Principles of Operation (How Does It Work)

Tachometer
Engine RPM information is relayed to the instrument cluster (also referred to as the Hybrid Electronic Instrument Cluster [HEC]) from the Powertrain Control Module (PCM) via the SCP network.

LOW FUEL Level Indicator
The low fuel level indicator is hardwired from the fuel sender to the instrument cluster. The instrument cluster will illuminate the low fuel indicator when the usable fuel quantity is less than 1/8 tank (15%) of fuel tank capacity.

Speedometer Gauge
The instrument cluster receives the vehicle speed signal from PCM over the SCP network and displays it on the speedometer gauge. If the instrument cluster receives no vehicle speed signal after one second, the speedometer defaults to 0.0 km/h (0.0 mph).

Fuel Gauge
The fuel sender is hardwired to the fuel gauge. When the instrument cluster fails to receive the fuel level signal for more than 33 seconds, the fuel level gauge will move below E (empty). If the fuel level signal operates correctly for more than 33 seconds, the fuel gauge will return to the correct position.

Fuel fills of less than 9.5 liters (2.5 gallons) require at least 10 minutes to update the fuel gauge indication.

Engine Coolant Temperature Gauge
Engine coolant temperature information is received by the instrument cluster from the PCM over the SCP network. Engine coolant temperatures above 121°C (250°F) will cause the gauge to indicate above the normal band. If the engine coolant temperature information is missing or invalid for five seconds, the temperature gauge will indicate below the cold (C) position.

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

Low Engine Coolant Indicator
The low engine coolant indicator is hardwired from the low engine coolant switch to the instrument cluster. When low engine coolant is detected, the low engine coolant switch will close, thus grounding the low engine coolant switch input to the instrument cluster and causing the low engine coolant indicator to illuminate.

Refilling the engine coolant will cause the low engine coolant switch to open and the indicator to turn off at the initiation of the next ignition switch cycle.

Odometer
The instrument cluster receives odometer message from the PCM and stores the mileage in memory. When the instrument cluster fails to receive the odometer message for more than two seconds, the odometer will display dashes.

Oil Pressure Gauge
The oil pressure gauge is hardwired from the oil pressure switch to the instrument cluster. The oil pressure gauge will indicate either normal or no oil pressure.

BRAKE Warning Indicator
The BRAKE warning indicator activates when the Generic Electronic Module (GEM) detects the ignition switch circuits are in the RUN state, when the GEM detects low brake fluid level or that the parking brake is applied, from the brake input circuit. The BRAKE warning indicator will prove out starting when the GEM detects the ignition circuits make a transition to RUN or START from OFF, ACC, or keyout and ending when either three seconds have elapsed or when the GEM detects the ignition circuits make a transition to OFF, ACC, or keyout.

Safety Belt Warning Indicator
The seat belt switch is hardwired to the GEM. The safety belt warning indicator will be illuminated when the GEM sends a ground signal to the instrument cluster.

ABS Warning Indicator
The ABS indicator will be illuminated when the anti-lock brake control module sends a ground signal to the instrument cluster. The prove out of the ABS indicator is controlled by the anti-lock brake control module.

SERVICE ENGINE SOON indicator
After the engine is started, the SERVICE ENGINE SOON indicator will prove out for a duration of three seconds. If the instrument cluster does not receive a message from the PCM within five seconds, the instrument cluster will illuminate the SERVICE ENGINE SOON indicator and log a Diagnostic Trouble Code (DTC).

High Beam Indicator
The high beam indicator will illuminate when the multifunction switch is in the high beam position by sending a battery signal to the instrument cluster.

Right and Left Turn Indicator
The right and left turn indicators will illuminate when the multifunction switch is in either turn signal position or hazard lamps position by sending a battery signal to the instrument cluster.

AIR BAG Warning Indicator
The AIR BAG warning indicator will be illuminated when the restraint control module (RCM) sends a ground signal to the instrument cluster. The prove out of the AIR BAG warning indicator is controlled by the RCM.

THEFT Indicator
The THEFT indicator provides Passive Anti-Theft System (PATS) prove out. The THEFT indicator will prove out for three seconds following the ignition switch cycle and will flash following an ignition switch OFF transition to indicate that PATS is active.

Charging System Indicator
The charging system indicator will be illuminated when the generator sends a ground signal to the instrument cluster.

Overdrive Off (O/D OFF) Indicator
The O/D OFF indicator is controlled by the off/on message sent from the PCM via the SCP. The instrument cluster does not prove out the O/D OFF indicator.

Traction Control Indicator
During initialization, the instrument cluster will receive the Traction Control (TC) system state status message to determine if the vehicle is TC equipped. If the vehicle is TC equipped, this information will be stored in KAM and the indicator will be proved out for three seconds during each ignition cycle. If this message is not received (within 5O0ms), the instrument cluster will send the request TC system state status message. If there is no response to this message after two attempts, the cluster will assume that the vehicle is not TC equipped and the indicator will remain off. When a TC event is occurring, the instrument cluster will receive a TC active command on message and illuminate the TC indicator until receiving the TC indicator off message.

In the event of a TC failure, the TC indicator will remain off and the ABS indicator will illuminate.