SERVICE PRECAUTIONS
SERVICE PRECAUTIONS CHART Warnings in diagnosis section Details regarding warnings CAUTION: When servicing a CAN bus line, ground yourself by touching a metal object such as an unpainted water pipe. If you fail to do, a component connected to the CAN bus line may be broken. - CAUTION: A digital multimeter should be used. When measuring resistance value or voltage in CAN bus lines, use a digital multimeter. If not using a digital multimeter, the equipments, which are connected through the CAN communication lines, may be damaged. CAUTION: When measuring the resistance, disconnect the negative battery terminal. Disconnect the negative battery terminal when measuring the resistance value in the CAN bus line. If you fail to do so, the equipments, which are connected through the CAN communication lines, may be damaged. CAUTION: The test wiring harness should be used. Always use the test harness when measuring the voltage or resistance value at the female connector. If you fail to do so, connectors may be damaged. CAUTION: The strand end of the twist wire should be within 10 cm from the connector. If you repair the wire due to a defective connector or its terminal or harness wire, you should cut the wire so that the strand end of the twist wire should be within 10 cm (4 inches) from the connector as shown in illustration. If it exceeds 10 cm (4 inches), twist the wiring harness just like the original twisted wire. If the strand end exceeds 10 cm (4 inches), a communication error may be caused. CAUTION: Strictly observe the specified wiring harness repair procedure. When you repair a CAN bus line, observe the precautions on how to repair the CAN bus line strictly. Refer to PRECAUTIONS ON HOW TO REPAIR THE CAN BUS LINES . If a new wire is added or a splice point is modified for the CAN_L or CAN_H line, an error in the CAN communication may be caused
Scheme 734
Scheme 735
Scheme 736
- If the CAN bus line(s) are repaired, renew all the twisted wires between the end connectors. If the wiring harness is partially repaired, or only CAN_L or CAN_H line is repaired, noise suppression is deteriorated, causing a communication error.
- If the connector or wire on the main bus line or the sub-bus wire is replaced, the frayed end of the twisted wire should be within 10 cm (4 inches) from the connector. If it exceeds 10 cm (4 inches), twist the wiring harness just like the original twisted wire. If the frayed end exceeds 10 cm (4 inches), noise suppression is deteriorated, causing a communication error.
- If a sub-bus line is repaired, splice a new wire directly into the main bus line. If a new wire is spliced into the sub-bus line, which is connected to another device, the CAN communication will be disabled.
PRECAUTIONS ON HOW TO REPAIR THE TERMINATOR RESISTOR
If one-side terminator resistor is broken, the CAN communication will continue although noise suppression is deteriorated. No diagnostic trouble code may be set even if the terminator resistor was broken. If damage is found, replace the ECU which incorporates the defective terminator resistor.
FUNCTION
When the CAN bus diagnosis is carried out, the scan tool communicates with the ETACS-ECU. If a communication flag is not set for the ETACS-ECU, the ETACS-ECU will be diagnosed as a communication error.
When the CAN bus diagnosis is carried out, the scan tool sets communication "OK" flags in the patch between the ETACS-ECU and active other ECUs. If a commutation "OK" flag is not set for the ECUs other than the ETACS-ECU, this diagnosis result will be set.
If a line-to-line short is present in the CAN-C lines, this diagnosis result will be set.
If a short to ground is present in the CAN-C lines, this diagnosis result will be set.
If a short to power supply is present in the CAN-C lines, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the AWC-ECU, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the steering wheel sensor, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the shift lever, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the ASC-ECU, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the ECM, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the TC-SST-ECU, this diagnosis result will be set.
If a failure is present in the wiring harness between the ETACS-ECU connector and the joint connector (CAN2), this diagnosis result will be set.
If a failure is present in the wiring harness between the joint connector (CAN2) and the joint connector (CAN3), this diagnosis result will be set.
If a failure is present in the wiring harness between the joint connector (CAN3) and the joint connector (CAN4), this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the KOS-ECU, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the WCM, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the SRS-ECU, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the occupant classification-ECU, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the A/C-ECU or heater control unit , this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the radio and CD player or CD changer, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the CAN box unit, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the satellite radio tuner, this diagnosis result will be set.
If the scan tool MB991958 cannot communicate with the combination meter, this diagnosis result will be set.
If a short to power supply or ground is present in both CAN_H and CAN_L lines, this diagnosis result will be set.
If a failure is present in the wiring harness wires between the ETACS-ECU connector, the joint connector (CAN1), the ETACS-ECU connector and the joint connector (CAN1), this diagnosis result will be set.
If a short to power supply or ground, open circuit or line-to-line short is present at either CAN_H or CAN_L side on the CAN-B lines, this diagnosis result will be set.