Principles of Operation
PRINCIPLES OF OPERATIONWhen installing a new instrument cluster, it is necessary to upload the module configuration to the diagnostic tool. Following installation of the instrument cluster, download the module configuration from the diagnostic tool into the new instrument cluster. The following items are configurable:
- speedometer
- outside air temperature
- compass
- anti-lock brake system (ABS)
- anti-lock brake system/traction control (ABS/TC)
- overspeed warning chime
- reverse warning chime
- flex fuel
- overspeed trip point
- seatbelt indicator timeout
- electronic automatic temperature control (EATC)
- seatbelt chime
The instrument cluster carries out a prove-out when the ignition switch is turned from the OFF to the RUN position to verify the integrity of the warning indicators. The charging system warning indicator, the low oil pressure warning indicator and the malfunction indicator lamp (MIL) illuminate when the ignition switch is turned to the ON position, and then turns off when the engine is started and running normally. The seat belt warning indicator proves-out for 60 seconds and then turns off, or turns off when the seat belt is fastened. The following indicators prove-out for 3 seconds when the ignition switch is turned to the ON position:
- air bag
- ABS
- BRAKE
- traction control (if equipped)
- THEFT
- check fuel cap
Engine Coolant Temperature Gauge
The powertrain control module (PCM) receives the engine coolant temperature status through hardwired circuitry from 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 indication with a corresponding movement of the pointer.
Fuel Gauge
The fuel gauge receives the fuel level resistance from the fuel level sensor, part of the fuel pump module. To prevent the fuel gauge pointer from fluctuating as a result of excessive movement of fuel in the fuel tank, the instrument cluster provides a delay to the fuel gauge. If the fuel level is low, the resistance in the fuel level sensor will be 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 also illuminates the low fuel indicator when the fuel gauge shows approximately 1/8 of a tank of fuel remaining or less.
Flex-Fuel Module
The flex-fuel module is a DC-AC-DC converter. It acts as an interface between the fuel pump module and the instrument cluster fuel gauge. The flex-fuel module is located in the instrument panel, on the right side of the steering column, just behind the integrated control panel (ICP).
Speedometer/Odometer
The instrument cluster receives the vehicle speed sensor (VSS) signal from the PCM over the communication network. The instrument cluster monitors the VSS input from the PCM and commands the speedometer with a corresponding movement of the pointer.
Tachometer
The instrument cluster receives tachometer information from the PCM over the communication network.
Air Bag Warning Indicator
The instrument cluster is hardwired to the restraint control module (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 illuminating the air bag warning indicator.
Anti-Lock Brake System (ABS) Warning Indicator
The ABS warning indicator illuminates when the ABS module detects a fault in the system.
Brake System Warning Indicator
The brake system warning indicator has a dual function. It illuminates when the parking brake is applied or when a low brake fluid condition exists in the brake master cylinder reservoir. The brake system warning indicator illuminates when there is a pressure differential between the front and rear brake hydraulic systems.
Charging System Warning Indicator
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 in the ON position and the engine is OFF, the PCM sends a message 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 will send a message to the instrument cluster to turn off the charging system warning indicator.
Low Fuel Warning Indicator
The low fuel warning indicator is controlled by the instrument cluster and warns the driver when the fuel level is 1/8 of a tank or lower.
Low Oil Pressure Warning Indicator
The instrument cluster is hardwired to the oil pressure switch. When there is low (under 41 kPa [6 psi]) or no oil pressure, the oil pressure switch is open, removing the ground to the instrument cluster. When sufficient oil pressure exists, the oil pressure switch closes, providing a ground signal to the instrument cluster. The instrument cluster monitors the oil pressure ground signal and commands the low oil pressure warning indicator on or off according to engine oil pressure.
Safety Belt Warning Indicator
The RCM monitors the safety belt position through the safety belt buckle switch. When the safety belt is buckled, the RCM receives a ground signal and sends a message to the instrument cluster to turn off the safety belt warning indicator. When the safety belt is unbuckled, the ground to the RCM is removed and the RCM sends a message to the instrument cluster to illuminate the safety belt warning indicator.
Check Fuel Cap Warning Indicator
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 ground and the instrument cluster illuminates the check fuel cap warning indicator.
Traction Control Indicator
The traction control indicator flashes when the vehicle traction control is in active mode or when the anti-lock brake system (ABS) module detects a traction control system fault. The instrument cluster receives the traction control signal from the ABS module over the communication network. The instrument cluster monitors the traction control signal and when the ABS module detects a traction control concern, 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 over the communication network.
Theft Indicator
The theft indicator alerts the operator that an anti-theft system malfunction has occurred or that the anti-theft system is armed when the ignition switch is in the OFF or ACC position. The theft warning indicator operates with a message over the communication circuits from the PCM when the ignition switch is in the RUN and START positions and is controlled by the instrument cluster in the OFF and ACC positions.
High Beam Indicator
The high beam indicator illuminates when the multifunction switch is in the high beam position and sends a voltage signal to the instrument cluster.
Right and Left Turn Indicator
The right and left turn indicators illuminate when the multifunction switch is in either the turn signal position or the hazard lamps position and sends a voltage signal to the instrument cluster.
CRUISE 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 illuminate the CRUISE control indicator.