Principles of Operation
The vehicle has 3 module communication networks
- controller area network (CAN)
- universal asynchronous receiver transmitter (UART) based protocol (UBP)
- international standards organization (ISO) 9141
The CAN has an unshielded twisted pair cable, data bus plus, circuit 1827 (WH/LG) and data bus minus, circuit 1828 (PK/LG). The UBP communications network uses a single wire network circuit 1906 (VT), as does the ISO 9141 communications network, which is a single wire network, circuit 70 (LB/WH). All three networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one diagnostic tool to be able to diagnose and control any module on the three networks from one connector. The DLC can be found under the instrument panel between the steering column and the radio.
The ISO 9141 communications network does not permit inter-module 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 communications network will not function if the wire is shorted to ground or battery voltage. Also, if one of the modules on the ISO 9141 communications network loses power or shorts internally, communications to that module will fail.
The UBP communications network will not function if the wire is shorted to ground or voltage. The UBP communication network allows intermodule communication. If one of the modules on the UBP communications network loses power or shorts internally, communications to that module will fail.
The CAN permits inter-module communication between the DLC, PCM, instrument cluster and the ABS module. When the diagnostic tool communicates to modules on the CAN, the diagnostic tool must request all information or initiate module commands.
The CAN will not function if the wire is shorted to ground or battery voltage. Also, if one of the modules on the CAN loses power or shorts internally, communications to that module will fail. Both the PCM and the instrument cluster have internal termination resistors required for correct network communications operation.
The PCM communicates with the diagnostic tool through the CAN circuits 1827 (WH/LG) and 1828 (PK/LG). If one of the bus wires becomes shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. Check circuits 1827 (WH/LG) and 1828 (PK/LG) between the PCM C175b and the DLC C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open circuit in the CAN, damage to the DLC C251, damage to the PCM C175b, or a problem in the in-line connector.
Vehicle Identification (VID) Block
Some PCMs contain a memory area called a vehicle identification (VID) block. The PCM VID block may contain the factory settings for the configurable modules unless the PCM is flashed with a new calibration, in which case some PCM parameters may be modified.
As-Built Data Center
The As-Built Data Center maintains a record of the vehicle configuration in a database. The vehicle VIN is required to obtain this information. The As -Built Data Center records the applicable module configurations stored in each module before the vehicle leaves the factory. The As-Built Data Center will always reflect the original build of the vehicle as it left the factory. Contact the As-Built Data Center only when directed to do so by the WDS.
The vehicle security module controls the remote keyless entry (RKE) system and power lock system. Refer to HANDLES, LOCKS, LATCHES AND ENTRY SYSTEMS .
The driver seat module (DSM) allows automatic positioning of the memory driver seat and the memory pedals to three programmable positions. Refer to SEATING .
Normal Operation
The vehicle security module controls the remote keyless entry (RKE) and power door locks. The vehicle security module receives power through the central junction box (CJB) fuse 107 (30A) and fuse 18 (10A). From these fuses power is delivered to the module through circuits 294 (WH/LB) and 7 (LG/YE), and is grounded on circuits 938 (BK/LG) and 57 (BK). The vehicle security module communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 1906 (VT). If circuit 1906 (VT) becomes open or shorted to ground communications to that module will not be possible. Check circuit 1906 (VT) between the vehicle security module C3008b and the 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 1906 (VT), damage to the DLC C251, damage to the vehicle security module C3008b, or a problem in the in-line connector.
The PCM communicates with the diagnostic tool through CAN circuits 1827 (WH/LG) and 1828 (PK/LG). If one of the bus wires becomes shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. Check circuits 1827 (WH/LG) and 1828 (PK/LG) between the PCM C175b and the 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 1827 (WH/LG) and 1828 (PK/LG), damage to the DLC C251, damage to the PCM C175b, or a problem with the in-line connector.
The RCM communicates with the diagnostic tool through the ISO 9141 communications network circuit 70 (LB/WH). If circuit 70 (LB/WH) becomes open or shorted to ground communications to that module will not be possible. Check circuit 70 (LB/WH) between the RCM C310a and the 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, or damage to the C310a.
The DSM receives power through the central junction box (CJB) fuse 109 (30A) and fuse 3 (5A). From the fuses power is delivered to the module through circuits 566 (DG) and 956 (OG/LG), and is grounded on circuits 875 (BK/LB) and 57 (BK).
The DSM communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 1906 (VT). If circuit 1906 (VT) becomes open or shorted to ground communications to that module will not be possible. Check circuit 1906 (VT) between the DSM C341c and the 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 1906 (VT), damage to the DLC C251, damage to the DSM C341c, or a problem in the in-line connector.
The parking aid module communicates with the diagnostic tool through the ISO 9141 communications network circuit 70 (LB/WH). If circuit 70 (LB/WH) becomes open or shorted to ground communications to that module will not be possible. Check circuit 70 (LB/WH) between the parking aid module C2023 and the 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 C2023, or a problem in the in-line connectors.
The instrument cluster communicates with the diagnostic tool through the CAN communications network circuits 1827 (WH/LG) and 1828 (PK/LG). If one of the bus wires becomes shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. Check circuits 1827 (WH/LG) and 1828 (PK/LG) between the instrument cluster C220a and the 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 1827 (WH/LG) and 1828 (PK/LG), damage to the DLC C251, damage to the instrument cluster C220a, or a problem with the inline connector.
The EATC module communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 1906 (VT). If circuit 1906 (VT) becomes open or shorted to ground communications to that module will not be possible. Check circuit 1906 (VT) between the EATC C294c and the 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 1906 (VT), damage to the DLC C251, damage to the EATC C294c, or a problem in the in-line connector.
The ABS module communicates with the diagnostic tool through the CAN communications network circuits 1827 (WH/LG) and 1828 (PK/LG). If one of the bus wires becomes shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. Check circuits 1827 (WH/LG) and 1828 (PK/LG) between the ABS module C135 and the 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 1827 (WH/LG) and 1828 (PK/LG), damage to the DLC C251, damage to the ABS module C135, or a problem with the in-line connector.
The PCM, ABS module and the instrument cluster communicate with the diagnostic tool through CAN circuits 1827 (WH/LG) and 1828 (PK/LG). If one of the bus wires become shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. If a module is lost due to internal concerns, communications can continue to all other modules. Check circuits 1827 (WH/LG) and 1828 (PK/LG) between the PCM C175b, ABS module C135, instrument cluster C220a, and the 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 circuits 1827 (WH/LG) and 1828 (PK/LG), damage to the DLC C251, damage to the PCM C175b, ABS module C135, instrument cluster C220a, a problem in the in-line connectors or an internal problem with the PCM, ABS module, or the instrument cluster. 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 links diagnostics test passes with the module in question disconnected, it is the source of the concern and should be removed and a new module installed.
The reverse parking aid module and the restraint control module (RCM) communicate with the diagnostic tool through the ISO 9141 communications network circuit 70 (LB/WH). If circuit 70 (LB/WH) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 70 (LB/WH) between the parking aid module, RCM and the 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, 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 links diagnostics test passes with the module in question disconnected it is the source of the concern and should be removed and a new module installed.
The DSM, vehicle security module, EATC module and the instrument cluster all communicate with the diagnostic tool through the UBP communications network circuit 1906 (VT). If circuit 1906 (VT) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 1906 (VT) between the DSM, vehicle security module, EATC, instrument cluster and the 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 1906 (VT), damage to the DLC C251, damage to the DSM, vehicle security module, EATC, instrument cluster, 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 links diagnostics test passes with the module in question disconnected, it is the source of the concern and should be removed and a new module installed.
The diagnostic tool is connected to the DLC C251 to communicate with the controller area network (CAN), universal asynchronous receiver transmitter (UART)-based protocol (UBP), and the international standards organization (ISO) 9141 communications networks. If communication can not 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 40 (LB/WH), 57 (BK) and 567 (LB/YE) must be checked for an open condition.