Principles of Operation

PRINCIPLES OF OPERATION

NOTE:
- The instrument cluster, front electronic module (FEM), and the rear electronic module (REM) must be configured upon installation. Refer to Information Bus (Module Communications Network).
- The diagnostic tool may display ICM for the instrument cluster.
- For any concerns with the restraint control module (RCM), refer to Air Bag Systems.
- The instrument cluster is not repairable at the dealership with the exception of the instrument cluster lens. Do not disassemble the instrument cluster.

The instrument cluster is a hybrid electronic instrument cluster (HEC). The vehicle electronic functions are divided into zones (front and rear). The instrument cluster, FEM, and REM use the communication network to transmit and receive information. It is very important to understand:
- where the input (command) originates from.
- all information (messages) necessary in order for a feature to operate.
- which module(s) receive(s) the input or command message.
- whether the module which received the input (message) controls the output of the feature, or whether it outputs a message over the communication network to another module.
- which module controls the output of the feature.

The instrument cluster communicates with the FEM, REM, anti-lock brake system (ABS), powertrain control module (PCM), and the RCM over the communication network to control the gauges, indicators, and chimes.

The instrument cluster carries out a display prove-out to verify the integrity of the cluster controlled indicators. When the key is in the ON position with the engine off, the following warning indicators will prove out:
- BRAKE warning indicator
- anti-lock brake system (ABS) warning indicator
- engine over-temperature warning indicator
- traction control
- low fuel indicator
- low washer fluid warning indicator
- CHECK FUEL CAP indicator

There are 3 indicators that also maintain a prove-out but are controlled by other modules. The air bag warning indicator prove-out is controlled by the RCM, the check engine indicator is controlled by the PCM and the charging system warning indicator is controlled by the PCM.

Integrated Circuit Display
The integrated circuit display is a fluorescent vacuum tube display that maintains 3 separate functions housed in a single display area: the warning center display, the trip A/B and odometer display, and the PRNDL display.

Warning Center Display
The warning center display alerts the driver of a lamp outage condition and is contained in the integrated display. The FEM and REM both control the exterior illumination. When an exterior lamp is inoperative, the FEM or REM notify the instrument cluster over the communication network and the instrument cluster illuminates the warning center message LAMP OUT. The warning center message remains on until the condition is corrected. Once the condition is corrected, the warning center returns to the trip odometer display.

Trip A/B And Odometer Displays
The vehicle speed signal (VSS) from all 4 wheels is hardwired directly to the ABS. The vehicle speed rolling count status is then sent to the instrument cluster by the ABS module over the communication network.

PRNDL Display
The digital transmission range (TR) sensor is hardwired directly to the PCM. The status of the gear selection is sent to the instrument cluster from the PCM over the communication network.

Gauges

Fuel Gauge
The fuel gauge system has a saddle-type fuel tank with 2 integrated fuel senders: the fuel delivery module and the jet pump module. The fuel delivery module is located in the right side of the fuel tank and the jet pump module is located in the left side of the fuel tank. The fuel level status is sent directly to the REM, which is hardwired to the fuel senders.

The REM sends the fuel data to the instrument cluster via the communication network. Normal operating range of the fuel delivery module is from 16 ± 2 ohms at empty (E) to 155 ± 4 ohms at full (F). The normal operating range of the jet pump module is from 19 ± 2 ohms at empty (E) to 160 ± 2 ohms at full (F). If the jet pump module is open, the fuel gauge defaults to the fuel delivery module sender value only and the fuel gauge indicates E to 1/2 tank depending on the fuel level on the fuel driver module side of the tank. If the fuel delivery module is open, the fuel gauge defaults to the empty (E) position.

Speedometer Gauge
The instrument cluster uses a vehicle speed signal from the ABS module to control the movement of the speedometer pointer. Vehicle speed information is received by the ABS module from all 4 wheel speed sensors, which is then sent to the instrument cluster by the ABS module over the communication network. Tachometer Gauge The instrument cluster uses crankshaft speed information sent to the PCM from the crankshaft position sensor (CKP) to control the movement of the tachometer pointer. The CKP sensor is hardwired directly to the PCM, which provides the crankshaft position sensor status to the instrument cluster over the communication network.

Tachometer Gauge
The instrument cluster uses crankshaft speed information sent to the PCM from the crankshaft position sensor (CKP) to control the movement of the tachometer pointer. The CKP sensor is hardwired directly to the PCM, which provides the crankshaft position sensor status to the instrument cluster over the communication network.

Temperature Gauge
The cylinder head temperature sending unit is hardwired directly to the PCM. The status of the cylinder head temperature is sent from the PCM over the communication network to the instrument cluster. The normal operating temperature range is 60°C (140°F) to 120°C (248°F). Redline starts at 121°C (249.8°F).

Warning Indicator Lamps

Air Bag Warning Indicator
The supplemental restraint system is monitored and controlled by the RCM. The status of the supplemental restraint system is sent from the RCM to the instrument cluster through hardwired circuitry. The AIR BAG warning indicator is illuminated when the RCM removes the ground signal to the instrument cluster.

Anti-Lock Brake System (ABS) Warning Indicator
The ABS is monitored by the ABS module, which sends the status signal to the instrument cluster over the communication network. The instrument cluster uses this input to determine whether or not there is a fault with the ABS and turns on the ABS warning indicator according to the input.

Brake Warning Indication
The BRAKE warning indicator illuminates when the parking brake is engaged, the brake fluid level is low, or a base brake system concern exists. These functions are controlled by the parking brake switch, the brake fluid level switch, and the ABS module. The FEM monitors the parking brake switch and sends a message to the instrument cluster when the parking brake is engaged. The brake fluid level switch is hardwired directly to the FEM. When the brake fluid is low, the FEM sends a signal to the instrument cluster over the communication network to turn on the brake warning indicator. The ABS module monitors the base brake system and sends a message to the instrument cluster to turn on the BRAKE warning indicator if a concern exists.

Charging System Warning Indicator
The charging system controls are accomplished through the PCM, which monitors the output of the generator through hardwired circuitry. The status of the charging system is then relayed from the PCM to the instrument cluster over the communication network.

Door Ajar Warning Indicator
The instrument cluster uses door ajar status provided by the FEM over the communication network. The door switches are directly hardwired to the FEM, which uses the multiple inputs from each door switch to determine whether the doors are in the opened or closed position and relays the status to the instrument cluster to turn on or off the door ajar indicator.

Engine Over-Temperature Warning Indicator
The engine over-temperature status is determined by the cylinder head temperature sender unit, which is hardwired directly to the PCM. The status of the cylinder head temperature is sent from the PCM over the communication network to the instrument cluster.

Low Fuel Warning Indicator
There are 2 fuel tank senders, which are hardwired directly to the REM. The status of the fuel level from both senders is sent from the REM over the communication network to the instrument cluster. The instrument cluster uses these inputs to determine the overall fuel level in the tank and illuminates the low fuel warning indicator if the fuel level is low.

Low Washer Fluid Warning Indicator
The washer fluid switch is hardwired directly to the FEM. The FEM monitors the washer fluid level status and sends it to the instrument cluster over the communication network to turn the low washer fluid warning indicator on or off.

Safety Belt Warning Indicator
Safety belt warning indication is accomplished through the safety belt switch, which is hardwired directly to the instrument cluster. The instrument cluster uses the ground or open input from the switch to determine if the safety belt is fastened. When the safety belt is fastened, the safety belt switch opens and removes the ground to the instrument cluster. When the safety belt is unfastened, the safety belt switch closes and grounds the circuit to the instrument cluster.

Indicator Lamps

CHECK FUEL CAP
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, signals a fault to the instrument cluster over the communication network. Once the PCM has detected a loose fuel cap and the CHECK FUEL CAP indicator is illuminated, the indicator remains illuminated until the fuel cap is secured and the ignition switch has been cycled one time.

Electronic Throttle Control Indicator
The PCM monitors the electronic throttle control and provides the instrument cluster with the electronic throttle control status over the communication network. When a system concern is detected, the PCM provides the instrument cluster with a signal commanding the instrument cluster to turn on the electronic throttle control lamp.

High Beam Indicator
The multifunction switch is hardwired directly to the instrument cluster. The headlamp status is then sent from the instrument cluster to the FEM and to the REM over the communication network.

Low Oil Pressure Indicator
The engine oil pressure switch is hardwired to the FEM, which monitors the oil pressure status. The oil pressure status is then sent from the FEM to the instrument cluster over the communication network to turn the low oil pressure indicator on or off.

Malfunction Indicator Lamp (MIL)
After the engine is started, the MIL proves out for a duration of 3 seconds. If the instrument cluster does not receive a message from the PCM within 5 seconds, it sends two messages to the PCM and attempts to establish communication. If the instrument cluster is unable to establish communication, the instrument cluster illuminates the MIL and logs a diagnostic trouble code (DTC).

Speed Control Indicator
The speed control status is monitored by the PCM and then relayed to the instrument cluster over the communication network. The speed control indicator illuminates when the speed control is set.

Traction Control Indicator
The status of the traction control is communicated to the instrument cluster from the ABS module via the communication network. When the traction control system is active, the ABS module sends a command to the instrument cluster to illuminate the traction control indicator.

Turn/Hazard Indicator
The multifunction switch is hardwired directly to the instrument cluster. The instrument cluster sends the signal from the multifunction switch to both the FEM and REM over the communication network while simultaneously illuminating the turn/hazard indicators. The FEM and the REM use these inputs from the instrument cluster to illuminate the exterior lighting as necessary.

Parameter Reset and Key Programming

NOTE:
- The instrument cluster parameters must be reset upon installation of a new instrument cluster.
- Both passive anti-theft system (PATS) keys are needed to carry out this procedure.

To reset the instrument cluster parameters and program the keys, complete the following procedure:
1. Connect the diagnostic tool.
2. Select the instrument cluster.
3. Select ENTER SECURITY ACCESS. Wait 10 minutes for security access to be granted.
4. Select PARAMETER RESET.
5. Disconnect the diagnostic tool.
6. Place the first PATS key in the ignition switch.
7. Turn the ignition switch to the ON position.
8. Turn the ignition switch to the OFF position.
9. Remove the key.
10. Place the second PATS key in the ignition switch.
11. Turn the ignition switch to the ON position.
12. Turn the ignition switch to the OFF position (the programming sequence is complete).

NOTE: If the vehicle fails to start following completion of the parameter reset and key programming sequence, clear the keep alive memory (KAM) by disconnecting the battery for five minutes.