Principles of Operation
The vehicle has 3 module communication networks: high speed and medium speed CAN network, which are comprised of unshielded twisted pair cable, and the international standards organization (ISO) 9141 communication network, which is a single wire network. All 3 networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing a diagnostic tester to be able to diagnose and control any module on the 3 networks from the connector. The DLC can be found under the instrument panel between the steering column and the radio.
The high speed and medium speed CAN remain operational even with the severing of one of the bus wires. Communications will also continue if one of the bus wires is shorted to ground or voltage. If any of the termination resistors are lost, communication is not possible.
The ISO 9141 communication network does not permit intermodule communication. When the diagnostic tool communicates to modules on the ISO 9141 communication network, the diagnostic tool must ask for all information; the modules cannot initiate communications.
The ISO 9141 communication network will not function if the wire is shorted to ground or battery voltage. Also, if one of the modules on the ISO 9141 communication network loses power or shorts internally, communication to that module will fail.
Normal Operation
The PCM communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes shorted to ground or voltage, communications can continue at a reduced level. The PCM and instrument cluster share network termination responsibilities with the use of a split termination resistor in each module. If either of these termination resistors is lost, network communication is not possible. Check circuits 1908 (WH) and 1909 (BK) between the PCM C175b and the data link connector (DLC) C251. 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 RCM communicates with the diagnostic tool through the ISO 9141 communication network circuit 70 (LB/WH). If circuit 70 (LB/WH) becomes open or shorted to ground, communication to that module is not possible. Check circuit 70 (LB/WH) between the RCM C2041a and the data link connector (DLC) C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in the ISO 9141 communication network circuit, damage to the DLC C251, or damage to the RCM C2041a.
The ABS module communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes shorted to ground or voltage, communication can continue at a reduced level. Check circuits 1908 (WH) and 1909 (BK) between the ABS module C155 and the data link connector (DLC) C251. 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 ABS module C155, or a problem in an in-line connector.
The 4WD control module communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes shorted to ground or voltage, communication can continue at a reduced level. Check circuits 1908 (WH) and 1909 (BK) between the 4WD control module C3253 and the data link connector (DLC) C251. 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 4WD control module C3253, or a problem in an in-line connector.
The parking aid module communicates with the diagnostic tool through the ISO 9141 communication network circuit 70 (LB/WH). If circuit 70 (LB/WH) becomes open or shorted to ground, communication to that module is not possible. Check circuit 70 (LB/WH) between the parking aid module C4014 and the data link connector (DLC) C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is an open in circuit 70 (LB/WH), damage to the DLC C251, damage to the parking aid module C4014, or a problem in an in-line connector.
The parking aid module and the restraint control module (RCM) communicate with the diagnostic tool through the ISO 9141 communication network circuit 70 (LB/WH). If circuit 70 (LB/WH) becomes open or shorted to ground, communication to those modules is not possible. Check circuit 70 (LB/WH) between the parking aid module C4014, RCM C2041a and the data link connector (DLC) C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is an open in circuit 70 (LB/WH), damage to the DLC C251, damage to the parking aid module, the RCM, or a problem in one of the in-line connectors. If, after individual checks of each circuit leading to a module show resistance values less than 5 ohms and no in-line connector issues present, the data link diagnostics test must be run with the module in question disconnected. If the data link diagnostics test passes with the module in question disconnected, the module is the source of the concern. A new module should be installed.
The medium speed CAN has an unshielded twisted pair cable, circuits 1847 (WH/OG) and 1848 (PK/OG). The smart junction box (SJB) and the instrument cluster are the only modules on the medium speed CAN. Total network 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 network module connectors, or damage to an in-line connector. Since both the SJB and the instrument cluster share network termination responsibilities, a problem in either of these modules can result in a medium speed CAN failure.
The high speed CAN has an unshielded twisted pair cable, circuits 1908 (WH) and 1909 (BK). The powertrain control module (PCM), anti-lock brake system (ABS) module, four-wheel drive (4WD) control module, and the instrument cluster are all on the high speed CAN. Total network 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 data link connector (DLC) C251, damage to one of the network module connectors, or damage to an in-line connector. Since both the PCM and the instrument cluster share network termination responsibilities, a problem in either of these modules can result in a high speed CAN failure.
The diagnostic tool is connected to the DLC C251 to communicate with both the high speed and medium speed controller area network (CAN), as well as with the international standards organization (ISO) 9141 communication network. 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 956 (OG/LG), 570 (BK/WH), and 57 (BK) must be checked for an open condition.
The vehicle has 4 module communication networks: the first 2 are the high speed and medium speed CAN networks, which are comprised of an unshielded twisted pair cable. The third network is the international standards organization (ISO) 9141 communication network, which is a single wire network. The fourth network is the audio control protocol (ACP) network, which consists of a twisted pair cable and a control line. The first 3 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 3 networks from one connector. The DLC can be found under the instrument panel between the steering column and the audio unit.
The high speed and medium speed CAN networks can remain operational at a reduced level even with an open in the system. If one of the bus wires becomes shorted to ground or shorted to voltage, communication over the network may not be possible.
The ISO 9141 communication network does not permit intermodule communication. When the diagnostic tool communicates to modules on the ISO 9141 communication network, the diagnostic tool must ask for all information; the modules cannot initiate communications.
The ISO 9141 communication network does not function if the wire is shorted to ground or battery voltage. Also, if one of the modules on the ISO 9141 communication network loses power or shorts internally, communications to that module may fail.
The power steering control module communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes open, communication with the power steering control module will cease. The rest of the CAN network may continue to communicate at a reduced level, based on the location of the open circuit. Check circuits 1908 (WH) and 1909 (BK) between the power steering control module C 1463a and the data link connector (DLC) C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is either an open in one of the high speed CAN circuits, damage to the DLC C251, damage to the power steering control module C1463a, or a problem in an in-line connector.
The TCM communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes open, communication with the TCM will cease. The rest of the CAN network may continue to communicate at a reduced level, based on the location of the open circuit. Check circuits 1908 (WH) and 1909 (BK) between the TCM C1458a and the data link connector (DLC) C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is either an open in one of the high speed CAN circuits, damage to the DLC C251, damage to the TCM C145 8 a, or a problem in an in-line connector.
The ABS module communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes shorted to ground or voltage, communication can continue at a reduced level. Check circuits 1908 (WH) and 1909 (BK) between the ABS module C1462 and the data link connector (DLC) C251. 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 ABS module C1462, or a problem in an in-line connector.
The instrument cluster communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes shorted to ground or voltage, communications can continue at a reduced level. Check circuits 1908 (WH) and 1909 (BK) between the instrument cluster C220 and the data link connector (DLC) C251. Also check circuits 1847 (WH/OG) and 1848 (PK/OG) between the instrument cluster C220 and the data link connector (DLC) C251. 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 C220, or a problem in an in-line connector.
The PCM communicates with the diagnostic tool through the high speed CAN communications network, circuits 1908 (WH) and 1909 (BK). If one of the bus wires becomes shorted to ground or voltage, communications can continue at a reduced level. The PCM and traction battery control module (TBCM) share network termination responsibilities with the use of a split termination resistor in each module. If either of these termination resistors is lost, network communication is not possible. Check circuits 1908 (WH) and 1909 (BK) between the PCM C175b and the data link connector (DLC) C251. 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 medium speed CAN has an unshielded twisted pair cable, circuits 1847 (WH/OG) and 1848 (PK/OG). The smart junction box (SJB), the instrument cluster and the audio control protocol (ACP) are the only modules on the medium speed CAN. Total network resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is either an open in one of the medium speed CAN circuits, damage to the data link connector (DLC) C251, damage to one of the network module connectors, or damage to an in-line connector. Since both the SJB and the instrument cluster share network termination responsibilities, a problem in either of these modules can result in a medium speed CAN failure. The ACP module is not able to communicate with the diagnostic tool.
The high speed CAN has an unshielded twisted pair cable, circuits 1908 (WH) and 1909 (BK). The powertrain control module (PCM), anti-lock brake system (ABS) module, four-wheel drive (4WD) control module, instrument cluster, power steering control module, transaxle control module (TCM) and the traction battery control module (TBCM) are all on the high speed CAN. Total network resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms, there is either an open in one of the high speed CAN circuits, damage to the data link connector (DLC) C251, damage to one of the network module connectors, or damage to an in-line connector. Since both the PCM and the TBCM share network termination responsibilities, a problem in either of these modules can result in a high speed CAN failure.