J1850 COMMUNICATION NETWORK
The Powertrain Control Module (PCM), Passive Anti-Theft System (PATS) module and Remote Climate Control (RCC) module are connected to the J1850 module communication network. The modules on the J1850 network can communicate with any other module on the network or a scan tool connected to Data Link Connector (DLC).
The J1850 module communication network bus circuits consist of a pair of twisted wires is used to transfer information between each module. The bus consists of a (+) circuit No. 914 and a (-) circuit No. 915. The bus is routed throughout the vehicle to each module on the J1850 network. (Scheme 15) The network will continue to operate even if one bus wire is open, or shorted to power or ground, or if one or more modules fail. If any of these failures occurs, a DTC will set.
Scheme 15
ISO 9141 COMMUNICATION LINK
The Generic Electronic Module (GEM), Anti-lock Brake System (ABS) control module, Remote Anti-theft Personality (RAP) module, air bag diagnostic monitor and Semi-Active Ride Control (SARC) module are connected to the ISO 9141 communication link. The ISO 9141 communication link is not a true network in the fact that the modules can only communicate with a scan tool connected to Data Link Connector (DLC) and cannot communicate with the other modules.
The ISO 9141 communication link circuit consists of a single Light Blue/White wire routed throughout vehicle. (Scheme 16) Data is transferred only from each module to scan tool. If the Light Blue/White wire becomes open or shorted, or if a module fails, communication link will fail.
| Component | Location |
|---|---|
| ABS Module | Under Battery In Engine Compartment |
| Air Bag Diagnostic Monitor | In Center Of Instrument Panel |
| GEM | On Rear Of Fuse Panel |
| PATS Module | Behind integrated Control Panel |
| PCM | On Right Side Of Firewall In Engine Compartment |
| RAP Module | In Center Of Instrument Panel |
| RCC Module | On A/C Evaporator Case |
| SARC Module | Right Side Of Luggage Compartment |
COMPONENT LOCATIONS
Scheme 16
EQUIPMENT HOOK-UP
Note. Manufacturer recommends using New Generation Star (NGS) scan tester for diagnosis of module communications network.
- Ensure ignition switch is in OFF position. Select proper program card for scan tester for vehicle application. With scan tester facing away from you, insert program card into slot on scan tester. Ensure program card is properly inserted into scan tester or scan tester will not operate.
- Connect scan tester to the 16-terminal Data Link Connector (DLC). see scheme 3 The DLC is a located below driver's side of instrument panel, to the right of steering column.
- Connect scan tester power cable to battery source or cigarette lighter socket. Turn ignition switch to ON position. Scan tester automatically performs an initialization test. Initialization test checks the scan tester memory and verifies that vehicle interface module matches program card for scan tester. If an error message is now displayed on scan tester, refer to NGS scan tester operator manual for system messages.
- The menu item VEHICLE AND ENGINE SELECTION should be highlighted on scan tester. Press trigger to select VEHICLE AND ENGINE SELECTION.
- Rotate dial on scan tester to menu item SELECT NEW VEHICLE MODEL AND YEAR. Press trigger to select VEHICLE AND ENGINE SELECTION. Select model year, vehicle and engine size by rotating dial to highlight the selection, then press trigger to select. If selected vehicle is not displayed, repeat this step.