Principles of Operation

PRINCIPLES OF OPERATION

When 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:
- outside air temperature
- overspeed warning chime
- tire pressure monitoring system (TPMS) present
- compass present
- ADVTRAC present
- air suspension present
- power liftgate present
- park assist present
- running board present
- 4WD transmission present
- engineering test mode
- easy exit seat
- message center language
- gulf coast countries (GCC) speedometer calibration

The Expedition and Navigator instrument clusters are configurable, hybrid electronic clusters (HEC) that contain a microprocessor, gauges, indicator lamps, and internal circuitry. The instrument cluster is non-repairable with the exception of the warning indicator bulbs and the instrument cluster lens. The instrument cluster uses hardwired circuitry, and the controller area network (CAN) to transmit and receive data from the vehicles other modules.

It is very important to understand:
- where the input originates.
- 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 communication 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 lamps and monitored systems are operating correctly. The safety belt warning indicator proves-out for 60-seconds or until the safety belt is fastened. The malfunction indicator lamp (MIL), the CHECK GAGE, the low oil pressure warning indicator, and the charging system warning indicator illuminate continuously until the engine is started and operating normally. When the ignition switch is turned to the ON position with the engine off, the following indicators illuminate for 3 seconds:
- 4x4 HIGH indicator
- 4x4 LOW indicator
- ABS warning indicator
- air bag warning indicator (6 seconds)
- BRAKE warning indicator
- check fuel cap
- coolant temperature warning indicator
- low fuel warning indicator
- CHECK GAGE warning indicator
- low washer fluid indicator
- traction control indicator
- low tire warning indicator
- door ajar indicator
- malfunction indicator lamp (MIL)
- electronic throttle control indicator

Gauges

Integrated Circuit Display
The integrated circuit display is a vacuum fluorescent tube display that contains the odometer, trip odometer, outside air temperature and compass display on base clusters and the message center display on message center clusters. The compass module and outside air temperature sensor are hardwired to the instrument cluster. The odometer information is transmitted from the powertrain control module (PCM) through the communication network to the instrument cluster. The instrument cluster displays the appropriate message(s) upon receipt of the outside air temperature, compass heading and odometer data received.

Speedometer
The instrument cluster receives the vehicle speed sensor (VSS) signal from the PCM through the communication network. The instrument cluster monitors the VSS input from the PCM and commands the speedometer with a corresponding movement of the pointer.

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 one million kilometers in metric mode or one million miles in English mode, based upon rolling count data sent from the PCM through the communication network. The trip odometer is resettable and accumulates and registers up to 1,000 miles or 1,000 kilometers.

Fuel Gauge
The instrument cluster is hardwired to the fuel sending unit, which is a variable resistor controlled by the action of a float arm. 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). The instrument cluster monitors the input from the fuel sender and commands the fuel gauge indication according to the fuel level data.

Temperature Gauge
The 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 through the communication network. The instrument cluster monitors the engine coolant temperature data received from the PCM and commands the temperature gauge indication with a corresponding movement of the pointer.

Oil Pressure Gauge
The instrument cluster is hardwired to the oil pressure sender unit. The oil pressure sender unit consists of a diaphragm and contact points, which are normally open. When there is low or no oil pressure, the oil pressure switch remains open and removes the ground to the instrument cluster and 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 and commands the oil pressure gauge indication with a corresponding pointer movement.

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

Tachometer
The instrument cluster receives the tachometer data from the PCM through the communication network and commands the tachometer according to the data.

Indicators

Charging System Warning Indicator
The instrument cluster receives the charging system status from the PCM through the communication network. Charging system data is monitored by the instrument cluster and when the charging system voltage is low, illuminates the charging system warning indicator.

BRAKE Warning Indicator
The parking brake switch is hardwired to the instrument cluster and the brake fluid level switch is hardwired to the ABS module. The instrument cluster BRAKE warning indicator uses two inputs. The first input is provided by the parking brake switch and when applied, provides a ground to the instrument cluster turning on the BRAKE warning indicator. The second input is controlled by the ABS module. The ABS module, upon receipt of a low brake fluid level signal, ABS concern, or base brake system concern, provides a brake signal to the instrument cluster through the communication network. The instrument cluster, upon receipt of the brake signal, illuminates the BRAKE warning indicator on or off according to the monitored signal.

ABS Warning Indicator
The ABS warning indicator is used to indicate an ABS concern or deactivation of the ABS. The instrument cluster receives the ABS message from the ABS module through the communication network.

Malfunction Indicator Lamp (MIL)
The malfunction indicator lamp (MIL) is illuminated when a diagnostic trouble code (DTC) is detected by the PCM. The instrument cluster receives the MIL data from the PCM through 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 DTC is logged and the RCM provides a ground path to the instrument cluster turning on the air bag indicator.

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 signal and provides a ground signal to the instrument cluster to turn off the safety belt warning indicator. When the safety belt is unbuckled, the ground to the instrument cluster is removed and the safety belt indicator is turned on.

Low Fuel Warning Indicator (if equipped)
The low fuel warning indicator is controlled by the instrument cluster and uses hardwired fuel level data from the fuel pump module. When the fuel level drops below approximately one-sixteenth of a tank, the instrument cluster illuminates the low fuel warning indicator.

Coolant Temperature Warning Indicator (if equipped)
The PCM receives the engine coolant temperature status through hardwired circuitry from the ECT sensor. Engine coolant temperature status is subsequently transmitted to the instrument cluster from the PCM through the communication network. The instrument cluster monitors the engine coolant temperature data received from the PCM and commands the coolant temperature warning indicator on when coolant temperature reaches 118°-121°C (244°-250°F).

Low Oil Pressure Warning Indicator (if equipped)
The instrument cluster is hardwired to the oil pressure switch. The oil pressure switch unit consists of a diaphragm and contact points, which are normally open. When there is low (under 6 psi [41 kPa]) or no oil pressure, the oil pressure switch remains 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 microprocessor monitors the oil pressure ground signal and commands the low oil pressure warning indicator on or off according to engine oil pressure.

Door Ajar Indicator
The door ajar switches provide a ground signal to the vehicle security module. 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.

Traction Control Indicator
The traction control indicator flashes when the vehicle traction control is in active mode or is being controlled by the ABS module. The instrument cluster receives the traction control signal from the ABS module through the communication network. The instrument cluster monitors the traction control signal and when the ABS module detects a traction control concern, the instrument cluster illuminates the traction control 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.

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.

Speed Control Indicator
The instrument cluster receives the speed control signal from the PCM through the communication network. When the speed control is engaged, the PCM sends a message over the communication network to the instrument cluster which illuminates the speed control indicator.

CHECK GAGE Warning Indicator - Expedition
The CHECK GAGE warning indicator illuminates when either of the following conditions exist:
- if the engine oil pressure drops below approximately 42 kPa (6 psi)
- if the engine temperature exceeds approximately 118°C (244°F)
- if the fuel gauge is at or near empty

Low Washer Fluid Indicator - Expedition
The instrument cluster is hardwired to the low washer fluid switch. The low washer fluid switch closes when the washer fluid level is approximately 1/3 full, providing a ground to the instrument cluster and turning on the low washer fluid indicator. When the washer fluid is above the low level, the low washer fluid switch opens, removing the ground to the instrument cluster, and the low washer fluid indicator turns off.

Check Tires Indicator
The instrument cluster receives the check tires signal from the vehicle security module through the communication network. The vehicle security module compares tire pressure against low and high pressure limits. If the vehicle security module determines that the tire pressure has exceeded the limit, a message is sent to the instrument cluster requesting that the low tire warning indicator be turned on.

Overdrive Off Indicator
The instrument cluster receives the overdrive off signal from the PCM through the communication network. The overdrive off switch is hardwired to the PCM. When the transmission overdrive is selected off, the overdrive off switch provides a ground signal to the PCM. The PCM upon receipt of the overdrive off ground signal, provides an overdrive off signal to the instrument cluster and the instrument cluster illuminates the overdrive off 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 and illuminates the appropriate indicator.

Electronic Throttle Control
The instrument cluster receives the electronic throttle control status from the PCM over the communication network. When a system concern is detected, the PCM sends the instrument cluster a command signal to illuminate the electronic throttle control indicator.

Check Fuel Cap Warning Indicator
The check fuel cap indicator is used to indicate significant leaks in the fuel tank evaporative emission system due to a loose fuel cap or other fuel evaporative emission system concern. The fuel tank pressure is monitored by the PCM and, once a leak is detected, the PCM signals a fault to the instrument cluster through the communication network. Once the PCM has detected a loose fuel cap and the check fuel cap indicator is illuminated, the check fuel cap indicator remains illuminated until the fuel cap is secured and the vehicle has been running for several minutes or the ignition has been cycled once.