Principles of Operation
PRINCIPLES OF OPERATIONWhen installing a new instrument cluster, it is necessary to upload the module configuration information to the scan tool. Following installation of the instrument cluster, download the module configuration information from the scan tool into the new instrument cluster. Refer to Information Bus (Module Communications Network).
The following items are configurable:
- All wheel drive (AWD)
- Compass
- Anti-lock brake system/traction control/stability assist (ABS/TC)
- Low coolant warning indicator
- Speedometer bias
- Climate control type
- Oil life threshold
- Default language
The instrument cluster contains an analog speedometer, tachometer, fuel gauge, and engine coolant temperature gauge. The instrument cluster receives the information over the controller area network (CAN) circuits. 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, the low oil pressure, and the malfunction indicator lamps (MIL) illuminate until the engine is started and operating normally.
Each time the ignition switch is turned from off to on, the following instrument cluster warning indicators prove out:
- Air bag (6 seconds)
- ABS (3 seconds)
- Brake (3 seconds)
- Low coolant level (3 seconds)
- Low fuel (3 seconds)
- Low washer fluid (3 seconds)
- Safety belt (60 seconds or until the safety belt is buckled)
- Traction control (3 seconds)
- Anti-theft (3 seconds)
- Wrench indicator (3 seconds)
- Check fuel cap (3 seconds)
Instrument Cluster Gauges
Engine Coolant Temperature Gauge
The powertrain control module (PCM) receives the engine coolant temperature status through hardwired circuitry to the engine coolant temperature (ECT) 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 commands the engine coolant temperature gauge pointer.
Fuel Gauge
The fuel gauge informs the driver of the amount of fuel remaining in the tank. The fuel tank is a saddle tank design with variable resistance senders, driven by floats, that provide resistances related to fuel height, in each side of the tank, to the instrument cluster. The fuel level input is provided independently from each fuel level sensor. The fuel level sensors provide variable resistance between 15 ohms ± 2 ohms (empty tank) and 160 ohms ± 4 ohms (full tank). If the fuel level is low, the resistance in the fuel level sensor is low, causing the gauge to indicate empty (E). When the fuel level is high, the resistance in the fuel level sensor is high, and the gauge indicates full (F).
The instrument cluster uses 4 different operating modes to calculate the fuel level:
- Anti-slosh (default mode)
- Key OFF fueling
- Key ON fueling
- Recovery
After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.
The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from empty (E) to full (F).
The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:
- The key must be in the OFF position throughout the entire refueling of the vehicle.
- At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
- The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms.
If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:
- The transmission is in PARK (P).
- The key is in the RUN position.
- At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
In key ON fueling mode, a 30-second timer activates after the transmission is put into the PARK (P) position. When the 30 second time has elapsed and at least 15% of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of PARK (P), the fuel gauge strategy reverts to the anti-slosh mode. The key ON fueling mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.
Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level input during a refueling event. Missing fuel level inputs result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:
- The instrument cluster is in the anti-slosh (default) mode.
- The actual fuel level in the tank is greater than what is being displayed by the fuel gauge.
Speedometer
The instrument cluster receives the vehicle speed data from the ABS module over the communication network and commands the speedometer pointer appropriately.
Tachometer
The instrument cluster receives the tachometer data from the PCM over the communication network and commands the tachometer pointer between 0 and 7,000 rpm, according to the data.
Indicators
Air Bag
The air bag warning indicator is used to provide a status of the supplemental restraint system (SRS). The instrument cluster receives a message from the restraints control module (RCM) over the communication network. If an air bag system concern is detected, a diagnostic trouble code (DTC) is logged and the RCM sends a message to the instrument cluster to turn on the air bag warning indicator.
Anti-Lock Brake System (ABS)
The ABS warning indicator informs the driver of a malfunction in the ABS system. Inputs are provided by the ABS module over the communication network.
Brake System
The brake warning indicator alerts the driver if any of the following brake system conditions are present: the parking brake is set, the brake fluid level is low, the ABS module has detected a base brake system failure, there has been a loss of communication between the instrument cluster and the smart junction box (SJB), and there has been a loss of communication between the instrument cluster and the ABS module.
Charging System
The PCM constantly monitors the generator regulator output. When the PCM detects a continuous high or low output signal, or when the ignition switch is on and the engine is off, the PCM sends a message over the communication network to the instrument cluster to illuminate the charging system warning indicator. When the ignition switch is in the ON position, with the engine running, and the PCM determines that the set point for the regulator has been met, the PCM sends a message to the instrument cluster to turn off the charging system warning indicator.
Low Fuel
The low fuel warning indicator is controlled by the instrument cluster and warns the driver when the fuel level is approximately 1/8 of a tank or lower.
Low Oil Pressure
The oil pressure switch is hardwired to the SJB. When there is low or no oil pressure, the SJB sends a message over the communication network to the instrument cluster to illuminate the low oil pressure warning indicator according to engine oil pressure.
Safety Belt
The safety belt warning indicator informs the driver that the safety belt and/or the front passenger's safety belt is unbuckled. The first 65 seconds after the ignition switch transitions from OFF or ACC to RUN or START, the safety belt warning indicator and the associated chime are used as a reminder to the driver that the front row safety belts are not buckled. In this first 65 seconds the indicator illuminates when the driver and/or front passenger safety belt is unbuckled (with a person in the seat) and turns off whenever the safety belt(s) in the occupied front row seat(s) is buckled. The indicator re-illuminates if a safety belt is unbuckled after both are buckled and the 65 seconds has not yet expired. After 65 seconds, the indicator turns off regardless of the front row safety belts status.
Check Fuel Cap
The PCM monitors pressure in the fuel evaporative system and detects massive or critical losses of pressure. When a critical loss of pressure in the fuel evaporative system is detected, the PCM provides a message over the communication network and the instrument cluster illuminates the check fuel cap warning indicator.
Traction Control
The traction control indicator flashes when the traction control is in active mode and is being controlled by the ABS module or the all wheel drive control module. The instrument cluster receives the traction control signal from the ABS module or the differential electronic module (DEM) (all wheel drive control module) through the communication network. The instrument cluster monitors the traction control and the all wheel drive signal, and when the ABS module or the all wheel drive module detects a concern, the instrument cluster illuminates the traction control indicator.
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.
Anti-Theft
The anti-theft indicator provides an indication in the ignition switch OFF position that there is an anti-theft system in the vehicle. When the ignition switch is in the ON position, the anti-theft indicator indicates whether or not a concern is detected with the anti-theft system by illuminating the indicator for 60 seconds (solid or flashing) and then flashing a fault code 10 times. The indicator is controlled by the PCM via hardwired circuits.
Door Ajar
The door ajar indicator informs the driver that one or more doors, the decklid, or the liftgate is open while the ignition switch is in RUN position. When a door, decklid, or the liftgate is ajar, the SJB sends a message to the instrument cluster to turn on the door ajar indicator.
Low Coolant Level
The low coolant warning indicator, located in the degas bottle, illuminates when a low coolant level is detected. The SJB receives the information from the low coolant level switch and sends the instrument cluster a message over the communication network to turn on the low coolant warning indicator.
Low Washer Fluid
The low washer fluid indicator, located in the windshield washer fluid reservoir, illuminates when a low washer fluid level is detected. The SJB receives the information from the low washer fluid level switch and sends the instrument cluster a message over the communication network to turn on the low washer fluid indicator.
Wrench Indicator
The instrument cluster receives the wrench warning indicator status from the powertrain control module (PCM) for the electronic throttle control (ETC) concerns and the transmission control module (TCM) for transaxle concerns over the communication network. When a system concern is detected, the PCM or the TCM sets a DTC and sends the instrument cluster a command signal to illuminate the wrench warning indicator.
Speed Control
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.
High Beam
When the high beams are turned on, the SJB sends a signal to the instrument cluster through the communication network to illuminate the high beam indicator.
Turn Signal
The SJB sends a message to the instrument cluster over the communication network when the multifunction switch is in the RH and LH TURN position. When the multifunction switch is in the RH or LH TURN position, the instrument cluster flashes the RH or LH turn indicators.