SERVICE PRECAUTIONS
SERVICE PRECAUTIONS 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 so, a component connected to the CAN bus line may be damaged. - 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 equipment connected through the CAN communication lines, may be damaged. CAUTION: 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, a component 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 twisted wire should be within 10 cm (4.0 inches) 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 twisted wire should be within 10 cm (4.0 inches) from the connector as shown. If it exceeds 10 cm (4.0 inches), twist the wiring harness just like the original twisted wire. If the strand end exceeds 10 cm (4.0 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
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- If the CAN_L or CAN_H line on the main bus line or sub-bus line is repaired, replace 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 strand end of the twisted wire should be within 10 cm (4.0 inches) from the connector. 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), 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 of the terminator resistors is broken, the CAN communication will continue, although noise suppression is deteriorated. In this case, no DTC may be set. Check the system regardless of whether a DTC is set or not. If damage is found, replace the terminator resistor.
FUNCTION
When diagnosing the CAN bus lines, the scan tool MB991958 measures the voltage of CAN_H and CAN_L line and detects the short to power supply or ground.
When diagnosing the CAN bus lines, the scan tool MB991958 measures the voltage of CAN_H and CAN_L line and detects the short to power supply or ground.
If a line-to-line short is present in the CAN bus lines, this diagnosis result will be set.
The resistance in the communication errors condition cannot be measured by the CAN bus diagnostics, therefore, judge the terminator resistor only when receiving the each ECU periodically sent data normally.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the combination meter" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive the combination meter data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the ETACS-ECU" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive the ETACS-ECU data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the A/C-ECU" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive the A/C-ECU data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the SRS-ECU" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive the SRS-ECU data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the TPMS receiver" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive the TPMS receiver data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the ECM < M/T > or PCM < A/T >" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive the ECM < M/T > or PCM < A/T > data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > or TCL/ASC-ECU < vehicles with ASC >" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > or TCL/ASC-ECU < vehicles with ASC > data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from convertible top control module" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive convertible top control module data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the ECM < M/T > or PCM < A/T > and ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > or TCL/ASC-ECU < vehicles with ASC >" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > or TCL/ASC-ECU < vehicles with ASC > and ECM < M/T > or PCM < A/T > data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the ECM < M/T > or PCM < A/T > and ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > or TCL/ASC-ECU < vehicles with ASC >" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > or TCL/ASC-ECU < vehicles with ASC > and ECM < M/T > or PCM < A/T > data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the ECM < M/T > or PCM < A/T > and convertible top control module" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive convertible top control module and ECM < M/T > or powertrain control system < A/T > data only.
The diagnostic result demonstrates that "the scan tool cannot receive the sent data from the ECM < M/T > or PCM < A/T >, ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > and convertible top control module" when the scan tool MB991958 checks the periodically sent data from each ECU and cannot receive convertible top control module, ABS-ECU < vehicles without TCL or ASC > or ABS/TCL-ECU < vehicles with TCL > or TCL/ASC-ECU < vehicles with ASC > and ECM < M/T > or PCM < A/T > data only.