Principles of Operation
The vehicle uses the following module communication networks
- controller area network (CAN) communications network
- international standards organization (ISO) 9141 communications network
The CAN is comprised of unshielded twisted pair cable, and the ISO 9141 communications network is a single wire network. Both networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one diagnostic tester to be able to diagnose and control any module on the networks from one connector. The DLC can be found under the instrument panel.
Normal Operation
The ABS module communicates with the diagnostic tool through the controller area network (CAN), circuits 4-EC9A (GY) and 5-EC9A (BU). The CAN also connects (through an in-line) to 4-EC7E (GY/RD) and 5-EC7E (BU/RD). Check the CAN circuits between the ABS module C135 (with stability assist) or C155 (ABS only) and the data link connector (DLC) C251. 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 CAN circuits, damage to the DLC C251, damage to the ABS module connector, or a problem in an in-line connector.
The PCM communicates with the diagnostic tool through the controller area network (CAN), circuits 4-EC7 (GY/RD) and 5-EC7 (BU/RD). Check circuits 4-EC7 (GY/RD) and 5-EC7 (BU/RD) between the PCM C175b and the data link connector (DLC) C251. 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 high speed CAN circuits, damage to the DLC C251, damage to the PCM C175b, or a problem in an in-line connector.
The instrument cluster communicates with the diagnostic tool through the controller area network (CAN), circuits 4-EC7B (GY/RD) and 5-EC7B (BU/RD). Check circuits 4-EC7B (GY/RD) and 5-EC7B (BU/RD) between the instrument cluster C2220 and the data link connector (DLC) C251. 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 high speed CAN circuits, damage to the DLC C251, damage to the instrument cluster C2220, or a problem in an in-line connector.
The RCM communicates with the diagnostic tool through the controller area network (CAN), circuits 4-EC18 (GY/BK) and 5-EC18 (BU/BK) as well as circuits 4-EC7E (GY/RD) and 5-EC7E (BU/RD). Check the CAN circuits between the RCM C2041b and the data link connector (DLC) C251. 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 high speed CAN circuits, damage to the DLC C251, damage to the RCM C2041b, or a problem in an in-line connector.
The generic electronic module (GEM) communicates with the diagnostic tool through the ISO 9141 communications network, circuit 8-EE9 (WH/GN). The GEM is the only module on the ISO 9141 communications network. Check circuit 8-EE9 (WH/GN) between the GEM C201d and the data link connector (DLC) C251. The total resistance value must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in the ISO 9141 communications network circuit, damage to the DLC C251, damage to the GEM C201d, or a problem in an in-line connector. If ISO 9141 circuit is not found to be the source of the communication problem, refer to MULTIFUNCTION ELECTRONIC MODULES to diagnose external voltage and ground connections to the GEM.
The CAN has an unshielded twisted pair cable, circuits 4-EC7E (GY/RD) and 5-EC7E (BU/RD). The anti-lock brake system (ABS) module, the instrument cluster, the powertrain control module (PCM), the restraint control module (RCM) and the occupant classification sensor are all on the CAN. The total resistance values from the module to the data link connector (DLC) must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in one of the CAN circuits, damage to the DLC C251, damage to one of the communications network module connectors, or damage to an in-line connector.
Under normal operation the diagnostic tool is connected to the data link connector (DLC) C251 to communicate with the controller area network (CAN), and international standards organization (ISO) 9141 communications networks. If communication cannot be established, the diagnostic tool and the DLC C251 must be checked for damage. If the diagnostic tool and the DLC C251 are OK, circuits 29-RA1 (OG), 91-RA1 (BK/OG) and 31-RA1 (BK) must be checked for an open condition.
See also:
• SUPPLEMENTAL RESTRAINT SYSTEM