Principles of Operation (How Does It Work)
The instrument cluster is a Hybrid Electronic Instrument Cluster (HEC). The instrument cluster gauges, warning indicators, and message center displays are either controlled and driven directly hardwired or the information is requested and received through the Standard Corporate Protocol (SCP). The instrument cluster has self-test diagnostics capabilities using the diagnostic tool.INSTRUMENT CLUSTER GAUGES
The instrument cluster houses three gauges:
- speedometer gauge
- fuel gauge
- engine coolant temperature gauge
Speedometer Gauge
The instrument cluster receives the vehicle speed signal from the Anti-lock Brake System (ABS) module over the SCP and displays it on the speedometer gauge. When the instrument cluster has 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 directly from the fuel sending unit. When the fuel level is low, the resistance is low. When the fuel level is high, the resistance is high.
Engine Coolant Temperature Gauge
Engine coolant temperature information is received by the instrument cluster from the Powertrain Control Module (PCM) over the SCP. Temperatures over 123°C (253°F) will cause the engine coolant temperature gauge to display hot (H). If the engine coolant temperature data is missing or invalid, the instrument cluster will move the engine coolant temperature gauge to the cold (C) position.
MESSAGE CENTER DISPLAYS
The instrument cluster has two digital message center displays. The message center displays will fully illuminate their segments for several seconds when the ignition switch is first turned on. This is simply a bezel prove-out of the message center display.
The right-side message center display indicates:
- Fuel computer/trip odometer information (e.g. FUEL ECON AVG, FUEL REMAIN, DIST TO EMPTY, AVG SPEED, TRIP A B, and E/M (English/metric)). Refer to Instrument Panel, Gauges and Warning Indicators for further details about the fuel computer/trip odometer information message display.
- Low WASHER level fluid. WASHER is displayed if the windshield washer fluid level is low, causing the switch to ground the circuit.
The left-side message center display indicates:
- AIR SUSPENSION
- CIRCLE SLOWLY
- Compass
- DOOR AJAR
- Odometer
- TRAC OFF
- TRAC ACTIVE
- TRUNK AJAR
- O/D OFF
- SPEED CONTROL
Refer to Instrument Panel, Gauges and Warning Indicators, Driver Information/Message Center for more information about the message centers.
Refer to Compass for further details of the compass.
The display panel control switch is located directly above the Electronic Automatic Temperature Control (EATC) and has a SELECT and RESET button.
Odometer
The instrument cluster receives odometer rolling count status from the Anti-lock Brake System (ABS) module and stores the mileage in Non-volatile Memory (NVM). Dashes are displayed in the odometer display and the ABS warning indicator is illuminated if the instrument cluster fails to receive the odometer rolling count status.
Traction Control
The left-side message center displays TRAC ACTIVE and TRAC OFF. The TRAC OFF display is controlled by the instrument cluster depending on the brake system configuration it receives from the ABS or ABS/traction control (ABS/TC). The TRAC ACTIVE display illuminates if the traction control is active. The instrument cluster will receive a traction control active telltale command message over the SCP from the ABS/TC. If the message is not received after the segment display prove-out, the instrument cluster turns off the TRAC ACTIVE display.
O/D Off
The overdrive off (O/D OFF) display is illuminated depending on the overdrive telltale command the instrument cluster receives from the PCM over the SCP. If the O/D switch is depressed, turning the overdrive off, the O/D OFF should be illuminated.
Speed Control
The SPEED CONTROL display illuminates when the instrument cluster receives an ON vehicle speed control high resolution set speed command from the speed control servo. The speed control servo receives its input directly from the speed control switch. If the instrument cluster fails to receive a vehicle speed high resolution set speed command, the instrument cluster defaults to the last known value. After each ignition cycle, if no command is received, the instrument cluster shall default and does not illuminate the SPEED CONTROL display.
Air Suspension
The AIR SUSPENSION display illuminates depending on the suspension system state status message the instrument cluster receives from the air suspension control module over the SCP. If the instrument cluster fails to receive a suspension system state status after the three-second prove-out duration, the instrument cluster continues to illuminate the AIR SUSPENSION display. The instrument cluster will only turn off the AIR SUSPENSION display if it receives a suspension system state status message with no failure indicated.
WARNING INDICATORS
Low Oil Pressure Indicator
NOTE: The instrument cluster will retrieve DTC B1342 if a normally open oil pressure switch is substituted for the normally closed oil pressure switch.
The low oil pressure indicator on the instrument cluster receives the oil pressure status directly from the oil pressure switch. With the ignition switch in the ON position, the low oil pressure indicator should be illuminated. After the engine is started and the oil pressure builds up, the oil pressure switch opens and turns off the low oil pressure indicator.
Brake System Warning Indicator
The brake system indicator proves out when the ignition switch is in the START position, grounding the circuit. The indicator illuminates if the brake fluid level is low or if the parking brake pedal is depressed.
Safety Belt Indicator
The instrument cluster safety belt indicator indicates if the driver safety belt is fastened when the ignition switch is turned ON. The instrument cluster receives the safety belt status from the lighting control module (LCM). The safety belt indicator will turn off after 60 seconds from when the engine was started, regardless of the driver safety belt status. An audible safety belt chime is provided by the LCM if the instrument cluster detects the driver safety belt to be unfastened.
Fail-Safe Cooling Mode Indicator
The instrument cluster carries out a three-second prove-out of the fail-safe cooling indicator when the ignition switch is turned on. After the engine is started, the PCM sends the instrument cluster a fail-safe cooling mode status. If the instrument cluster does not receive a message from the PCM, the instrument cluster assumes the OFF status and turns off the indicator.
Service Engine Soon
The SERVICE ENGINE SOON indicator is turned on with the ignition switch in the ON position. After the engine is started, the SERVICE ENGINE SOON indicator remains on for a prove-out duration of three seconds. If the PCM fails to send the instrument cluster an OFF status message, the SERVICE ENGINE SOON indicator will remain illuminated. After the prove-out duration, the SERVICE ENGINE SOON indicator is controlled directly by the PCM via the SCP to the instrument cluster.
Check Fuel Cap Indicator
The check fuel cap indicator is used to indicate major leaks in the evaporative emissions system due to a loose, missing or defective fuel cap. The fuel tank pressure is monitored by the Powertrain Control Module (PCM). If a leak is detected, the PCM signals a fault to the instrument cluster via the SCP network. Once the PCM has detected a major leak and the check fuel cap indicator is illuminated, the check fuel cap indicator will remain illuminated until the fuel cap has been secured and the vehicle has been operated for several minutes.
High Beam Indicator
The high beam indicator is controlled by the Lighting Control Module (LCM) over the SCP. When the headlamps are turned on, the LCM sends the instrument cluster a high beam indicator telltale command ON message. The instrument cluster does not prove-out the high beam indicator. If the instrument cluster does not receive a high beam indicator telltale command from the LCM, the instrument cluster does not illuminate the high beam indicator.
Air Bag Indicator
The air bag indicator is controlled by the air bag module. Refer to Air Bag Systems for further description and operation.
Charging System Indicator
The charging system indicator is directly controlled by the generator. If low voltage is detected, the charging system indicator turns on.
ABS Indicator
The ABS indicator has multiple functions. The instrument cluster proves out the ABS indicator when the ignition switch is turned ON. After the engine is started, the instrument cluster monitors the SCP messages for odometer rolling count status from the ABS module. If at any time the instrument cluster does not receive this message every two seconds, the instrument cluster illuminates the ABS indicator.
Left and Right Turn Signal Indicators
The left and right turn signal indicators on the instrument cluster are controlled by the multifunction switch and also operate together when the hazard lamps are turned on.
Instrument Cluster Installation
When a new instrument cluster installation is necessary, contact the Instrument Cluster Program at 1-800-259-9700 (U.S.) or 1-800-663-9974 (Canada).
The Passive Anti-theft System (PATS) must be reconfigured after installation of the instrument cluster. Refer to the PATS Configuration Command Index in Antitheft and Alarm Systems. PATS Configuration Command Index