Instrument Cluster

NOTE: A new instrument cluster must be reconfigured.

The Instrument Cluster Module (ICM) is a Hybrid Electronic Cluster (HEC). The instrument cluster uses both hardwired and the Standard Corporate Protocol (SCP) communication network to transmit and receive information. As a technician it is very important to understand:
- where the input originates from.
- all the information necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- does the module which received the input control the output of the feature, or does it output a message over the SCP network to another module?
- which module controls the output of the feature.

The instrument cluster carries out a display prove-out to verify that the warning/indicator miniature bulbs for monitored systems are functioning correctly. When the ignition switch is in the ON position with the engine off, the following warning indicators will prove out:
- Anti-lock Brake (ABS) warning indicator
- air bag warning indicator
- BRAKE warning indicator
- charging system indicator
- CHECK FUEL CAP indicator
- CHECK GAGE warning indicator
- THEFT indicator

Gauge Indication Systems
The gauge indication systems use air-core type gauges mounted in the instrument cluster. No adjustment, calibration, or maintenance is necessary for any of the gauges. The gauges cannot be installed separately.

Instrument Cluster
When installing a new instrument cluster, contact the Instrument Cluster Program.

Speedometer
The instrument cluster receives the vehicle speed signal from the Powertrain Control Module (PCM) via the standard corporate protocol (SCP) network and displays it on the speedometer. If the instrument cluster receives no signal the speedometer will default to 0.0 km/h (0.0 mph).

LED Display-Standard Cluster
The LED display houses the odometer, trip odometer and an optional compass and outside air temperature display. The primary odometer shows the cumulative miles and displays the mileage up to one million miles. The trip odometer is a tenths odometer and displays the mileage up to one thousand miles. The compass provides the vehicles directional bearing relative to the magnetic north.

Tachometer
The tachometer is electrically operated and indicates engine speed in revolutions per minute (rpm). The tachometer range is 0 to 7,000 rpm. The tachometer receives the signal via the SCP network from the PCM. If the rpm information sent to the instrument cluster is invalid or missing, the instrument cluster will default the tachometer to 0.0 rpm.

Fuel Gauge
The fuel gauge receives its signal from the fuel level sensor, part of the fuel pump module. The fuel level sensor measures variable resistance in the fuel tank depending on the current fuel level. If the fuel level is low, the resistance of the fuel level sensor is low. If the fuel level is high, the resistance of the fuel level sensor is high. Basic fuel level indication is the same for both gasoline and flex-fuel vehicles, except that the flex-fuel vehicles incorporate the use of a flex-fuel module. The flex-fuel module is a DC-AC-DC interface, used to prevent reactions created by the interaction of DC current with the fuel. The flex-fuel module is part of the fuel pump module and is installed as an assembly.

Temperature Gauge
The instrument cluster receives the engine coolant temperature signal from the PCM via the SCP network and displays the information on the temperature gauge. If the instrument cluster receives no signal the temperature gauge will default to the cold position.

Oil Pressure Gauge
The low oil pressure warning gauge is hardwired to the oil pressure switch. The oil pressure switch is a normally open switch that is installed in the engine block and consists of a diaphragm and contact points. The contact points are closed with oil pressure causing the gauge to indicate normal oil pressure. With no oil pressure, the contacts open and the gauge indicates low oil pressure.

Voltmeter Gauge
The voltage gauge displays the system voltage as measured at the instrument cluster run input.

Charging System Indicator
The instrument cluster microprocessor receives the charge signal from the PCM via the SCP network. When the generator output is insufficient to maintain the battery state of charge the instrument cluster will illuminate the charging system indicator.

Air Bag Warning Indicator
The air bag warning indicator is hardwired to the restraint control module. When the Supplemental Restraint System (SRS) is operating correctly the air bag warning indicator illuminates for approximately six seconds when the ignition switch is turned on. It only remains illuminated after starting if a SRS malfunction is present.

SERVICE ENGINE SOON Indicator
During vehicle operation, the SERVICE ENGINE SOON indicator lamp illuminates when the PCM has detected a fault. If a fault is detected the PCM sends a signal to the instrument cluster via the SCP line and turns on the SERVICE ENGINE SOON indicator lamp.

High Beam Indicator
The high beam indicator is hardwired to the steering column multifunction switch via the high beam relay and illuminates when the headlamps are placed in the high beam position or the flash-to-pass position.

Turn Indicator
The RH or LH turn indicators are hardwired to the steering column multifunction switch and illuminate intermittently relative to the position of the turn signal switch on the steering column.

BRAKE Warning Indicator
The BRAKE system warning indicator has multiple functions. It illuminates when the parking brake is applied, when the brake fluid level is low, or when a fault is detected in the anti-lock brake system (ABS). It utilizes hardwired circuitry, the SCP network and the instrument cluster micro processor.

Anti-Lock Brake Warning Indicator (ABS)
The anti-lock brake warning indicator (ABS) illuminates when the anti-lock brake control module detects a fault in the system. If a fault is detected, the anti-lock brake control module sends a ground signal to the instrument cluster via hardwired circuitry and the instrument cluster illuminates the ABS warning indicator.

Safety Belt Warning Indicator
The safety belt warning indicator illuminates when the driver safety belt is not fastened. The driver safety belt switch (part of the buckle) provides the input for the Generic Electronic Module (GEM) by grounding the circuit when the safety belt is disconnected. The GEM provides the appropriate signal to the instrument cluster and illuminates the bulb depending on the safety belt switch position.

THEFT Indicator
The THEFT indicator, located in the instrument cluster, is controlled by a hardwired signal sent to instrument cluster from the PCM.

4x4 HIGH Indicator Lamp
The 4x4 HIGH indicator is hardwired to the Four Wheel Drive (4WD) module. When four wheel drive high is selected the 4WD module will provide a ground signal to the instrument cluster. The instrument cluster, upon the receipt of the ground signal, will illuminate the 4x4 HIGH indicator.

4x4 LOW Indicator Lamp
The 4x4 LOW indicator receives its signal from the PCM via the standard SCP network. When four wheel drive low is selected, the transmission control module will provide a signal to the PCM which then provides a ground signal to the instrument cluster. The instrument cluster, upon the receipt of the signal from the PCM illuminates the 4x4 LOW indicator.

Speed Control Indicator (if equipped)
When the speed control is enabled, the PCM signals the instrument cluster processor via the SCP network. The instrument cluster, upon the receipt of the signal from the PCM provides a ground for the speed control indicator.

DOOR AJAR Indicator
The DOOR AJAR indicator is hardwired to the GEM and will illuminate when any of the doors, or the liftgate, are opened. The GEM receives its signal from the central security module via the UART Based Protocol (UBP) line.

CHECK GAGES Warning Indicator
The CHECK GAGES warning indicator monitors the fuel level, coolant temperature and the engine oil pressure. The indicator will illuminate if the remaining fuel is less than approximately two gallons or 1/10 of a tank, if the SCP coolant temperature data is missing or invalid, if the engine temperature reaches 121°C (249.8°F) or higher, or if the engine oil pressure is low.

O/D OFF Indicator (if equipped)
The O/D OFF indicator will illuminate when the transmission overdrive has been turned off. The instrument cluster receives a switch status signal via the SCP network from the PCM.

CHECK FUEL CAP Indicator
The CHECK FUEL CAP indicator receives its signal from the PCM via the SCP network.