Principles of Operation
The vehicle has four module communication networks: the controller area network (CAN) communications network, the standard corporate protocol (SCP), which is an unshielded twisted pair cable data bus plus and data bus minus, the universal asynchronous receiver-transmitter (UART)-based protocol (UBP) communications network, a single wire network and the international standards organization (ISO) 9141 communications network, which is a single wire network. All four networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one smart tester to be able to diagnose and control any module on the two networks from one connector. The DLC can be found under the instrument panel between the steering column and the radio.
The CAN communications network is a high speed communication network used for powertrain communication. The CAN communication network will 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, or if some but not all termination resistors are lost.
The SCP communications network will 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, or if some but not all termination resistors are lost.
The ISO 9141 communications 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 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 is different from the ISO communication network in that it allows intermodule communication.
Some modules must be programmed as part of the repair procedure. If this procedure is not followed the module will not function correctly and may set a number of DTCs, including B2477 or P1639, which indicate that some necessary data has not been programmed into the module.
Modules that need programming should not be exchanged between vehicles. In most cases the parameter values or settings are unique to that vehicle, and if not set correctly will cause concerns or faults.
Worldwide Diagnostic System (WDS) will automatically attempt to retrieve the module configuration information from all modules when vehicle ID is carried out. If the module does not contain correct information, the diagnostic tool will either request "As-Built" data or display a list of items that will need to be manually configured. The diagnostic tool will program the module based on the data entered.
For additional WDS/diagnostic tool programming procedures, refer to PROGRAMMABLE MODULE INSTALLATION (PMI) .
There are three different methods that are used for module programming
- programmable module installation
- calibration update
- programmable parameters
Some modules do not support all three methods.
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 diagnostic tool.
Normal Operation
The ABS/TC module or stability assist module communicates with the diagnostic tool through the SCP communications network circuits 4-CF6 (GY) and 5-CF6 (BU). 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 4-CF6 (GY) and 5-CF6 (BU) between the ABS/TC C135 or stability assist module C155 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 4-CF6 (GY) or 5-CF6 (BU), damage to the DLC C251, damage to the ABS/TC C135 or stability assist module C155, a problem in the in-line auxiliary junction box (AJB) C283c, C283d or joint connector No. 4 C223.
The FEM communicates with the diagnostic tool through the SCP communications network circuits 4-EG11 (GY) and 5-EG11 (BU). 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 4-EG11 (GY) and 5-EG11 (BU) between the FEM C201c and the 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 circuits 4-EG11 (GY) and 5-EG11 (BU), damage to the DLC C251, damage to the FEM C201c, or a problem in the in-line joint connectors interior auxiliary junction box (AJB) C283c, C283d or joint connector No. 4 C223.
The RCM communicates with the diagnostic tool through the ISO 9141 communications network circuit 4-EE1 (GY/RD). If circuit 4-EE1 (GY/RD) becomes open or shorted to ground communications to that module will not be possible. Check circuit 4-EE1 (GY/RD) 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 4-EE1 (GY/RD), damage to the DLC C251, in-line C212 or damage to the RCM C310a.
The instrument cluster communicates with the diagnostic tool through the SCP communications network circuits 4-EG7 (GY/RD) and 5-EG7 (BU/RD). 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 4-EG7 (GY/RD) and 5-EG7 (BU/RD) between the instrument cluster C220b 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 4-EG7 (GY/RD) and 5-EG7 (BU/RD), damage to the DLC C251, joint connector No. 4 or damage to the instrument cluster C220b.
The PCM communicates with the modules through the standard corporate protocol (SCP) communications network. Circuits 4-RE8 (GY) and 5-RE8 (BU) receive and transmit data from the PCM to the modules. Degraded SCP performance occurs if one bus line is open, shorted to ground or voltage, or if one but not all termination resistors are lost.
The DATC module communicates with the diagnostic tool through the SCP communications network circuits 4-FA10 (GY/BK) and 5-FA10 (BU/YE). 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 4-FA10 (GY/BK) and 5-FA10 (BU/YE) between the DATC module C228a 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 4-FA10 (GY/BK) or 5-FA10 (BU/YE), damage to the DLC C251, the DATC module C228a, or in joint connector No. 4 C223.
The ACM module communicates with the diagnostic tool through the SCP communications network circuits 4-EG10 (GY/BK) and 5-EG10 (BU/YE). 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 4-EG10 (GY/BK) and 5-EG10 (BU/YE) between the ACM C240c and the 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 circuits 4-EG10 (GY/BK) and 5-EG10 (BU/YE), damage to the DLC C251, the ACM C240c, or in joint connector No. 4 C223.
The PCM communicates with the diagnostic tool through the controller area network (CAN) circuits 4-EC7 (GY/RD) and 5-EC7 (BU/RD). 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 4-EC7 (GY/RD) and 5-EC7 (BU/RD) between the PCM C175a 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 4-EC7 (GY/RD) or 5-EC7 (BU/RD), damage to the DLC C251, or damage to the PCM C175a.
The DSM communicates with the diagnostic tool through the SCP communications network circuits 4-AH80 (GY/WH) and 5-AH80 (BU/OG). If circuit 4-AH80 (GY/WH) or 5-AH80 (BU/OG) becomes open or shorted to ground, communications to that module will not be possible. Check circuits 4-AH80 (GY/WH) and 5-AH80 (BU/OG) 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 either an open in circuit 4-AH80 (GY/WH) or 5-AH80 (BU/OG), damage to the DLC C251, damage to the DSM C341 c, or a problem with in-line interior auxiliary junction box (AJB) C283c, C283d or joint connector No. 4 C223.
The DDM communicates with the diagnostic tool through the SCP communications network circuits 4-EG13 (GY/OG) and 5-EG13 (GY/OG). 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 4-EG13 (GY/OG) and 5-EG13 (GY/OG) between the DDM C501a and the 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 circuit 4-EG13 (GY/OG) or 5-EG13 (GY/OG), damage to the DLC C251, damage to the DDM C155a, or a problem in the interior auxiliary junction box (AJB) C283c, C283d or joint connector No. 4 C223.
The REM communicates with the diagnostic tool through the SCP communications network circuits 4-EG12 (GY/WH) and 5-EG12 (BU/OG). 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 4-EG12 (GY/WH) and 5-EG12 (BU/OG) between the in-line joint connectors C283b, C283d or C223 and the 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 circuits 4-EG12 (GY/WH) and 5-EG12 (BU/OG), damage to the DLC C251, damage to the REM 420b, or a problem in the interior auxiliary junction box (AJB) C283c, C283d or joint connector No. 4 C223.
The navigation system module communicates with the diagnostic tool through the SCP communications network circuits 4-EG17 (GY/BK) and 5-EG17 (BU/YE). 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 4-EG17 (GY/BK) and 5-EG17 (BU/YE) between the navigation system module C4209 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 circuit 4-EG17 (GY/BK) and 5-EG17 (BU/YE), damage to the DLC C251, damage to the navigation system module C4209, or a problem in the interior auxiliary junction box (AJB) C283c, C283d, joint connector No. 5 C427 or joint connector No. 4 C223.
The driver temperature controlled seat module communicates with the diagnostic tool through the UBP communications network circuit 4-HC21 (GY/OG). If circuit 4-HC21 (GY/OG) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 4-HC21 (GY/OG) between the temperature controlled seat module and the 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 circuit 4-HC21 (GY/OG), damage to the DLC C251, damage to the driver temperature controlled seat module C3031 a, or a problem in the in-line connectors C213, C315 or joint connector No. 1 C261.
The passenger temperature controlled seat module communicates with the diagnostic tool through the UBP communications network circuit 4-HC22 (GY). If circuit 4-HC22 (GY) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 4-HC22 (GY) between the passenger temperature controlled seat module and the 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 circuit 4-HC22 (GY), damage to the DLC C251, damage to the passenger temperature controlled seat module C3031 a, or a problem in the in-line connectors C213, C313 or joint connector No. 1 C261.
The anti-lock brake system/traction control (ABS/TC) module or stability assist module, dual automatic temperature control (DATC) module, audio control module (ACM), rear electronic module (REM), front electronic module (FEM), electronic parking brake module, driver seat module (DSM), driver door module (DDM), navigation system module, and the instrument cluster communicate with the diagnostic tool through the SCP communications network circuits. The powertrain control module (PCM) communicates with all modules on the SCP network. 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 the SCP communications network circuits between the PCM C175a, ACM C240c, ABS/TC control module C135 or stability assist module C155, DATC module C228a, instrument cluster C220b, navigation system module C4209, electronic parking brake module C4205b, DDM C501 a, DSM CC341 c, FEM C201 c, REM C420b, 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 one or both SCP communications network circuits, damage to the PCM C175a, ACM C240c, ABS/TC control module C135, stability assist module C155, DATC module C228a, instrument cluster C220b, navigation system module C4209, electronic parking brake module C4205b, DDM C501a, DSM CC341c, FEM C201c, REM C420b, inline C315, joint connector No. 4 C223, interior auxiliary junction box (AJB) C283a, C283b, C283c, C283d, joint connector No. 5 C427 and the DLC C251. 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 diagnostic tool data link 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 RCM communicates with the diagnostic tool through the ISO 9141 communications network circuit 4-EE1 (GY/RD). If circuit 4-EE1 (GY/RD) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 4-EE1 (GY/RD) 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 either an open in circuit 4-EE1 (GY/RD), damage to the DLCC251, in-line C212 or damage to the C310a.
The driver climate control seat module, passenger climate control seat module and parking aid module communicate with the diagnostic tool through the UART based-protocol (UBP) communications network circuit 4-ED6 (OG). If circuit 4-ED6 (OG) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 4-ED6 (OG) between the driver climate control seat module, passenger climate control seat module, parking aid module and the 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 circuit 4-ED6 (OG), damage to the DLC C251 or damage to the driver or passenger climate control seat module, parking aid module, or a problem in one of the in-line connectors C213 or joint connector No. 1 C261. If, after individual checks of each circuit leading to a module show resistance values less than 5 ohms and no in-line connector issues are 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 electronic parking brake module communicates with the diagnostic tool through the SCP communications network circuits 4-CG16 (GY/RD) and 5-CG16 (BU/RD). 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 4-CG16 (GY/RD) and 5-CG16 (BU/RD) between the electronic parking brake module C4205b 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 circuit 4-CG16 (GY/RD) and 5-CG16 (BU/RD), damage to the DLC C251, damage to the electronic parking brake module C4205b, or a problem in the interior auxiliary junction box (AJB) C283b, C283d, joint connector No. 5 C427 or joint connector No. 4 C223.
The parking aid module communicates with the diagnostic tool through the UBP communications network circuit 4-GN10 (GY). If circuit 4-GN10 (GY) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 4-GN10 (GY) between the parking aid module C4014b and the 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 circuit 4-GN10 (GY), damage to the DLC C251, damage to the parking aid module C4014b, or a problem in the in-line connector C213 or joint connector No. 1 C261.
Under normal operation the diagnostic tool is connected to the DLC C251 to communicate with the standard corporate protocol (SCP), UART based protocol (UBP), and the 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, circuit 29-ED6 (OG/YE) must be checked for voltage and 31-ED6 (BK), and 91-ED6 (BN) must be checked for an open condition.
The FEM controls RH exterior mirrors, power adjustable pedals, both interior and exterior lighting active anti-theft functions and the brake shift interlock. Power is supplied through the central junction box (CJB) fuse 20 (10A) and fuse 30 (5A) on Circuits 29-DK20 (OG/GN), 29-DK21 (OG/WH) and grounded through circuit 31-DK20 (BK/RD), 31-DK20A (BK/RD), 31-DK20B (BK/RD), 31-DK20C (BK/RD) and 31-DK20D (BK/RD).
The power driver seat is controlled by the DSM. Power is supplied through central junction box (CJB) fuse 7 (5A) and battery junction box (BJB) fuse 21 (20A) on Circuits 29-AH80 (OG/WH) and 30-AH80 (RD). The DSM is grounded through circuits 31-AH80 (BK) and 91-AH80 (BN/WH).
The LH exterior mirror, keyless entry and power locks are controlled by the DDM. Power is supplied through central junction box (CJB) fuses 7 (5A) and 22 (10A) on circuits 29-AJ80 (OG) and 29S-AJ86 (OG/BU) and grounded through circuits 91-AJ80 (BN/BU) and 31-AJ80B (BK/OG).
The exterior lights, interior lights and active anti -theft functions are controlled by the REM. Power is supplied through central junction box (CJB) fuse 20 (10A) on circuit 29-DK31 (OG/BK), and grounded through circuit 31-DK30D (BK/OG), 31-DK30E (BK/OG), 31-DK30F (BK/OG), 31-DK30G (BK/OG) and 31-DK30H (BK/OG).