Test N: No Medium Speed Controller Area Network (CAN) Communication

PINPOINT TEST N: NO MEDIUM SPEED CONTROLLER AREA NETWORK (CAN) COMMUNICATION

N1-N3:

N4-N5:

N6-N7:

N8-N10:

N10-N14:

N14-N18:

N19-N21:

Normal Operation
The medium speed CAN has an unshielded twisted pair cable, circuits 2180 (WH/BK) and 2181 (BK/YE). The audio unit or audio navigation unit (if equipped), the driver seat module (DSM) (if equipped), the dual automatic temperature control (DATC) module (if equipped), the digital versatile disc (DVD) player (if equipped), the instrument cluster, and the smart junction box (SJB) are all on the medium speed CAN. The medium speed CAN is not designed to operate under single point fault conditions. If either circuit is shorted to voltage or the medium speed CAN data plus is shorted to ground, module-to-module and module-to-tester communication is not possible. If the medium speed CAN data minus is shorted to ground or an open exists on either bus line, module-to-module and module-to-tester communication is marginal at best. The medium speed CAN may remain operational when one of the two termination resistors are not present. The total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in one of the medium speed CAN circuits, damage to the data link connector (DLC) C251, damage to one of the communications network module connectors, or damage to an in-line connector.

Possible Causes
- medium speed CAN circuits 2180 (WH/BK) and 2181 (BK/YE) open, short to ground, or short to voltage
- DLC C251
- audio unit or audio navigation unit (if equipped)
- DATC module (if equipped)
- DSM (if equipped)
- DVD player (if equipped)
- instrument cluster
- SJB