Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Description & Operation: Notes
The module communications network provides the ability for a module-to-module communication by sharing inputs and outputs instead of each component having an input and output wired directly to each module. A BUS which consists 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 Powertrain Control Module (PCM), Electronic Automatic Temperature Control (EATC) module, and Natural Gas Vehicle (NGV) module (if equipped). See Fig 1. Terminal No. 7 (Light Blue/White wire) on DLC is routed through vehicle to Lighting Control Module (LCM), Anti-Lock Brake System (ABS) Module, Air Bag Diagnostic Monitor, and Driver's Door Module (DDM). This wire is referred to as the ISO 9141 communication link circuit No. 70 and provides a means for the scan tester to communicate with these modules using the DLC. For module locations, see COMPONENT LOCATIONS TABLE. In the event that a system failure exists, a Diagnostic Trouble Code (DTC) will be stored in the module. A New Generation Star (NGS) scan tester and Data Link Connector (DLC) may be used for retrieving and clearing DTCs from the module. DTC may be used for system diagnosis.
| Component | Location |
|---|---|
| Air Bag Diagnostic Monitor | Behind Instrument Panel To Right Of Steering Column |
| Anti-Lock Brake System (ABS) Control Module | Left Front Of Engine Compartment, On Front Of Upper Radiator Support |
| Data Link Connector (DLC) | Below Driver's Side Of Instrument Panel, To Right Of Steering Column |
| Driver's Door Module (DDM) | Inside Driver's Door |
| Electronic Automatic Temperature Control (EATC) Module | On A/C Evaporator Core Housing At Passenger's Side Of Vehicle |
| Natural Gas Vehicle (NGV) Module | Front Of A/C Condenser Behind Radiator Grille |
| Powertrain Control Module (PCM) | Below Driver's Side Of Instrument Panel, To Left Of Steering Column |
| Lighting Control Module (LCM) | Behind Driver's Side Of Instrument Panel, To Right Of Steering Column |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.