Part 3

OPERATION

MALFUNCTION INDICATOR LAMP

The Malfunction Indicator Lamp (MIL) gives an indication to the vehicle operator when the PCM has recorded a 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 programming and electronic messages received from the PCM over the CAN data bus. The CCN will illuminate the MIL indicator for about fifteen seconds each time the ignition is turned to the ON position, during the bulb test.

The MIL 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 the CCN transistor. The CCN will also turn on the MIL for the following reasons:

- MIL Lamp-ON Message - Each time the CCN receives a MIL lamp-on message from the PCM, the indicator will be illuminated. The indicator can be flashed on and off, or illuminated solid, as dictated by the PCM message. For some DTC's, if a problem does not recur, the PCM will send a lamp-off message automatically. Other DTC's may require that a fault be repaired and the PCM be reset before a lamp-off message will be sent.
- Communication Error - If the CCN receives no messages from the PCM for ten consecutive message cycles, the MIL is illuminated by the CCN to indicate a loss of bus communication. The indicator remains illuminated until a valid message is received from the PCM.

The PCM continually monitors the fuel and emissions system circuits and sensors to decide whether the system is in good operating condition. The PCM then sends the proper lamp-on or lamp-off messages to the CCN. 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.

OVERDRIVE OFF INDICATOR

The overdrive off indicator gives an indication to the vehicle operator when the electronically controlled overdrive feature of the automatic transmission has been disabled. This indicator is controlled by a transistor on the CCN circuit board based upon programming and electronic messages received from the PCM over the CAN data bus.

The overdrive off indicator 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 the CCN transistor. The CCN will illuminate the overdrive off indicator for the following reasons:

- Overdrive OFF Indicator Lamp-ON Message - Each time the CCN receives an electronic overdrive off indicator lamp-ON message from the PCM indicating that the overdrive-OFF position of the tow/haul switch has been selected, the indicator will be illuminated. The indicator remains illuminated until the CCN 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 overdrive switch to determine the proper outputs to the automatic transmission. The PCM then sends the proper lamp-ON or lamp-OFF message 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 CCN circuit board based upon programming and electronic messages received from the TIPM over the CAN data bus.

The rear fog lamp indicator LED is completely controlled by the CCN 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 CCN transistor. The CCN will turn ON the rear fog lamp indicator for the following reasons:

- Rear Fog Indicator Lamp-ON Message - Each time the CCN 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 CCN 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 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.

SEAT BELT INDICATOR

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

The seat belt indicator also includes a programmable enhanced seat belt 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 seat belt indicator 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 the CCN transistor. The CCN will turn on the seat belt indicator for the following reasons:

- Seat Belt Reminder Function - Each time the CCN receives a battery current input on the fused ignition switch output (run-start) circuit, the indicator will be illuminated as a seat belt 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 seat belt switch input to the cluster.
- Driver Side Front Seat Belt Not Buckled - Beltminder Active - Following the seat belt reminder function, each time the CCN detects an open circuit on the seat belt indicator driver circuit (seat belt switch open = seat belt 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 after the conclusion of the seat belt reminder function, with the vehicle speed greater than about5 MPH (8 Kph), the seat belt indicator will begin to cycle between flashing on and off for three seconds, then lighting solid for two seconds. The seat belt indicator will continue to cycle between flashing and solid illumination for thirteen complete cycles, until the seat belt indicator driver input to the cluster is closed to ground (seat belt switch closed = seat belt buckled), or until the ignition switch is turned to the OFF position, whichever occurs first.
- Driver Side Front Seat Belt Not Buckled - Beltminder Inactive - Following the seat belt reminder function, each time the cluster detects an open circuit on the seat belt indicator driver circuit (seat belt switch open = seat belt unbuckled) with the ignition switch in the START or ON positions, the indicator will be illuminated. The seat belt indicator remains illuminated until the seat belt indicator driver input to the cluster is closed to ground (seat belt switch closed = seat belt buckled), or until the ignition switch is turned to the OFF position, whichever occurs first.

The seat belt switch is connected in series between ground and the seat belt indicator driver input to the instrument cluster. The seat belt switch input to the instrument cluster circuitry may be diagnosed using conventional diagnostic tools and methods. Refer to the appropriate wiring information.

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 models 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 CCN circuit board based upon programming, hard-wired inputs to the CCN from the various security system components, electronic messages received from the WIN over the CAN data bus. The CCN will illuminate the security indicator for about three seconds each time the ignition is turned to the ON position, during the bulb test.

The security indicator LED is completely controlled by the CCN 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 CCN transistor. The CCN will also turn on the security indicator for the following reasons:

- VTSS Indication - During the sixteen 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 thirty seconds after the VTSS is disarmed.
- SKIS Lamp-ON Message - Each time the CCN receives a SKIS 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 CCN receives a SKIS 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 CCN receives no SKIS lamp-on or lamp-off messages from the WIN for ten consecutive message cycles, the security indicator is illuminated by the CCN. The indicator remains controlled and illuminated by the CCN until a valid SKIS lamp-on or lamp-off message is received.

The CCN 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 messages to the CCN. If the instrument 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 inoperative.

SWAY BAR DISCONNECT INDICATOR

The front sway bar disconnect indicator gives an indication to the vehicle operator when the locking mechanism of the front sway bar of vehicles equipped with the optional off-road package is disengaged. This indicator is controlled by a transistor on the CCN circuit board based upon programming and electronic messages received from the TIPM over the CAN data bus

The front sway bar disconnect indicator 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 the instrument cluster transistor. The CCN will illuminate the front sway bar disconnect indicator for the following reasons:

- Front Sway Bar Disconnect Indicator Lamp-ON Message - Each time the CCN receives an electronic front sway bar disconnect 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 an input from the front sway bar disconnect solenoid to determine the status of the front sway bar disconnect mechanism. The TIPM then sends the proper lamp-ON or lamp-OFF message to the CCN.

TRACTION CONTROL INDICATOR

The traction control indicator gives an indication to the vehicle operator when the electronic Traction Control System (TCS) has been activated. This indicator is controlled by the CCN circuit board based upon programming and electronic messages received from the CAB over the CAN data bus. The CCN will illuminate the traction control indicator for about four seconds each time the ignition is turned to the ON position, during the bulb test.

The traction control indicator 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 indicator will always be off when the ignition switch is in any position except ON or START. The indicator only illuminates when it is switched to ground by the instrument cluster circuitry. The instrument cluster will turn on the traction control indicator for the following reasons:

- Traction Control Lamp-ON Message - Each time the CCN receives a traction control lamp-ON message from the CAB indicating that the TCS has been activated, the traction control indicator will be illuminated. The indicator remains illuminated until a traction control lamp-off message from the CAB is received, or until the ignition switch is turned to the OFF position, whichever occurs first.

The CAB continually monitors the traction control switch to determine the proper outputs to the components of the ABS. The CAB then sends the proper traction control lamp-on and lamp-OFF messages to the CCN.