is replaced, ensure that the power supply circuit, the grounding circuit and the communication circuit are normal.
| COMMENTS ON TROUBLE SYMPTOM It is suspected that the power supply circuit to the front-ECU is defective, or the wiring harness between the SWS monitor and the front-ECU or their connector(s) is damaged. If the battery power supply circuit to the ECU (terminal No.5 of the front-ECU) is damaged, also check the power supply circuit from the ignition switch (IG2) (terminal No.22 of the front-ECU), and repair if necessary.
| POSSIBLE CAUSES Malfunction of the front-ECU Malfunction of the ETACS-ECU Damaged harness wires and connectors
| DIAGNOSIS PROCEDURE
| Step 1. ECU check by using the SWS monitor Check that the power supply and earth lines to the ETACS-ECU and the SWS communication lines are normal. Ignition switch: OFF ECU TO BE CHECKED ETACS ECU OK: "OK" is displayed on the "ETACS ECU" menu. Q: Is the check result normal? YES: Go to Step 2. NO: Refer to Inspection Procedure A-3 "Communication with ETACS-ECU is not possible ."
| Step 2. Connector check: A-11X front-ECU connector Q: Is the check result normal? YES: Go to Step 3. NO: Repair the defective connector.
| Step 3. Measure the voltage at A-11X front-ECU connector. Disconnect the connector, and measure at the relay box side. Ignition switch: ON Voltage between A-11X front-ECU connector No.5 and body earth OK: Battery positive voltage Q: Is the check result normal? YES: Go to Step 6. NO <LH drive vehicle>: Go to Step 4. NO <RH drive vehicle>: Go to Step 5.
| Step 4. Check the wiring harness between A-11X front-ECU connector terminal No.5 and the battery. Check the power supply line for open circuit. Q: Is the check result normal? YES: The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ). NO: Repair the wiring harness.
| Step 5. Check the wiring harness between A-11X front-ECU connector terminal No.5 and fusible link (1). NOTE: Prior to the wiring harness inspection, check junction block connectors C-202, C-204, intermediate connectors A-14, C-116, C-125 and repair if necessary. Check the power supply line for open circuit. Q: Is the check result normal? YES: The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ). NO: Repair the wiring harness.
| Step 6. Connector check: A-12X front-ECU connector Q: Is the check result normal? YES: Go to Step 7. NO: Repair the defective connector.
| Step 7. Measure the resistance at A-11X front-ECU connector. Disconnect the connector, and measure at the relay box side. Resistance between A-12X front-ECU connector terminal No.21 and body earth OK: 2 Ω or less Q: Is the check result normal? YES: Go to Step 9. NO: Go to Step 8.
| Step 8. Check the wiring harness between A-12X front-ECU terminal connector No.21 and body earth. Check the earth wires for open circuit. Q: Is the check result normal? YES: The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ). NO: Repair the wiring harness.
| Step 9. Connector check: C-219 ETACS-ECU connector Q: Is the check result normal? YES: Go to Step 10. NO: Repair the defective connector.
| Step 10. Check the wiring harness between A-12X front-ECU connector terminal No.30 and C-219 ETACS-ECU connector terminal No.59. NOTE: Prior to the wiring harness inspection, check joint connector C-02 and intermediate connector C-116, and repair if necessary. Check the communication lines for open circuit. Q: Is the check result normal? YES: Go to Step 11. NO: Repair the wiring harness.
| Step 11. ECU check by using the SWS monitor Check that the power supply and earth lines to the front-ECU and the SWS communication lines are normal. Ignition switch: ON ECU TO BE CHECKED FRONT ECU OK: "OK" is displayed on the "FRONT ECU" menu. Q: Is the check result normal? YES: The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ). NO: Replace the front-ECU.

[54E] SMART WIRING SYSTEM (SWS) USING SWS MONITOR <Except for Hong Kong spec.> - - SYMPTOM PROCEDURES - INSPECTION PROCEDURE A-4: Communication with the front-ECU is not possible. | PRINT PAGE / INDEX / PRIOR / NEXT

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