Principles of Operation

PRINCIPLES OF OPERATION

When installing a new instrument cluster, it is necessary to upload the module configuration to the scan tool. Following installation of the new instrument cluster, download the module configuration from the scan tool into the new instrument cluster. Refer to Information Bus (Module Communications Network).

The following items are configurable:
- Safety belt telltale
- Safety belt telltale timeout
- Safety belt chime
- Belt minder
- Base door ajar tone (Escape, Mariner)
- Anti-theft telltale (Hybrid)
- Check cap
- Speedometer bias
- Transmission type (Escape, Mariner)
- Key reminder chime
- Default language
- ABS/TCS/IVD
- 4x4 (Hybrid)
- 4WD (Escape, Mariner)
- Oil change reminder
- Not in park chime
- Turn signal on reminders
- Park brake on
- Button press chime
- Key off dimming timer
- IFE/AFE/TFE navigation configuration (Hybrid)
- Tire pressure monitoring system (TPMS)

The instrument cluster contains a microprocessor, gauges, indicator lamps, and internal circuitry. The instrument cluster and the smart junction box (SJB) use a combination of hardwired circuitry and the controller area network (CAN) to transmit and receive information. Refer to Information Bus (Module Communications Network).

It is very important to understand:
- where the input (command) originates from.
- all the information (messages) necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- if the module which received the input controls the output of the feature, or if it sends a message over the CAN to another module.
- which module controls the output of the feature.

Each time the key is turned from off to on, the charging system indicator, the low oil pressure indicator, and the malfunction indicator lamp (MIL) prove out and remain on until the engine is started and running normally. The safety belt indicator proves out for 60 seconds or until the safety belt is fastened. The air bag indicator proves out for approximately 6-8 seconds while the following instrument cluster indicators and warning indicators prove out for approximately 3 seconds:
- Anti-lock brake system (ABS) warning indicator
- Anti-theft warning indicator
- Brake warning indicator
- Check fuel cap warning indicator (Escape, Mariner)
- Four wheel drive (4WD) indicator (Escape, Mariner)
- Low fuel level warning indicator (Escape, Mariner)
- Hazard warning indicator (Hybrid)
- Service soon warning indicator (Hybrid)
- Overtemp warning indicator
- TPMS warning indicator

Gauges

Speedometer (Escape, Mariner)
The instrument cluster receives the vehicle speed sensor (VSS) signal from the anti-lock brake system (ABS) module through the communication network. The instrument cluster monitors the VSS input from the ABS module and commands the speedometer with a corresponding movement of the pointer.

Speedometer (Hybrid)
The speedometer gauge feature informs the driver of the vehicle speed. The input to the instrument cluster is a message over the communication network from the transmission control module (TCM).

Odometer
The odometer and trip odometer are viewed through the PRNDL liquid crystal display (LCD). The odometer is tamper-resistant and accumulates and registers up to 1 million miles in US mode or 1 million kilometers in metric mode, based on rolling count data sent from the ABS module (Escape, Mariner) or the TCM (Hybrid) via the communication network. The trip odometer is resettable and accumulates and registers up to 999 kilometers or miles.

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, the resistance in the unit is low (15 ohms ± 2 ohms). When the fuel level is high, the resistance in the unit is high (160 ohms ± 4 ohms).

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 one 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 transaxle is in PARK (P) (automatic transaxle), or the parking brake applied (manual transaxle).
- 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 transaxle is put into the PARK (P) position (automatic transaxle) or when the parking brake is applied (manual transaxle). 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) or the parking brake is released, 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 missing fuel level input after 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.

Temperature Gauge (Escape, Mariner)
The powertrain control module (PCM) receives the engine coolant temperature status through hardwired circuitry to the engine coolant temperature (ECT) sensor and from 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 commands 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.

Tachometer (Escape, Mariner)
The tachometer is electrically operated and indicates the engine speed in revolutions per minute (rpm). The tachometer range is 0 to 8,000 rpm. The tachometer receives the signal over 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.

Tachometer (Hybrid)
The tachometer gauge displays the internal combustion engine revolution speed accurately and responsively and indicates when the vehicle is operating on electric power only (EV Mode). The tachometer range is 0 to 7,000 rpm. The tachometer receives the signal over the communication network from the PCM. A small segment below 0 is used to indicate electric vehicle mode when the vehicle is using electric power only.

Charge/Assist Gauge (Hybrid)
The charge/assist gauge feature is to let the driver know when the batteries in the electric drive portion of the vehicle powertrain are being charged by the internal combustion engine or regenerative braking system, or when energy from the batteries is being used to assist in moving the vehicle. The gauge movement is referenced from the battery and displays in units of kilowatts. Discharge (assist) is positive current and the gauge pointer rotates clockwise of the neutral position to a maximum of 40 kilowatts at 86 degrees. Charging is negative current and the gauge pointer rotates counterclockwise of the neutral position to a minimum of -40 kilowatts at 0 degrees. The input to the instrument cluster is over the communication network from the traction battery control module (TBCM). The charge/assist gauge feature operates only when the ignition switch is in the RUN position.

Warning Indicator Lamps

Air Bag Warning Indicator
The instrument cluster is hardwired to the restraints 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 illuminating the air bag indicator.

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 over the communication network, illuminates the ABS warning indicator.

BRAKE Warning Indicator
The parking brake warning indicator switch is hardwired to the SJB and the brake fluid level switch (part of the brake master cylinder) is hardwired to the ABS module. The instrument cluster BRAKE warning indicator uses 2 inputs. The first input is provided by the parking brake warning indicator switch and, when applied, provides a ground to the SJB which sends a signal over the communication network to illuminate 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 or base brake system concern, provides a brake signal to the instrument cluster over the communication network. The instrument cluster, upon receipt of the brake signal, 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 over the communication network. When the generator (Escape, Mariner) or DC/DC converter (Hybrid) output is insufficient to maintain the battery state of charge, the instrument cluster illuminates the charging system indicator.

Low Oil Pressure Warning Indicator (Escape, Mariner)
The low oil pressure warning indicator is hardwired to the engine oil pressure switch. When the ignition switch is in the RUN position with the engine off, the engine oil pressure switch closes and the low oil pressure warning indicator illuminates. After the engine is started and the oil pressure builds up, the engine oil pressure switch opens, removing the ground circuit to the instrument cluster and turns off the low oil pressure warning indicator.

Low Oil Pressure Warning Indicator (Hybrid)
The low oil pressure warning indicator informs the driver that a low internal combustion engine oil pressure condition has been detected. The engine oil pressure switch is a normally closed switch. When there is no oil pressure, the engine oil pressure switch is closed and the oil pressure input to the instrument cluster is grounded. The oil pressure is measured only when the internal combustion engine is running. The PCM monitors the engine actual speed and sends a message over the communication network to the instrument cluster. The instrument cluster uses the engine speed message from the PCM to determine whether the engine is running to illuminate or turn off the low oil pressure warning indicator. The low oil pressure warning indicator remains illuminated at the start of each ignition cycle until oil pressure is first sensed with the cycling on of the internal combustion engine.

Door Ajar Warning Indicator (Base Cluster)
The door ajar, the liftgate ajar, the liftgate glass ajar, and the hood ajar (Hybrid only) switches provide a ground signal to the SJB. The SJB, upon receipt of the door ajar ground data, supplies a door ajar status message to the instrument cluster over the communication network. The instrument cluster monitors the door ajar status and turns the door ajar indicator (Escape, Mariner) or a display in the message center (Hybrid) 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). 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 indicator. The passenger occupant classification sensor provides the status of the front passenger seat to the RCM over the communication network. The safety belt warning indicator may illuminate even though the driver side safety belt is buckled. This may occur if the passenger seat is occupied by an object with a significant amount of mass/weight which the occupant classification sensor classifies as an occupant. If the passenger safety belt is unbuckled, the safety belt warning indicator remains on even when the driver side safety belt is buckled. If the indicator is illuminated for this reason, this is a normal characteristic and no repair is needed.

Anti-Theft Warning Indicator
The anti-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 anti-theft warning indicator operates with a message over the communication network 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.

Low Fuel Warning Indicator
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 a pre-determined level, the instrument cluster illuminates the low fuel warning indicator (Escape, Mariner) or a display in the message center (Hybrid).

Tire Pressure Monitoring System (TPMS) Warning Indicator
Each road tire is equipped with a tire pressure sensor fastened to the inside rim of the wheel. The pressure sensor is covered by the tire and is not visible unless the tire is removed. The pressure sensor is located opposite (180 degrees) from the valve stem. The tire-mounted pressure sensors transmit signals to the SJB by using the valve stem as an antenna. These signals are sent approximately every 60 seconds when the vehicle speed exceeds 32 km/h (20 mph). The SJB compares each tire pressure sensor signal against low and high pressure limits. If the SJB determines that the tire pressure has exceeded the limit, the SJB communicates over the medium speed CAN to the instrument cluster, which then illuminates the TPMS warning indicator (Escape, Mariner) or a display in the message center (Hybrid).

Indicator Lamps

Check Fuel Cap Indicator
The check fuel cap indicator is used to indicate significant leaks in the fuel tank evaporative system due to a loose fuel cap. The fuel tank pressure is monitored by the PCM and if a leak is detected it signals a fault to the instrument cluster over the communication network. Once the PCM has detected a loose fuel cap and the indicator is illuminated, the indicator (Escape, Mariner) or a display in the message center (Hybrid) remains illuminated until the fuel cap is secured and the ignition switch is cycled one time.

High Beam Indicator
When the multifunction switch is placed in the HIGH BEAM position, the SJB sends a signal to the instrument cluster over the communication network to illuminate the high beam indicator.

O/D OFF Indicator (Escape, Mariner)
The instrument cluster receives the overdrive off signal from the PCM over the communication network. The overdrive off switch is hardwired to the PCM. When 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 a overdrive off signal to the instrument cluster and the instrument cluster illuminates the O/D OFF 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, voltage is supplied to the instrument cluster from the SJB 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 over the communication network.

Speed Control Indicator (Escape, Mariner)
The instrument cluster receives the speed control signal from the speed control module through hardwired circuitry. When the speed control is engaged, the speed control actuator provides a ground to the instrument cluster to illuminate the speed control indicator.

Four Wheel Drive (4WD) Indicator (Escape, Mariner)
The instrument cluster receives the 4WD information from the 4WD control module over the communication network. The module provides a 4WD status signal to the instrument cluster to illuminate the 4WD indicator.

PRND21 Indicator (Automatic Transaxle Only) (Escape, Mariner)
The instrument cluster PRND21 indicator is a LCD that displays the transmission range selected. Two sets of input signals are necessary for the PRND21 to operate correctly. The instrument cluster receives the transmission range signal over the communication network from the PCM and displays the appropriate range in the LCD. The brake shift interlock provides the second input signal. If the brake shift interlock input is not present, the P range is not highlighted in the LCD display.

PRNDL/Vehicle Odometer/Trip Odometer (Hybrid)
The PRNDL indicates the transmission position selection. This is done in the first line of the PRNDL/vehicle odometer/trip odometer LCD display. Each PRNDL character has a box surrounding it. The only time that the box segment is activated is when the requirements are met to display the transmission position selected. The input to the instrument cluster is a hardwired input from the redundant park relay and a message from the PCM over the communication network.

Hazard Indicator (Hybrid)
The hazard telltale informs the driver that the vehicle should be stopped or major damage to the propulsion system is probable. The input to the instrument cluster is over the communication network from the PCM, the traction battery control module (TBCM), and the TCM. The message STOP SAFELY NOW is displayed in the message center when this indicator is illuminated.

Overtemp Indicator
The overtemp indicator informs the driver of the following temperature related conditions in the vehicle. If the indicator is illuminated (not flashing), at least one of the following conditions exist:
- The internal combustion engine coolant is overheated.
- The electric motor coolant is overheated (Hybrid).
- The failsafe cooling feature is in Mode 1, which means the internal combustion engine is running a limited operating strategy in an attempt to reduce the engine temperature.

If the indicator is flashing, the failsafe cooling feature is in Mode 2, which means the internal combustion engine shuts down shortly due to an unresolved engine over temperature condition. The input to the cluster is through a communication network message from the PCM.

Service Soon Warning Indicator
The service soon warning indicator informs the driver that vehicle service is required. The input to the instrument cluster is over the communication network from the PCM, the TBCM, the TCM, and the power steering control module (PSCM).

Ready Light Indicator (Hybrid)
The ready light indicator informs the driver that the electric drivetrain is ready to operate. This indicator is required because the internal combustion engine is not operating all the time and the driver needs to receive the information that the vehicle is on. The input to the instrument cluster is a message from the PCM over the communication network.