12/4/19

2020 Mercedes Benz Truck ML 350 4MATIC (164.186) V6-3.5L (272.967) WWW.EBAAUTOPARTS.COM Page 3

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



1.1.3.2. 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.



Multimeter



- Aids for voltage and resistance measurement in menu item 'Measurements with multimeter on CAN network'



Measuring system



- 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

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