Absence of FMS bus CAN communication (CAN4 buffer overflow)
• Check connector for FMS CAN-bus on BCI (pin C20 and C17). • Check wiring for FMS CAN-bus: - Measure the resistance (with the battery disconnected) between CAN-high (pin C20) and CAN-low (pin C17). 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 BCI (pin C20) and CAN-high on any other unit on the FMS CAN-bus. It should be close to zero ohm. - Measure the resistance (with the battery disconnected) between CAN-low on BCI (pin C17) and CAN-low on any other unit on the FMS CAN-bus. It should be close to zero ohm. • Check wiring and connector for the ignition signal (pin A11) on the BCI.
What you'll see
No driver-visible symptom recorded.
System reaction
• Functions dependent on information on the FMS CAN-bus from BCI might be degraded.
Diagnostic depth
Communication error. FMS CAN-bus buffer overflow. The FMS CAN-bus has an open circuit.
• Defect connectors on BCI for FMS CAN-bus (pin C20 or C17). • Defect wiring for FMS CAN-bus, open circuit on CAN-high (pin C20) or CAN-low (pin C17). • Ignition signal (pin A11) on BCI is short circuit to supply.