Principles of Operation

INSTRUMENT CLUSTER

Base Instrument Cluster, Part 1:

Base Instrument Cluster, Part 2:

Optional Instrument Cluster, Part 1:

Optional Instrument Cluster, Part 2:

SVT Oil Pressure And Oil Temperature Cluster, Part 1:

SVT Oil Pressure And Oil Temperature Cluster, Part 2:

The base and optional instrument clusters both contains gauges, indicator lamps, and warning lamps that are designed to provide the driver with system status and to alert the driver that certain conditions exist in the vehicle. Gauges provide information to the driver indicating the status of systems. The systems that use gauges include vehicle speed, fuel level, engine coolant temperature, and engine rpm. Indicator lamps provide information to the driver of conditions that exist in the vehicle. The indicator lamps include the turn signal, CHECK FUEL CAP, traction control, and speed control. Warning indicator lamps provide information to the driver of conditions that could potentially alter vehicle performance. Examples of the warning indicators include the ABS, BRAKE, safety belt, and low oil pressure.

PRINCIPLES OF OPERATION

NOTE: Upon installation, a new instrument cluster must be reconfigured.

The instrument cluster is a hybrid electronic cluster (HEC) with two basic configurations, the base cluster and the optional instrument cluster. In addition to the two basic configurations, the SVT uses a modified optional cluster in combination with a separate oil pressure and oil temperature cluster. The base instrument cluster, optional instrument cluster and the oil pressure and oil temperature cluster receive an output information utilizing both hardwired circuitry and the standard corporate protocol (SCP) or the controller area network (CAN) communication network (2.3L only).

An additional feature of the SVT instrument cluster and oil pressure and oil temperature cluster configuration is the use of an electro-luminescent backlighting strategy. The electro-luminescent backlighting utilizes switched DC to high AC voltage circuitry. The oil pressure and oil temperature cluster converts 12 V DC into AC voltage that is variable up to 180 V AC through the dimmer switch control.

CAUTION: The SVT instrument cluster utilizes high AC voltage for the electro-luminescent backlighting system in both the instrument cluster and oil pressure and oil temperature cluster. Care must be exercised when making measurements to the instrument cluster circuits.

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 or CAN 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 placed in the ON position with the engine off, the following warning indicators will prove out:
- check transmission indicator
- malfunction indicator lamp (MIL) indicator
- oil pressure indicator
- safety belt warning indicator
- door ajar warning indicator

The following indicators are also displayed during prove-out but are not controlled by the instrument cluster:
- anti-lock brake system (ABS) warning indicator
- O/D OFF indicator
- air bag warning indicator
- brake warning indicator
- charging system warning indicator
- shift up indicator
- low fuel warning indicator
- traction control indicator
- CHECK FUEL CAP indicator
- speed control indicator

Tachometer
Engine speed data is transmitted to the instrument cluster from the powertrain control module (PCM) over the SCP or CAN communication network.

Speedometer
The instrument cluster receives the vehicle speed signal from the PCM over the SCP or CAN communication 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 or CAN communication network. If the engine coolant temperature information is missing or invalid, the temperature gauge will indicate below the cold (C) position.

Oil Pressure Gauge (SVT Only)
There are two inputs required for correct oil pressure gauge operation. The first input to the instrument cluster is through hardwired circuitry to the oil pressure switch. The second input is the engine rpm, which comes from the PCM through the SCP or CAN communication network. When there is low oil pressure, the oil pressure switch opens and the instrument cluster micro-processor commands the oil pressure gauge into the low region of the gauge. When oil pressure is present the oil pressure switch closes, providing a ground to the instrument cluster and the instrument cluster micro-processor commands the oil pressure gauge into the appropriate region. The rpm signal allows the instrument cluster micro-processor to vary the needle position based upon the speed of the vehicle.

Oil Temperature Gauge (SVT Only)
The engine oil temperature signal is transmitted to the instrument cluster from the PCM through the SCP or CAN communication network. The instrument cluster micro-processor upon receipt of the oil temperature data, commands the oil temperature gauge indication to the appropriate needle position.

Odometer/Trip Odometer
The odometer and trip odometer are displayed in the integrated circuit LCD display. The instrument cluster records the total mileage of the vehicle, using information received from the PCM and electronically displays this information in the LCD. If this information is not received, the LCD will display all dashes.

Traction Control Indicator (Except 2.3L)
The instrument cluster provides a traction control indication to inform the driver when the traction control is active. The traction control signal comes from the anti-lock brake system (ABS) module and is hardwired to the instrument cluster. When the traction control is in the active mode the ABS module provides a ground signal to the instrument cluster and the traction control indicator is turned on.

Check Fuel Cap Indicator
The check fuel cap indicator is used to indicate significant leaks in the fuel tank evaporative system due to a loose fuel cap. Fuel tank pressure is monitored by the PCM and once a leak is detected, the PCM signals a fault to the instrument cluster over the SCP or CAN communication network. Once the PCM has detected a loose fuel cap and the check fuel cap indicator is illuminated, the check fuel cap indicator will remain illuminated until the fuel cap is secured and the vehicle has been running for several minutes or the ignition has been cycled once. Refer to Computers and Control Systems.

Speed Control Indicator
The speed control indicator is hardwired to the speed control module. When the speed control has been engaged the speed control module provides a ground to the instrument cluster to turn on the speed control indicator.

Low Fuel Warning Indicator
The instrument cluster utilizes fuel level data supplied by the hardwired fuel pump module to control the low fuel warning indicator, which illuminates when the fuel drops to a pre-determined level.

Brake Warning Indicator
The brake warning indicator is controlled by multiple inputs and illuminates under multiple conditions. The instrument cluster is hardwired to the parking brake switch and illuminates when the parking brake is set. The instrument cluster is also hardwired to the brake fluid level switch and illuminates when the brake fluid level is low. Finally, the instrument cluster is hardwired to the ABS module, which commands the brake warning indicator on when a base brake system concern or ABS concern exists.

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 RUN position. The instrument cluster receives the safety belt status hardwired from the generic electronic module (GEM). 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 warning indicator is hardwired directly to the ABS module. When an ABS failure, open control circuit, or a control circuit short to battery occurs, the instrument cluster turns on ABS warning indicator.

Malfunction Indicator Lamp (MIL)
The instrument cluster receives the MIL status from the PCM over the SCP or CAN communication network. The PCM sends a command to the instrument cluster when a diagnostic trouble code (DTC) is registered in the PCM if the concern affects exhaust emissions to turn on the MIL indicator.

Powertrain Malfunction Indicator Lamp (Except 2.3L)
The instrument cluster receives the powertrain malfunction status from the PCM over the SCP or CAN communication network. 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.

O/D OFF Indicator
The instrument cluster receives the O/D OFF indicator status from the PCM over the SCP or CAN communication network. When the overdrive function has been selected off, the PCM sends a command to the instrument cluster to turn on the O/D OFF indicator. On the 2.3L only, when a powertrain concern exists, the O/D OFF indicator flashes green and illuminates amber when overdrive is selected off.

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 RUN position with the engine off, the oil pressure switch opens and the oil pressure warning indicator illuminates. After the engine is started and the oil pressure builds up, the oil pressure switch closes, grounding the control circuit to the instrument cluster and turns off the oil pressure warning indicator.

Door Ajar Warning Indicator
The door ajar warning indicator is controlled by the GEM, anti-theft module, door, liftgate and luggage compartment lid switches. The instrument cluster receives a ground signal when a door or liftgate is opened or not fully closed and turns on the door ajar warning indicator.

Air Bag Warning Indicator
The instrument cluster air bag warning indicator is hardwired to the restraint control module. An open circuit, a short to battery or an air bag restraint system concern will illuminate the air bag warning indicator.

Charging System Warning Indicator
The instrument cluster receives the charging system status from the PCM over the SCP or CAN communication network. The PCM controls the charging system and the charging 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 instrument cluster receives the shift up status from the PCM. When the engine conditions are within ranges, the PCM transmits a command to the instrument cluster over the SCP or CAN communication network to turn on the shift up indicator.

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

Turn/Hazard Indicators
The right and left turn indicators are hardwired to the instrument cluster and 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 diagnostic tool.