Absence of Spare bus communication (CAN6 buffer overflow)
• Check connector for the Spare CAN-bus on DAS (pin B7 and B16). • Check wiring for the CAN-bus: - Measure the resistance (with the battery disconnected) between CAN-high (pin B7) and CAN-low (pin B16). It should be close to 60 ohm (one 120 ohm termination resistor in each end of the CAN-bus). - Measure the resistance (with the battery disconnected) between CAN-high on DAS (pin B7) and CAN-high on any other unit on the Spare CAN-bus (e.g. SWM). It should be close to zero Ohm. - Measure the resistance (with the battery disconnected) between CAN-low on DAS (pin B16) and CAN-low on any other unit on the Spare CAN-bus (e.g. SWM). It should be close to zero Ohm. • Check wiring and connector for the ignition signal (pin A1) on the DAS. • Check that no third party controller/instrument is installed. • Check connectors for all ECU:s on the indicated bus. Check for verdigris, broken, unconnected or shorted pins. Disconnect one ecu at a time.
What you'll see
No driver-visible symptom recorded.
System reaction
• Functions dependent on information on the Spare CAN-bus from DAS might be degraded.
Diagnostic depth
The fault is validated as present if the ECU tries to send CAN-messages on the Spare CAN-bus, but no acknowledge is received from other unit(s), and thereby causing the internal buffer in the DAS to overflow. The DTC is set to active if the buffer overflow has lasted for 50 ms. The DTC is set to inactive when the CAN-messages are sent properly again and the buffer no longer is overflowing for the last 1050 ms. The DTC is not validated (stored) if: • the ignition is turned off • first 2 seconds after ignition on • the supply voltage is below 22 volt • the supply voltage is above 32 volt • short circuit on the Spare CAN-bus (separate DTC), except from short circuit between CAN-high and supply voltage
• Defect connectors on DAS for CAN-bus 6 (pin B7 or B16). • Defect wiring for the Spare CAN-bus, open circuit on CAN-high (pin B7) or CAN-low (pin B16). • Ignition signal (pin A1) on DAS is short circuit to supply. • Short circuit between CAN-high and supply voltage. • High busload • Defect ECU unit(s) on the Spare CAN bus. • ECU unit(s) on the CAN-bus communicates with 250 kb/s.