Principles of Operation (How Does It Work)

Tachometer
Engine speed information is relayed to the instrument cluster from the Powertrain Control Module (PCM) via the Standard Corporate Protocol (SCP) network.

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

Fuel Gauge
The instrument cluster receives the fuel level information from the fuel sender unit (part of the fuel pump module). This is a variable resistor which varies the ground supply to the gauge. When the fuel level is low, the resistance is low, when the fuel level is high the resistance is high. If an invalid input signal is received, the fuel gauge will then default to below the empty position. The fuel level input signal is heavily damped to allow for movement of fuel in the tank when the ignition switch is in the ON position.

Temperature Gauge
Engine coolant temperature information is received by the instrument cluster from the PCM over the SCP network. If the engine coolant temperature information is missing or invalid, the temperature gauge will indicate below the cold (C) position.

Odometer
The instrument cluster records the total mileage of the vehicle, using information received from the PCM and electronically displaying this information in a LCD display. If this information is not received, the LCD will display all dashes. On the LCD display there is a tripmeter which can be reset by using the reset button.

Low Fuel Warning Indicator
Incorporated into the instrument cluster is a low fuel warning indicator which illuminates when the fuel drops to a pre-determined level.

Brake Warning Indicator
The brake warning indicator has multiple functions. The brake warning indicator self-tests the system when the ignition switch is in the engine RUN position by grounding the circuit. The brake warning indicator illuminates if the brake fluid is low or if the parking brake is set. If both the Anti-Lock Brake (ABS) warning indicator and the brake system warning indicators are illuminated, a concern exists in the ABS module.

Safety Belt Indicator
The instrument cluster safety belt indicator illuminates if the driver safety belt is not fastened when the ignition switch is turned to the ON position. The instrument cluster receives the safety belt status hardwired from the Central Timer Module (CTM). The safety belt indicator will turn off after 60 seconds from when the engine is started, regardless of the driver safety belt status.

ABS Warning Indicator
The instrument cluster ABS system indicator is hardwired directly to the ABS module. The ABS warning indicator should prove out when the ignition switch is turned to the ON position. An open circuit, a short to battery, or an ABS failure will illuminate the ABS warning indicator.

Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) illuminates when a Diagnostic Trouble Code (DTC) is registered in the PCM if the concern affects exhaust emissions.

Powertrain Malfunction Indicator Lamp
The powertrain malfunction indicator lamp illuminates when a DTC is registered in the PCM which does not affect exhaust emissions. This lamp will also illuminate if the fail-safe cooling strategy is invoked by the PCM.

Engine Oil Pressure Warning Indicator
The engine oil pressure warning indicator is hardwired to the engine oil pressure switch. With the ignition switch in the ON position, the oil pressure indicator illuminates. After the engine is started and the oil pressure builds up, the oil pressure switch opens and switches off the oil pressure warning indicator.

Door Ajar Indicator
The door ajar indicator is Controlled By The Central Timer Module (CTM), the anti-theft alarm door locking module, and the door, liftgate and luggage compartment lid switches. The system operates by supplying a ground when a door or liftgate is opened or not fully closed, which will illuminate the indicator.

Air Bag Warning Indicator
The air bag warning indicator is controlled by the air bag module. REFER to Air Bags.

Charge System Warning Indicator
The PCM controls the charging system and the charge system warning indicator. The PCM is therefore responsible for turning the lamp off once the system is running and illuminating it under fault conditions (including stall conditions).

Shift Up Indicator
The PCM controls the shift up indicator. This indicator informs the driver when to change gear.

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.

Turn/Hazard Indicators
The Tight 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.

Configuration of the Instrument Cluster
New instrument clusters will illuminate all of the warning indicators until the instrument cluster has been configured using the scan tool. REFER to Module Communications Network (Information Bus).