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Principles of Operation
The vehicle has three module communication networks: the standard corporate protocol (SCP), which is an unshielded twisted pair cable (data bus plus, (Circuit 914 [TN/OG]) and data bus minus, (Circuit 915 [PK/LB]), the single wire circuit 693 (OG) universal asynchronous receiver-transmitter (UART) based protocol (UBP) communications network and the international standards organization (ISO) 9141 communications network, which is a single wire network (Circuit 70 [LB/WH]). Both 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 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.
The vehicle security module controls the remote keyless entry system and computer-operated lock system. For additional information, refer to HANDLES, LOCKS, LATCHES AND ENTRY SYSTEMS .
The driver seat module (DSM) allows automatic positioning of the memory driver seat, both outside memory mirrors and the memory pedals to three programmable positions. For additional information, refer to SEATING .
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Refer to COMPUTER DATA LINES wiring diagrams for schematic and connector information.
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- Verify the customer concern by operating the system.
- Visually inspect for obvious signs of electrical damage.
- If the concern remains after the inspection, connect the diagnostic tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle: check that the program card is correctly installed. check the connections to the vehicle. check the ignition switch position. If the diagnostic tool still does not communicate with the vehicle, GO to «PINPOINT TEST Q»(ref-193023-S09495954382005092300000) .
- GO to «PINPOINT TEST PC»(ref-193023-S26710846092005110300000) .
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Normal Operation
The VAPS module communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) between the VAPS module C2231b 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 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, damage to the VAPS module C2231b, or a problem in the in-line connector C212.
The vehicle security module communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 693 (OG). If circuit 693 (OG) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 693 (OG) between the vehicle security module C3008f 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 693 (OG), damage to the DLC C251, damage to the vehicle security module C3008f, or a problem in the in-line connector C212.
The 4WD control module communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 693 (OG). If circuit 693 (OG) becomes open or shorted to ground communications to that module will not be possible. Check circuit 693 (OG) between the 4WD control module C281b 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 693 (OG), damage to the DLC C251, damage to the 4WD control module C281b, or a problem in the in-line connectors C212 or C311.
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 tire pressure monitor module communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) between the tire pressure monitor module C3183 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 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, damage to the tire pressure monitor module C3183, or a problem in the in-line connector C212.
The DSM communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 693 (OG). If circuit 693 (OG) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 693 (OG) between the DSM C341g 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 693 (OG), damage to the DLC C251, damage to the DSM C341g, or a problem in the in-line connector C212.
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 C4014 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 C4014, or a problem in the in-line connector C212 or C408.
The PCM communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) 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 circuit 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, damage to the PCM C175b, or a problem in the in-line connector C263.
The instrument cluster communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) 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 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, or damage to the instrument cluster C220b.
The DEATC module communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) between the DEATC module C228b 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 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, or damage to the DEATC module C228b.
The ABS/TC module or stability assist module communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) between the ABS/TC module 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 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, damage to the ABS/TC module or stability assist module C155, or a problem in the in-line connector C263.
The driver climate controlled seat module communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 693 (OG). If circuit 693 (OG) becomes open or shorted to ground communications to that module will not be possible. Check circuit 693 (OG) between the climate 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 an open in circuit 693 (OG), damage to the DLC C251, damage to the driver climate controlled seat module C3031b, or a problem in the in-line connectors C212.
The passenger climate controlled seat module communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 693 (OG). If circuit 693 (OG) becomes open or shorted to ground communications to that module will not be possible. Check circuit 693 (OG) between the passenger climate 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 an open in circuit 693 (OG), damage to the DLC C251, damage to the passenger climate controlled seat module C3036b, or a problem in the in-line connectors C212 or C316.
The navigation module communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) between the navigation 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 an open in circuit 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251 or damage to the navigation module C4209.
The powertrain control module (PCM), anti-lock brake system/traction control (ABS/TC) module or stability assist module, variable assist power steering (VAPS) module, electronic automatic temperature control (EATC) module, tire pressure monitor module, telematics control module, navigation system module and the instrument cluster communicate with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) between the PCM C175b, tire pressure monitor module C3183, ABS/TC module or stability assist module C155, VAPS C2231b, DEATC module C228b, instrument cluster C220b, navigation module C4209 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 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, damage to the PCM C175b, VAPS C2231b, tire pressure monitor module C3183, ABS/TC module or stability assist module C155, DEATC module C228b, instrument cluster C220b, navigation module C4209, a problem in the in-line connectors C212, C263 or an internal problem with the PCM, ABS/TC module or stability assist module, EATC module, tire pressure monitor module, VAPS, instrument cluster or the navigation module. 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 C212 or C408. 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 climate controlled seat module, driver seat module (DSM), vehicle security module, and the four-wheel drive (4WD) control module communicate with the diagnostic tool through the UART based protocol (UBP) communications network circuit 693 (OG). If circuit 693 (OG) becomes open or shorted to ground, communications to that module will not be possible. Check circuit 693 (OG) between the driver climate controlled seat module, passenger climate controlled seat module, DSM, vehicle security module, and the 4WD control 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 an open in circuit 693 (OG), damage to the DLC C251 or damage to the climate controlled seat module, DSM, vehicle security module, the 4WD control module, instrument cluster, or a problem in one of the in-line connectors C212 and C408. 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 instrument cluster communicates with the diagnostic tool through the UART based protocol (UBP) communications network circuit 693 (OG). If circuit 693 (OG) becomes open or shorted to ground communications to that module will not be possible. Check circuit 693 (OG) between the 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 693 (OG), damage to the DLC C251, damage to the instrument cluster C220b.
Under normal operation the diagnostic tool is connected to the DLC C251 to communicate with the standard corporate protocal (SCP), 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 damaged. If the diagnostic tool and the DLC C251 are OK, circuits 1001 (WH/YE), 57 (BK), and 570 (BK/WH) must be checked for an open condition.
The power driver seat and power outside rear view mirrors are controlled by the DSM only when the vehicle is equipped with the programmable/recall memory option. Power is supplied through central junction box (CJB) fuse 2 (10A) and battery junction box (BJB) fuse 21 (30A) on Circuits 1003 (GY/YE), 566 (DG) and grounded through circuit 1203 (BK/LB) and 1205 (BK).
The vehicle security module controls the remote keyless entry and computer-operated locks and vehicle security. The vehicle security module receives power through BJB fuse 2 (30A) and CJB fuse 2 (10A). From the fuses power is delivered to the module through circuits 456 (DG/OG), 645 (WH/LB) and is grounded on circuit 1205 (BK).