Absence of SubCAN bus CAN communication (CAN2 buffer overflow)
• Check connector for SubCAN bus on ACS (pin A9 and A12). • Check wiring for SubCAN bus: - Measure the resistance (with the battery disconnected) between CAN-high (pin C11) and CAN-low (pin C12). 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 ACS (pin C11) and CAN-high on the ACSX unit. It should be close to zero Ohm. - Measure the resistance (with the battery disconnected) between CAN-low on ACS (pin C12) and CAN-low on the ACSX unit. It should be close to zero Ohm. • Check wiring and connector for the ignition signal (pin A11) on the ACS.
What you'll see
No driver-visible symptom recorded.
System reaction
Amber ACS warning lamp Speed Limitation
Diagnostic depth
SubCAN bus buffer overflow, which indicates a communication error. The SubCAN bus has an open circuit.
• Defect connectors on ACS, related to the SubCAN bus (pin C11 or C12). • Defect wiring for SubCAN bus, open circuit on CAN high (pin C11) or CAN low (pin C12). • Ignition signal (pin A11) on ACS is short circuit to supply (only ACS is awake on the SubCAN bus). • Short circuit between CAN high and supply voltage. • High busload • Defect ECU unit(s) on the SubCAN bus.