2020 Mercedes Benz Truck ML 350 4MATIC (164.186) V6-3.5L (272.967) WWW.EBAAUTOPARTS.COM Page 3
General CAN fundamentals
High-Speed CAN (125 kBit/s , 500 kBit/s)
- 125 kBit/s : Interior CAN busSeries 221
- 125 kBit/s : Telematic CAN busSeries 221
- 500 kBit/s : For example:Drive train CAN bus
- 500 kBit/s : For example:Diagnostic CAN-Bus
- This CAN bus does not permit single-wire mode.
- This means that both CAN lines are always required for fault-free communication between the control units.
- This CAN bus requires external terminating resistors.
- The terminating resistors can be located in control units or voltage distributors depending on the CAN bus.
Legend and description for figure 1CAN-H: CAN bus HighCAN-L: CAN bus LowECU 1 ... n: Control unit 1 ... nCAN terminating resistor (
Example: 120ohms)Legend and description for figure 2U 1: Specification approx. 3,6 voltsU 2: Specification approx. 2,5 voltsU 3: Specification
approx. 1,4 voltsContinue with button F2
220.127.116.11. No further information available.
1.1.4. Possible aids and their usage
Evaluation of CAN fault codes
- The control units present in the vehicle (actual configuration) are compared with the coding in control unit CGW (specified configuration).
- Filtering and evaluation of all CAN timeout fault codes present in the vehicleThe result of the evaluation leads to the required test steps.
- Aids for voltage and resistance measurement in menu item 'Measurements with multimeter on CAN network'
- Aid for graphic representation of CAN signal and voltage levels
- The specified characteristics shown in Measurement Technology are used to recognize changed CAN voltage levels, which can be caused by
faulty CAN components.
- Possible procedure: Disconnect and then reconnect the CAN bus subscribers at the voltage distributor one at a time.Compare the pass image
with the actual image from the oscilloscope.
Star Diagnosis CANtool