Part 3

OPERATION

NO BUS INDICATOR

The no-bus indicator gives an indication to the vehicle operator when the electronic communication data bus is ineffective. This indicator is controlled by the instrument cluster logic circuit based upon cluster programming and electronic messages not being received over the Controller Area Network (CAN) data bus from the Front Control Module (FCM).

The no-bus indicator function of the odometer Vacuum Fluorescent Display (VFD) unit is completely controlled by the instrument cluster logic circuit. This logic only allows the indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the odometer VFD no-bus indicator is always off when the ignition switch is in any position except ON or START. The instrument cluster turns ON the no bus indicator for the following reasons:

- No Electronic Communication Messages - Each time the ignition switch is turned to the ON position and the cluster does not receive electronic communication messages over the CAN data bus, the no-bus indicator illuminates. The indicator remains illuminated until CAN bus communication is restored or until the ignition switch turns to the OFF position, whichever occurs first.

The instrument cluster, also known as the Cab Compartment Node (CCN) continually monitors the CAN data bus to determine the status of many sensors and systems throughout the vehicle. If bus communication is interrupted, the CCN cannot provide accurate displays and outputs.

NO FUSE INDICATOR

The no fuse indicator gives an indication to the vehicle operator when the Ignition Off Draw (IOD) fuse is ineffective or is not installed. This indicator is controlled by the instrument cluster logic circuit based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus from the Totally Integrated Power Module (TIPM).

The no fuse indicator function of the odometer Vacuum Fluorescent Display (VFD) unit is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the odometer VFD no fuse indication will always be OFF when the ignition switch is in any position except ON or START. The instrument cluster will turn ON the no fuse indicator for the following reasons:

- No Fuse Indicator Lamp-On Message - Each time the ignition switch is turned to the ON position and the cluster receives an electronic no fuse indicator lamp-ON message from the TIPM indicating that the IOD fuse is missing or ineffective, the no fuse indicator will be illuminated. The indicator remains illuminated for about three seconds, until the IOD fuse is installed, until the trip odometer reset switch button is depressed or until the ignition switch is turned to the OFF position, whichever occurs first.

The TIPM continually monitors the IOD circuit to determine the status of the IOD fuse, then sends the proper lamp-ON or lamp-OFF message to the ElectroMechanical Instrument Cluster (CCN) (also known as the Cab Compartment Node/CCN) over the CAN data bus.

OIL CHANGE INDICATOR

The change oil indicator gives an indication to the vehicle operator when a duty-cycle algorithm contained within the software of the Powertrain Control Module (PCM) determines that a recommended oil change interval has been attained. This indicator is controlled by the instrument cluster logic circuit based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus from the PCM.

The change oil indicator function of the Vacuum Fluorescent Display (VFD) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the VFD change oil indication will always be OFF when the ignition switch is in any position except ON or START. The instrument cluster will turn ON the change oil indicator for the following reasons:

- Change Oil Indicator Lamp-On Message - Each time the ignition switch is turned to the ON position and the cluster receives an electronic change oil indicator lamp-ON message from the PCM indicating that a duty-cycle based recommended oil change interval has been attained, the change oil indicator will be illuminated for about three seconds, until the trip odometer reset switch button is depressed, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Change Oil Indicator Reset Procedure - Once an engine oil change has been completed, the PCM duty cycle counters can be reset using the following procedure. Turn the ignition switch to the ON position, but DO NOT start the engine. Slowly depress and release the accelerator pedal fully three times within ten seconds. Turn the ignition switch to the OFF position. If the change oil indicator illuminates the next time the engine is started, repeat this procedure.

The PCM continually monitors numerous sensor inputs to determine the duty-cycles to which the engine is being subjected. A pre-programmed algorithm within the PCM then determines when to send the proper lamp-ON or lamp-OFF message to the ElectroMechanical Instrument Cluster (CCN) (also known as the Cab Compartment Node/CCN).

POSITION INDICATOR

The position lamp indicator gives an indication to the vehicle operator whenever the position lamps (exterior lighting) are illuminated. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Totally Integrated Power Module (TIPM) over the Controller Area Network (CAN) data bus.

The position lamp indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will allow this indicator to operate whenever the instrument cluster receives a battery current input on the fused B(+) circuit. Therefore, the LED can be illuminated regardless of the ignition switch position. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the position lamp indicator for the following reasons:

- Position Lamp Indicator Lamp-On Message - Each time the cluster receives an electronic position lamp indicator lamp-ON message from the TIPM indicating the position lamps are turned ON, the position lamp indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the TIPM, or until the exterior lamp load shedding (battery saver) timed interval expires, whichever occurs first.

The TIPM continually monitors electronic exterior lighting switch request messages from the ElectroMechanical Instrument Cluster (CCN) (also known as the Cab Compartment Node/CCN) to determine the appropriate outputs to the park lamp relay. The TIPM activates or deactivates the park lamp relay then sends the proper lamp-ON or lamp-OFF message back to the CCN.

REAR FOG LAMP INDICATOR

The rear fog lamp indicator gives an indication to the vehicle operator whenever the rear fog lamps are illuminated. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Totally Integrated Power Module (TIPM) over the Controller Area Network (CAN) data bus.

The rear fog lamp indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will allow this indicator to operate whenever the instrument cluster receives a battery current input on the fused B(+) circuit. Therefore, the LED can be illuminated regardless of the ignition switch position. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the rear fog lamp indicator for the following reasons:

- Rear Fog Indicator Lamp-On Message - Each time the cluster receives an electronic rear fog indicator lamp-ON message from the TIPM indicating the rear fog lamps are turned ON, the rear fog lamp indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the TIPM, or until the exterior lamp load shedding (battery saver) timed interval expires, whichever occurs first.

The TIPM continually monitors electronic exterior lighting request messages from the ElectroMechanical Instrument Cluster (CCN) (also known as the Cab Compartment Node/CCN) to determine the appropriate outputs to the rear fog lamps. The TIPM activates or deactivates the rear fog lamps then sends the proper lamp-ON or lamp-OFF message back to the CCN.

SEATBELT INDICATOR

The seatbelt indicator gives an indication to the vehicle operator of the status of the front seat belts. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic driver side and passenger side front seat belt switch status messages received over the Controller Area Network (CAN) data bus.

The seatbelt indicator also includes a programmable enhanced seatbelt reminder or BELTMINDER feature that is enabled when the vehicle is shipped from the factory. This BELTMINDER feature can be disabled and enabled by the customer using a specific programming event sequence, or by the dealer using a diagnostic scan tool.

The seatbelt indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the seatbelt indicator for the following reasons:

- Seatbelt Reminder Function - Each time the cluster receives a battery current input on the fused ignition switch output (run-start) circuit, the indicator will be illuminated as a seatbelt reminder for about six seconds, or until the ignition switch is turned to the OFF position, whichever occurs first. This reminder function will occur regardless of the status of the seatbelt switch inputs to the cluster.
- Front Seatbelt Not Buckled Message - Beltminder Active - Following the seatbelt reminder function, each time the cluster receives an electronic driver side or passenger side front seat belt unbuckled status message with the ignition switch in the START or ON positions, the indicator will be illuminated. In addition, if a front seat belt remains unbuckled about 4 seconds after the conclusion of the seatbelt reminder function, the seatbelt indicator will begin to cycle between flashing ON and OFF for 3 seconds, then lighting solid for 2 seconds. The seatbelt indicator will continue to cycle between flashing and solid illumination for 13 complete cycles, until electronic driver side and passenger side front seat belt buckled status messages are received, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Front Seatbelt Not Buckled Message - Beltminder Inactive - Following the seatbelt reminder function, each time the cluster receives an electronic driver side or passenger side front seat belt unbuckled status message with the ignition switch in the START or ON positions, the indicator will be illuminated. The seatbelt indicator remains illuminated until electronic driver side and passenger side front seat belt buckled status messages are received, or until the ignition switch is turned to the OFF position, whichever occurs first.

The driver side seat belt switch is connected in series between ground and the seat belt switch sense circuit input to the Totally Integrated Power Module (TIPM), while the passenger side seat belt switch is connected between an output and an input of the Occupant Restraint Controller (ORC). The ORC also monitors inputs from the Occupant Classification Module (OCM) to determine whether the passenger side front seat is occupied. The TIPM and the ORC continually monitor these inputs, then send the proper status messages to the ElectroMechanical Instrument Cluster (CCN) (also known as the Cab Compartment Node/CCN) over the CAN data bus.

SECURITY INDICATOR

The security indicator gives an indication to the vehicle operator when the Vehicle Theft Security System (VTSS) is arming or is armed. On vehicles equipped with the Sentry Key Immobilizer System (SKIS), the security indicator also gives an indication to the vehicle operator of the status of the SKIS. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming, and electronic security indicator request messages received by the cluster from the Totally Integrated Power Module (TIPM) or the Sentry Key REmote Entry Module (SKREEM) (also known as the Wireless Control Module/WCM) over the Controller Area Network (CAN) data bus. Each time the ignition switch is turned to the ON position the security indicator illuminates for about two seconds as a bulb test. The entire bulb test is a function of the SKREEM.

The security indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will allow this indicator to operate whenever the instrument cluster receives a battery current input on the fused B(+) circuit. Therefore, the LED can be illuminated regardless of the ignition switch position. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. Depending upon the programmed condition, the indicator can be illuminated solid, flashed at a slow rate (0.5 Hertz, 12.5 percent duty cycle), or flashed at a fast rate (1 Hertz, 50 percent duty cycle). The instrument cluster will turn ON the security indicator for the following reasons:

- Security Indicator Lamp-On Message - During the 16 second VTSS arming function, the TIPM will request the cluster flash the security indicator ON and OFF repeatedly at a steady, fast rate to indicate that the VTSS is in the process of arming. Following successful VTSS arming, the TIPM will request the cluster flash the security indicator ON and OFF continuously at a slower rate to indicate that the VTSS is armed. The security indicator continues flashing at the slower rate until the VTSS is disarmed or triggered. If the VTSS has alarmed and rearmed, the TIPM will request the cluster flash the security indicator at a steady, slow rate for about 30 seconds after the VTSS is disarmed.
- SKIS Indicator Lamp-On Message - Each time the cluster receives an electronic SKIS indicator lamp-ON message from the SKREEM, the security indicator will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the SKREEM message. The indicator remains illuminated solid or continues to flash until the cluster receives a lamp-OFF message from the SKREEM, or until the ignition switch is turned to the OFF position, whichever occurs first. For more information on the SKIS and the security indicator control parameters, Vehicle Theft Security System - Operation.
- Communication Error - If the cluster receives no lamp-ON or lamp-OFF messages from the TIPM or the SKREEM for 10 consecutive message cycles, the security indicator is illuminated by the instrument cluster. The indicator remains controlled and illuminated by the cluster until a valid lamp-ON or lamp-OFF message is received from the SKREEM.

The TIPM sends electronic security indicator request messages to control the security indicator whenever the ignition switch is in the OFF position and the VTSS is arming, armed, or alarming. Whenever the ignition switch is in the ON or START positions, the SKREEM performs a self-test to decide whether the SKIS is in good operating condition and whether a valid key is present in the ignition lock cylinder. The SKREEM then sends the proper lamp-ON or lamp-OFF message to the ElectroMechanical Instrument Cluster (CCN) (also known as the Cab Compartment Node/CCN). If the cluster flashes the security indicator upon ignition ON, or turns ON the security indicator solid after the bulb test, it indicates that a SKIS malfunction has occurred or that the SKIS is ineffective.

SERVICE 4WD INDICATOR

The service 4WD indicator gives an indication to the vehicle operator when the Totally Integrated Power Module (TIPM) has recorded a Diagnostic Trouble Code (DTC) for an electronic transfer case circuit or component malfunction. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster over the Controller Area Network (CAN) data bus.

The service 4WD indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn ON the service 4WD indicator for the following reasons:

- Bulb Test - Each time the ignition switch is turned to the ON position the service 4WD indicator is illuminated for about two seconds as a bulb test.
- Service 4WD Indicator Lamp-On Message - Each time the cluster receives an electronic service 4WD indicator lamp-ON message from the TIPM, the service 4WD indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the TIPM, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Communication Error - If the cluster receives no lamp-ON or lamp-OFF messages from the TIPM for 10 seconds, the service 4WD indicator is illuminated by the cluster to indicate a loss of TIPM communication. The indicator remains controlled and illuminated by the cluster until a valid message is received from the TIPM.

The TIPM continually monitors the electronic transfer case control circuits and transfer case shift motor/mode sensor assembly to determine the condition of the system. The TIPM then sends the proper lamp-ON or lamp-OFF message to the ElectroMechanical Instrument Cluster (CCN).

TOW/HAUL INDICATOR

The tow/haul indicator gives an indication to the vehicle operator when the tow/haul function switch has been selected, revising the shift schedule of the electronically controlled automatic transmission. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus.

The tow/haul indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit. This logic only allows the indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED is always off when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster turns on the tow/haul indicator for the following reasons:

- Tow/Haul Indicator Lamp-On Message - Each time the cluster receives an electronic tow/haul indicator lamp-on message from the PCM indicating that the tow/haul shift schedule has been selected, the indicator illuminates. The indicator remains illuminated until the cluster receives a lamp-off message from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first.

The PCM continually monitors the tow/haul switch to determine the proper outputs to the automatic transmission. The PCM then sends the proper lamp-on or lamp-off message to the instrument cluster, also known as the Cab Compartment Node (CCN). For further diagnosis of the tow/haul indicator or the instrument cluster circuitry that controls the LED, Testing and Inspection.