Description & Operation

WARNING: Deactivate air bag system before performing any service operation. See appropriate AIR BAG RESTRAINT SYSTEMS article. Do not apply electrical power to any component on steering column without first deactivating air bag system. Air bag may deploy.

NOTE: Anti-Lock Brake System (ABS) control module is referred to as a Stability Assist Module (SAM) if vehicle is equipped with traction control and stability assist. Next Generation Speed Control (NGSC) servo is an integral part of the Powertrain Control Module (PCM). Message Center Module (MCM) is an integral part of the instrument cluster. Steering Column Lock Module (SCLM) may also be referred to as a Steering Column Lock Unit (SCLU) or steering column lock.

NOTE: When instrument cluster is replaced, Passive Anti-Theft System (PATS) must be reconfigured. For programming and reconfiguring procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.

Instrument cluster consists of an electronically driven analog speedometer and one message center display. Also contained within the instrument cluster is a fuel gauge, temperature gauge, transmission range indicator, tachometer and various warning and indicator lights.

Instrument cluster gauges, warning lights and message center displays are either controlled and driven directly by specific components or the information is requested and received through the Standard Corporate Protocol (SCP) network. The instrument cluster has self-diagnostic capabilities. One or more Diagnostic Trouble Code (DTC) can be stored in the event of malfunction. DTCs can be retrieved using a New Generation Star (NGS) tester or other generic scan tools, although not all scan tools will be capable of performing all necessary functions.

The instrument cluster receives most of its signals through the SCP network. It is important to ensure the module communications system is operating properly and that each module is receiving the correct signal from the appropriate component. It is very important to understand where command messages originate from, which modules can send command messages, which modules receive command messages and what control module requested command message operations. The instrument cluster receives the following signals though the SCP network.

Washer fluid level, high beam, parking brake, brake fluid level, low oil pressure and front door ajar signals from the Front Electronic Module (FEM).
Fuel level and rear door ajar signals from the Rear Electronic Module (REM).
Turn/hazard and light outage signals from the FEM and REM.
Charging system, Malfunction Indicator Light (MIL), cruise control, cylinder head temperature, engine coolant temperature, engine speed, check fuel cap and transmission range signals from the Powertrain Control Module (PCM).
AIR BAG signal from the Restraints Control Module (RCM).
Vehicle speed, trip, odometer, brake system operation and traction control system signals from the Anti-Lock Brake System (ABS) control module.
Steering column lock signal from the Steering Column Lock Module (SCLM).