Part 3

MALFUNCTION INDICATOR

The MIL gives an indication to the vehicle operator when the PCM or the PCM has recorded a Diagnostic Trouble Code (DTC) for an On-Board Diagnostics II (OBDII) emissions-related circuit or component malfunction. The MIL is controlled by a transistor on the CCN circuit board based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus. These electronic messages are received from the PCM or PCM, depending on engine application.

The MIL Light Emitting Diode (LED) is completely controlled by the CCN 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 a transistor on the CCN circuit board. Each time the ignition switch is turned to the ON position the indicator is illuminated for about two seconds as a bulb test. The entire bulb test is a function of the PCM. The MIL will be turned ON for the following reasons:

- MIL Lamp-On Message - Each time the CCN receives an electronic MIL lamp-ON message from the PCM or ECM, the indicator will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the PCM. For some DTCs, if a problem does not recur, the PCM or ECM will send a lamp-OFF message automatically. Other DTCs may require that a fault be repaired and the PCM or ECM be reset before a lamp-OFF message will be sent. For more information on the PCM, the ECM, and the DTC set and reset parameters, refer to EMISSIONS.
- Communication Error - If the CCN receives no lamp-ON or lamp-OFF messages from the PCM or ECM for about 10 seconds, the MIL is illuminated by the instrument cluster to indicate a loss of bus communication. The indicator remains controlled and illuminated by the cluster until a valid message is received from the PCM.

The PCM or ECM continually monitors the fuel and emissions system circuits and sensors to decide whether the system is in good operating condition. The PCM or ECM then sends the proper lamp-ON or lamp-OFF message to the CCN. For further diagnosis of the MIL or the instrument cluster circuitry that controls the LED Component Tests and General Diagnostics. If the CCN turns ON the MIL after the bulb test, it may indicate that a malfunction has occurred and that the fuel and emissions systems may require service.

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 Liquid Crystal Display (LCD) 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 LCD 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 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 Liquid Crystal Display (LCD) 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 LCD 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 instrument cluster, also known as the 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 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 odometer display 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 LCD 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 instrument cluster, also known as the Cab Compartment Node (CCN).

REGENERATIVE BRAKE SYSTEM (RBS)

The Regenerative Brake System indicator gives an indication to the vehicle operator when the RBS system, or a circuit or component of the system is ineffective. 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 Regenerative Brake Controller (RBC) over the CAN data bus.

The RBS 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 RBS indicator for the following reasons:

- RBS Indicator Lamp-On Message - Each time the cluster receives an electronic RBS indicator lamp-on message from the RBC, the RBS indicator illuminates. The indicator remains illuminated until the cluster receives a lamp-off message from the RBC, or until the ignition switch turns to the OFF position, whichever occurs first.
- Communication Error - If the cluster receives no lamp-on or lamp-off messages from the RBC for five consecutive message cycles, the RBS indicator is illuminated. The indicator remains illuminated until the cluster receives a valid message from the RBC, or until the ignition switch is turned to the OFF position, whichever occurs first.

The RBC continually monitors the RBS circuits and sensors to decide whether the system is in good operating condition. The RBC then sends the proper lamp-on or lamp-off message to the instrument cluster, also known as the CCN. If the RBC sends a lamp-on message after the bulb test, it indicates that the RBC has detected a system malfunction or that the RBS system has become ineffective. The RBC stores a Diagnostic Trouble Code (DTC) for any malfunction it detects. Each time the RBS indicator fails to light due to an open or short in the cluster RBS indicator circuit, the cluster sends a message notifying the RBC of the condition, then the instrument cluster and the RBC will each store a DTC.

Use a diagnostic scan tool for proper diagnosis of the regenerative brake system, the RBC, the CCN, the CAN data bus or the electronic communication related to RBS indicator operation. Refer to the appropriate diagnostic information.

SEATBELT INDICATOR

The seatbelt indicator gives an indication to the vehicle operator of the status of the driver side front seatbelt. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and a hard wired input from the seatbelt switch in the driver side front seatbelt buckle through the seat belt indicator driver circuit.

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 input to the cluster.
- Driver Side Front Seatbelt Not Buckled - Beltminder Active - Following the seatbelt reminder function, each time the cluster detects an open circuit on the seat belt indicator driver circuit (seatbelt switch open = seatbelt unbuckled) with the ignition switch in the START or ON positions, the indicator will be illuminated. In addition, if the driver side front seat belt remains unbuckled about 60 seconds after the conclusion of the seatbelt reminder function with the vehicle speed greater than about 8 kilometers-per-hour (5 miles-per-hour), 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 the seat belt indicator driver input to the cluster is closed to ground (seatbelt switch closed = seatbelt buckled), or until the ignition switch is turned to the OFF position, whichever occurs first.
- Driver Side Front Seatbelt Not Buckled - Beltminder Inactive - Following the seatbelt reminder function, each time the cluster detects an open circuit on the seat belt indicator driver circuit (seatbelt switch open = seatbelt unbuckled) with the ignition switch in the START or ON positions, the indicator will be illuminated. The seatbelt indicator remains illuminated until the seat belt indicator driver input to the cluster is closed to ground (seatbelt switch closed = seatbelt buckled), or until the ignition switch is turned to the OFF position, whichever occurs first.
- Airbag Indicator Backup - If the instrument cluster detects a fault in the airbag indicator circuit it will send an electronic message indicating the fault to the Occupant Restraint Controller (ORC), then flash the seatbelt indicator ON and OFF. The cluster will continue to flash the indicator until the airbag indicator circuit fault is resolved, or until the ignition switch is turned to the OFF position, whichever occurs first.

SECURITY SYSTEM 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, hard wired inputs to the cluster from the various security system components, and electronic messages received by the cluster from the Wireless Ignition Node (WIN) via the Totally Integrated Power Module (TPIM) over the Controller Area Network (CAN) data bus.

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). 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 WIN. The instrument cluster will turn ON the security indicator for the following reasons:

- VTSS Indication - During the 16 second VTSS arming function, the cluster will 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 cluster flashes 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 cluster will 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 WIN, the security indicator will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the WIN message. The indicator remains illuminated solid or continues to flash until the cluster receives a lamp-OFF message from the WIN, 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 WIN 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 WIN.

The instrument cluster circuitry controls 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 WIN 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 WIN then sends the proper lamp-ON or lamp-OFF message to the instrument cluster, 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 from the TIPM 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. 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. The instrument cluster will turn ON the service 4WD indicator for the following reasons:

- 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 instrument cluster, also known as the CCN. For further diagnosis of the service 4WD indicator or the instrument cluster circuitry that controls the LED Component Tests and General Diagnostics.

4WD AUTO INDICATOR

The 4WD auto indicator gives an indication to the vehicle operator when the electronic transfer case has been shifted into the 4WD auto mode. 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 4WD auto 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 4WD auto indicator for the following reasons:

- 4WD Auto Indicator Lamp-On Message - Each time the cluster receives an electronic 4WD auto indicator lamp-ON message from the TIPM, the 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.

The TIPM continually monitors the electronic transfer case through the transfer case shift motor/mode sensor assembly to determine when the 4WD auto mode is engaged. The TIPM then sends the proper lamp-ON or lamp-OFF message to the instrument cluster, also known as the CCN. For further diagnosis of the 4WD auto indicator or the instrument cluster circuitry that controls the LED Component Tests and General Diagnostics.