Absence of Yellow bus communication (CAN2 buffer overflow)
• Check connector for yellow CAN-bus on COO (pin B2 and B11). • Check wiring for yellow CAN-bus: - Measure the resistance (with the battery disconnected) between CAN-high on COO (pin B2) and CAN-high on any other unit on the yellow CAN-bus (e.g. CUV). It should be close to zero Ohm. - Measure the resistance (with the battery disconnected) between CAN-low on COO (pin B11) and CAN-low on any other unit on the yellow CAN-bus (e.g. CUV). It should be close to zero Ohm. • Check wiring and connector for the ignition signal (pin A1) on the COO. • 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
• Warnings for COO malfunction will be active in the instrument cluster. • Functions dependent on information on yellow CAN-bus from COO might be degraded. Examples listed below. - brake lights (will be active continuously) - fuel level gauge in instrument cluster
Diagnostic depth
Communication error. Yellow CAN-bus buffer overflow. The Yellow CAN-bus has an open circuit or a short circuit.
• Defect connectors on COO for yellow CAN- bus (pin B2 or B11). • Defect wiring for red CAN-bus, open circuit on CAN-high (pin B2) or CAN-low (pin B11). • Ignition signal (pin A1) on COO is short circuit to supply. • Short circuit between CAN-high and supply voltage. • High busload • Defect ECU unit(s) on the yellow CAN-bus.