Description & Operation

Module communications network consists of several modules working together through 2 module communications networks, referred to as Standard Corporate Protocol (SCP) network and International Standards Organization (ISO) network. SCP and ISO networks provide ability for module-to-module communications by sharing inputs and outputs instead of each component having to be wired directly to each module. Both networks are connected to Data Link Connector (DLC) to aid in diagnosing and testing of both networks. This article is used to diagnose SCP and ISO communications network circuit faults.

Modules of International Standards Organization (ISO) diagnostic communications network are connected to a single wire, or circuit No. 70 (Light Blue/White wire). ISO network will not function if single wire becomes shorted to ground or power. ISO network modules consist of Parking Aid Module (PAM), Restraint Control Module (RCM), Left Power Sliding Door Module (LPSDM) and Right Power Sliding Door Module (RPSDM), if equipped.

SCP is a bus network, consisting of a pair of twisted wires to transfer information between all modules. SCP bus network consists of a twisted pair of wires, positive (+) circuit No. 914 (Tan/Orange wire) and a negative (-) circuit No. 915 (Pink/Light Blue wire), which would allow network communications to continue if one of bus circuits should fail. SCP bus network is routed throughout vehicle to Powertrain Control Module (PCM), Anti-Lock Brake System (ABS) control module, Front Electronic Module (FEM), Rear Electronic Module (REM), Instrument Cluster Module (ICM), New Generation Speed Control (NGSC) module and Remote Keyless Entry (RKE) module (if equipped). The following is a listing of all modules of module communication network, with a brief description of module functions and capabilities. For module locations, see COMPONENT LOCATIONS  .

• Anti-Lock Brake System Control Module
  
  ABS module is connected to SCP network. ABS module controls brake system by regulating brake fluid pressure to prevent wheels from locking and skidding when braking. ABS module also is used for traction control by preventing wheelspin by applying brake fluid pressure to appropriate front brake and restoring traction when driving in slippery or loose gravel situations.
• Front Electronic Module
  
  FEM is connected to SCP network. FEM controls power door lock functions for driver's door only, active anti-theft, blower motor, front exterior lamps, interior lamps, front and rear windshield wipers. Receives signals from RKE module and communicates to SCP with Rear Electronic Module (REM).
• Instrument Cluster Module
  
  ICM is connected to SCP network. ICM displays driver information in gauges and meters of instrument cluster. ICM may also contain message center (optional), which displays lamp outage and door/hatch ajar information.
• New Generation Speed Control Servo
  
  NGSC servo is connected to SCP network. When activated, NGSC servo controls vehicle speed during cruise control operation, by actuating throttle linkage.
• Passive Anti-Theft System
  
  PATS is integral of Powertrain Control Module (PCM). PATS is designed to disable vehicle from starting when an unauthorized entry to vehicle is detected. PCM stores ignition key codes.
• Powertrain Control Module
  
  PCM is connected to SCP network. PCM controls engine performance, emission and on-board diagnostics. For additional information regarding PCM, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. PCM controls PATS system functions as well as illumination of anti-theft indicator. Illumination command is sent from PCM through SCP communications network to instrument cluster, which supplies power to anti-theft indicator.
• Rear Electronic Module
  
  REM is connected to SCP network. REM mainly controls rear portion of vehicle. REM controls rear exterior lights, fuel level information, auxiliary air conditioning, rear defrost, interior electronic mirror, and interior lights. REM supports other locking features for all passenger doors, Right or Left Power Sliding Door Module (RPSDM/LPSDM) and liftgate. When Power Sliding Door (PSD) operation is requested, REM determines if necessary preconditions are met, and signals appropriate PSD module for PSD operation (as equipped).
• Remote Keyless Entry
  
  RKE is connected to SCP network. RKE processes signals from remote transmitters and commands from driver's door switches. RKE also outputs messages through SCP to FEM and REM to either or both LPSPD/RPSDM for left or right power sliding door operation (as equipped).
• Restraint Control Module
  
  RCM is connected to ISO network, and may also be referred to as an air bag control module. RCM controls deployment of air bags based on sensor inputs. For additional information see appropriate AIR BAG RESTRAINT SYSTEMS article.
• Parking Aid Module
  
  PAM is connected to ISO network. PAM controls warning indicators which are triggered by sensors located in rear bumper. These sensors can advise driver of close objects, or out-of-sight objects when reversing vehicle.
• Left/Right Power Sliding Door Module
  
  LPSDM and/or RPSDM (as equipped) communicate through ISO network. These PSD modules can send and receive messages from REM and RKE modules for desired PSD operations. LPSDM/RPSDM also control automatic opening and closing of left or right power sliding door (if equipped).
• Switched System Power Feature
  
  SSP feature removes power from relays to prevent excessive draw on vehicle battery. After 30 minutes or more, with all accessories and equipment off, SSP feature removes power to necessary SSP relays, conserving battery energy. A fault in SSP feature could cause some module communication network functions to be inoperative. Always verify SSP feature is properly operating prior to condemning any component, network or system.