Wednesday, May 29, 2019

2010 Mercedes Benz C 300 (204.054) V6-3.0L (272.947) Page 1589


- A CAN timeout fault code is set due to the absence of a CAN input signal.The cause of this may be not only the transmitter control unit, but



also the CAN networking.



- For example:No CAN message was received from control unit A.



Bus OFF fault



- A Bus OFF fault code is set, when the control unit cannot send a certain amount of messages to the CAN bus or the messages are



incomplete.The control unit then switches off for a short time from CAN bus.



- For example:CAN controller: CAN bus OFF



Functional CAN fault



- A functional CAN fault code is set because of an implausible CAN input signal.The cause of this is not the CAN networking, but the



transmitter control unit or its sensors.



- For example:CAN signal 'A' from control unit B is implausible.



Notes on CAN faults that cannot be read out as fault codes.Bus wake-up event



- An event that wakes up the bus without reason is designated a bus wake-up event.



- The cause of this is not the CAN networking, but the transmitter control unit or its sensors.



- Further possible causes of fault:



- Magnetic fields caused by nearby high-voltage installations, railroad installations or power plants.



- Magnetic fields can radiate on to lines and control units in rare cases and cause undefined behavior in the control units.



- The special tool 'Star Diagnosis CANtool' can be used to log bus wake-up events, bus keepawake events and other signals.



Bus keepawake event



- When a control unit keeps communication on the bus awake without reason, this is designated a bus keepawake event.



- The cause of this is not the CAN networking, but the transmitter control unit or its sensors.



- Further possible causes of fault:



- Magnetic fields caused by nearby high-voltage installations, railroad installations or power plants.



- Magnetic fields can radiate on to lines and control units in rare cases and cause undefined behavior in the control units.



- The special tool 'Star Diagnosis CANtool' can be used to log bus wake-up events, bus keepawake events and other signals.



2.1.1.2. No further information available.



2.1.1.3. General CAN fundamentals



Test 2.1.1.3.1: High-Speed CAN (125 kBit/s , 500 kBit/s)



Test 2.1.1.3.2: Low-Speed CAN (83,3 kBit/s)



2.1.1.3.1. High-Speed CAN (125 kBit/s , 500 kBit/s)



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

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