Inspection Procedure A-3
Communication with the ETACS-ECU is ImpossibleETACS-ECU Power Supply And SWS Communication Circuit:
Connectors:
CIRCUIT OPERATION
- The power supply to the ETACS-ECU is provided by the battery and the ignition switch (IG1).
- If the power supply system from the battery is defective, the system operates by the power supply from the ignition switch (IG1).
TECHNICAL DESCRIPTION (COMMENT)
It is suspected that the power supply circuit to the ETACS-ECU is defective, or the wiring harness between the SWS monitor kit 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 ground circuit to the ECU (terminal No. 3 of the ETACS-ECU) is damaged, also check the ground circuit to the sensor (terminal No. 56 of the ETACS-ECU), and repair if necessary.
TROUBLESHOOTING HINTS
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors
DIAGNOSIS
Required Special Tools:
- MB991223: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991862: SWS monitor kit
STEP 1. Measure at ETACS-ECU connector C-226 in order to check the battery power supply circuit to the ETACS- ECU.
1. Disconnect ETACS-ECU connector C-226, and measure at the junction block side.
2. Measure the voltage between terminal 20 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES: Go to Step 4.
NO: Go to Step 2.
STEP 2. Check ETACS-ECU connector C-226 for damage.
Q: Is ETACS-ECU connector C-226 in good condition?
YES: Go to Step 3.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The system should communicate with the ETACS-ECU normally.
STEP 3. Check the wiring harness between ETACS-ECU connector C-226 and the battery.
NOTE: Also check intermediate connector C-129, junction block connector C-210 and joint connector C-05. If intermediate connector C-129, junction block connector C-210 or joint connectors C-05 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between ETACS-ECU connector C-226 and the battery in good condition?
YES: No action to be taken.
NO: Repair the wiring harness. The system should communicate with the ETACS-ECU normally.
STEP 4. Measure at ETACS-ECU connector C-226 in order to check the ground circuit to the ETACS-ECU.
1. Disconnect ETACS-ECU connector C-226, and measure at the junction block side.
2. Measure the resistance value between terminal 3 and ground.
- The measured value should be 2 Ohm or less.
Q: Does the measured resistance value correspond with this range?
YES: Go to Step 7.
NO: Go to Step 5.
STEP 5. Check ETACS-ECU connector C-226 for damage.
Q: Is ETACS-ECU connector C-226 in good condition?
YES: Go to Step 6.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The system should communicate with the ETACS-ECU normally.
STEP 6. Check the wiring harness between ETACS-ECU connector C-226 and the ground.
NOTE: Also check joint connector C-06 and junction block connector C-214. If joint connector C-06 or junction block connector C-214 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between ETACS-ECU connector C-226 and the ground in good condition?
YES: No action to be taken.
NO: Repair the wiring harness. The system should communicate with the ETACS-ECU normally.
STEP 7. Check column switch connector C-206 and ETACS-ECU connector C-228 for damage.
Q: Are column switch connector C-206 and ETACS-ECU connector C-228 in good condition?
YES: Go to Step 8.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The system should communicate with the ETACS-ECU normally.
STEP 8. Check the wiring harness between column switch connector C-206 and ETACS-ECU connector C-228.
Q: Is the wiring harness between column switch connector C-206 and ETACS-ECU connector C-228 in good condition?
YES: Replace the ETACS-ECU. The system should communicate with the ETACS-ECU normally.
NO: Repair the wiring harness. The system should communicate with the ETACS-ECU normally.