Electrical Faults

When there is a fault in the signal levels on the communication wire to the central electronic module (CEM), a diagnostic trouble code (DTC) is stored in the central electronic module (CEM). Each individual communication wire to the central electronic module (CEM), CAN L and CAN H on the low speed side of the network and CAN L and CAN H on the high speed side of the network, is checked. There are two different levels detected on each wire: short-circuit to voltage or short-circuit to earth. As the central electronic module (CEM) can also determine when a short-circuit on one or more wires takes place, the control module can also detect a short-circuit between the two CAN wires in the same part of the network.

This gives eight diagnostic trouble codes for detecting electrical faults.

HINT: The central electronic module (CEM) is unable to store diagnostic trouble codes (DTCs) for open-circuits on the CAN wires. Other diagnostic trouble codes (DTCs) may, however, be stored on account of this.