Instrument Cluster

INSTRUMENT CLUSTER

There are 4 instrument cluster configurations available:
- base workhorse cluster
- family carrier
- image and power
- luxury message center cluster

The base workhorse, family carrier, and image and power clusters all contain indicator and warning lamps, speedometer, fuel gauge, oil pressure gauge, temperature gauge, voltage gauge, and an integrated circuit display. The luxury cluster contains a message center in place of the integrated circuit display with an expanded message list. The instrument cluster gauges, indicator lamps, warning lamps, and the integrated circuit display/message center 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. Examples of 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. Examples of the indicator lamps include the turn signal, 4x4 HIGH/LOW, high beam, 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.

Vehicles that are not equipped with a message center contain an integrated circuit display located in the lower RH corner of the instrument cluster. The integrated circuit is a two line liquid crystal display (LCD) that provides the odometer, trip odometer, outside air temperature (if equipped), compass display (if equipped) and the driver information messages.

PRINCIPLES OF OPERATION

The instrument cluster is a configurable, hybrid electronic cluster (HEC) that contains a microprocessor, gauges, indicator lamps, and internal circuitry. The instrument cluster is non-repairable with the exception of the instrument cluster lens and indicator bulbs. The instrument cluster uses hardwired circuitry, the controller area network (CAN) and the universal asynchronous receiver transmitter (UART)-based protocol (UBP) communication networks. Communication using the CAN transmits and receives data between the instrument cluster and the powertrain control module (PCM), and the antilock brake system (ABS) module. Communication using the UBP network uses data transmitted and received by the instrument cluster, and the electronic automatic temperature control (EATC), vehicle security module, and the driver seat module. The restraint control module (RCM) and the parking aid module communication is on the international standards organization (ISO) network. For additional information regarding the CAN, UBP and ISO communication networks, refer to Information Bus (Module Communications Network).

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.
- whether the module which received the input controls the output of the feature, or whether it outputs a message over the communication network to another module.
- which module controls the output of the feature.

Instrument Cluster Module Configuration
When installing a new instrument cluster, the instrument cluster must be configured. The instrument cluster is a configurable, hybrid electronic cluster (HEC) that contains a microprocessor, gauges, indicator lamps, and internal circuitry. The following items must be configured when installing a new instrument cluster:
- vehicle security module
- outside air temperature
- outside air temperature settings (°C/°F)
- compass
- climate control (manual or electronic)
- belt minder
- speedometer
- overspeed warning

The instrument cluster carries out a display prove-out to verify that the warning/indicator lamps and monitored systems are operating correctly. When the ignition switch is turned to the ON position, the charging system warning indicator and the malfunction indicator lamp (MIL) illuminate until the engine starts. The door ajar warning indicator illuminates only with the key in the START/RUN position and one or more doors are open, turning off only when the doors are closed. When the ignition switch is turned to the ON position with the engine off, the following indicators will illuminate for approximately 3 seconds with the exception of the air bag warning indicator, which illuminates for approximately 6 seconds:
- ABS warning indicator
- BRAKE warning indicator
- 4x4 high indicator
- LOW RANGE indicator
- electronic throttle control (ETC)

Integrated Circuit Display
The driver information messages are transmitted to the instrument cluster over the communication network. The compass module and outside air temperature sensor are hardwired to the instrument cluster. The odometer and trip odometer information is transmitted from the PCM through the communication network to the instrument cluster.

In addition to the compass, outside air temperature and odometer/trip odometer, the integrated circuit provides the driver with information using a text-based format. The CHECK GAUGES display illuminates when there is low oil pressure, high engine coolant temperature or when the vehicle has entered into the fail-safe cooling mode.

Gauges

Speedometer
The instrument cluster receives the vehicle speed sensor (VSS) signal which originates in the ABS module and is transmitted to the PCM over the communication network. The PCM monitors the VSS input and sends it to the instrument cluster over the communication network. With the VSS input, the instrument cluster provides the speedometer with a corresponding pointer movement.

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

Odometer/Trip Odometer
The odometer and trip odometer are viewed through the message center in the integrated circuit display on message center clusters or in the integrated circuit display on base clusters. The odometer is tamper-resistant and accumulates and registers up to 999,999 kilometers or miles, based upon rolling count data sent from the PCM over the communication network. The trip odometer accumulates and registers up to 999.9 kilometers or miles and can be reset.

Fuel Gauge
The instrument cluster receives the fuel level 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. When the fuel level is low, resistance in the unit is low (15 ohms ± 1 ohm). When the fuel level is high, the resistance is high (160 ohms ± 2 ohms).

Temperature Gauge
The PCM receives the engine coolant temperature status through hardwired circuitry to the cylinder head temperature (CHT) sensor. The instrument cluster receives the engine coolant temperature data from the PCM over the communication network. The instrument cluster monitors the engine coolant temperature data received from the PCM and provides the temperature gauge indication with a corresponding movement of the pointer. If the instrument cluster receives no signal the temperature gauge defaults to the COLD position.

Oil Pressure Gauge
The instrument cluster is hardwired to the engine oil pressure switch. The engine oil pressure switch consists of a diaphragm and contact points, which are normally open. When there is low or no oil pressure, the engine oil pressure switch remains open and removes the ground to the instrument cluster. When sufficient oil pressure exists, the engine oil pressure switch closes, providing a ground signal to the instrument cluster. The instrument cluster monitors the oil pressure and provides the oil pressure gauge indication with a corresponding pointer movement.

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

Warning Indicator Lamps

Air Bag Warning Indicator
The air bag warning indicator is used to provide a status of the supplemental restraint system. The instrument cluster is hardwired to the RCM. If an air bag system concern is detected, a diagnostic trouble code (DTC) is logged and the RCM provides a ground path to the instrument cluster turning on the air bag warning indicator.

Anti-Lock Brake System (ABS) Warning Indicator
The ABS warning indicator is used to indicate an ABS concern or deactivation of the ABS. The instrument cluster, upon receipt of the ABS message from the ABS module through the communication network, turns on the ABS warning indicator.

BRAKE Warning Indicator
The instrument cluster BRAKE warning indicator illuminates when:
- the parking brake is applied.
- there is low brake fluid level.
- the brake fluid level switch is disconnected.
- an electronic brake distribution (EBD) concern exists.
- a loss of communication between the ABS module and the instrument cluster occurs.

The parking brake switch and the brake fluid level switch are hardwired to the instrument cluster. The parking brake switch provides a ground to the instrument cluster when the parking brake switch is applied. The brake fluid level switch provides a ground to the instrument cluster when the brake fluid level is low or an open circuit or if the switch is disconnected. The base brake system and the EBD system is monitored by the ABS module. When a concern exists with the base brake system or EBD, the ABS module provides a signal to the instrument cluster through the communication network. The instrument cluster turns the BRAKE warning indicator on or off, according to the monitored data.

Charging System Warning Indicator
The instrument cluster receives the charge signal from the PCM through the communication network. When the generator output is insufficient to maintain the battery state of charge the instrument cluster illuminates the charging system indicator.

Door Ajar Warning Indicator
The door ajar switches provide a ground signal to the instrument cluster on vehicles not equipped with the remote keyless entry (RKE) system and to the vehicle security module on vehicles equipped with the RKE system. The vehicle security module, upon receipt of the door ajar ground data, supplies a door ajar status message to the instrument cluster through the communication network. The instrument cluster monitors the door ajar status and commands the door ajar indicator on or off according to the door ajar status message.

Safety Belt Warning Indicator
The RCM monitors the safety belt position through the safety belt switch (part of the buckle). The RCM communicates the status of the safety belt switch to the instrument cluster through hardwired circuitry. When the safety belt is unbuckled, the safety belt switch closes to ground, signaling the RCM that the safety belt is unbuckled. The RCM provides a ground signal to the instrument cluster to turn on the safety belt warning indicator. When the safety belt is buckled, the safety belt switch opens to the RCM and the RCM in turn removes the ground to the instrument cluster to turn off the safety belt warning indicator.

Indicator Lamps

Electronic Throttle Control (ETC) Indicator
The PCM monitors the ETC and provides the instrument cluster with the ETC status over the communication network. When a system concern is detected, the PCM provides the instrument cluster with a signal commanding the instrument cluster to turn on the ETC indicator.

High Beam Indicator
The instrument cluster provides a ground for the high beam indicator. When the high beams are turned on, the multifunction switch provides a power signal to the instrument cluster through hardwired circuitry and illuminates the high beam indicator.

RH and LH Turn Indicators
The instrument cluster provides a ground for the RH and LH turn indicators. When the multifunction switch is in the RH or LH turn position, power is supplied to the instrument cluster through hardwired circuitry and the RH or LH turn indicators flash on and off.

Malfunction Indicator Lamp (MIL)
The MIL is illuminated when a DTC is detected by the PCM. The instrument cluster receives the MIL data from the PCM through the communication network.

Speed Control Indicator
The instrument cluster receives the speed control data from the PCM through the communication network. When the speed control is engaged, the PCM provides a signal to the instrument cluster to turn on the speed control indicator.

4x4 HIGH and 4x4 LOW Indicators
The instrument cluster receives the 4x4 HIGH and 4x4 LOW information from the PCM through the communication network. When either 4x4 high or 4x4 low are selected, the PCM provides a 4x4 status signal to the instrument cluster to turn on the appropriate indicator.