Part 3

OPERATION

LOW COOLANT INDICATOR

The coolant low indicator gives an indication to the vehicle operator when the diesel engine coolant level is low. This indicator is controlled by the IC logic circuit based upon programming and electronic messages received over the CAN data bus from the PCM.

The coolant low indicator function of the TFT display unit is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the TFT coolant low indication will always be OFF when the ignition switch is in any position except ON or START. The IC will turn ON the coolant low indicator for the following reasons:

- Coolant Low Indicator Lamp-On Message - Each time the cluster receives an electronic coolant low indicator lamp-ON message from the PCM indicating the engine coolant level is low, the coolant low textual warning and icon are illuminated and a single chime tone is sounded. The coolant low textual warning and icon remain 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 chime tone feature will only repeat during the same ignition cycle if the textual warning and icon are cycled OFF and then ON again by the appropriate messages from the PCM.

The PCM continually monitors the engine coolant level switch on the coolant bottle to determine the level of the engine coolant. The PCM then sends the proper lamp-ON or lamp-OFF message to the IC. If the IC turns ON the coolant low indicator and icon due to a low coolant level, it may indicate that the engine or the engine cooling system requires service.

For proper diagnosis of the engine coolant level switch, the PCM, the IC, the CAN data bus or the electronic communication related to coolant low indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

LOW FUEL INDICATOR

The low fuel indicator gives an indication to the vehicle operator when the level of fuel in the fuel tank becomes low. This indicator is controlled by a transistor on the IC circuit board based upon programming and a hard-wired input received by the cluster from the fuel level sending unit on the fuel pump module in the fuel tank. The IC will illuminate the low fuel indicator for about three seconds each time the ignition is turned to the ON position, during the bulb test.

The low fuel indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC 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 IC transistor. The IC will turn ON the low fuel indicator for the following reasons:

- Less Than 11 Percent Tank Full Input - The BCM provides a constant current source to the fuel level sending unit, and monitors a return input on a fuel level sense circuit. The resistance through the fuel level sending unit increases, as the fuel level falls, and decreases as the fuel level rises causing changes in the sense input voltage. Each time the fuel level sense input to the BCM indicates the fuel tank is about 11 percent full or less for 10 consecutive seconds and the vehicle speed is zero, or for 60 consecutive seconds and the vehicle speed is greater than zero, a message is sent to the IC, and the gauge needle is moved to the appropriate position on the gauge scale; the low fuel indicator is illuminated' and a single chime tone is sounded. The low fuel indicator remains illuminated until the fuel level sense input indicates that the fuel tank is greater than about 14 percent full for 10 consecutive seconds and the vehicle speed is zero, or for 60 consecutive seconds and the vehicle speed is greater than zero, or until the ignition switch is turned to the OFF position, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the low fuel indicator is cycled OFF and then ON again by the appropriate inputs from the fuel level sending unit.
- Less Than Empty Stop Input - Each time the IC receives a fuel level message from the BCM that indicates the fuel level in the fuel tank is less than the E (or Empty) gauge needle stop position for five consecutive seconds, the gauge needle is moved to the low end of the gauge scale and the low fuel indicator is illuminated immediately. This input would indicate that the fuel level sense input to the BCM is a short circuit.
- More Than Full Stop Input - Each time the IC receives a fuel level message from the BCM that indicates the fuel level in the fuel tank is more than the F (or Full) gauge needle stop position for five consecutive seconds, the gauge needle is moved to the low end of the gauge scale and the low fuel indicator is illuminated immediately. This input would indicate that the fuel level sense input to the BCM is an open circuit.

The BCM continually monitors the fuel tank sending unit to determine the level of fuel in the fuel tank. The BCM then sends the proper electronic fuel level message to IC, and other electronic modules in the vehicle over the CAN data bus. The BCM will store a DTC for any fault detected in the fuel level sense circuit.

For proper diagnosis of the fuel tank sending unit, the BCM, the IC, and the CAN data bus or the electronic communication related to low fuel indicator operation or fuel level data processing a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

LOW OIL PRESSURE INDICATOR

The low oil pressure indicator gives an indication to the vehicle operator when the engine oil pressure reading reflects a condition requiring immediate attention. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the cluster from the PCM over the CAN data bus.

The low oil pressure indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC 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 IC transistor. The IC will turn ON the low oil pressure indicator for the following reasons:

- Engine Oil Pressure Low Message - Each time the cluster receives an electronic engine oil pressure message from the PCM indicating the pressure is about 6.9 kPa (1 psi) or lower, the low oil pressure indicator will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the PCM message. The indicator remains illuminated solid or flashing until the cluster receives a message from the PCM indicating that the pressure is above about 6.9 kPa (1 psi), or until the ignition switch is turned to the OFF position, whichever occurs first. The cluster will only turn the indicator ON in response to low engine oil pressure if the engine speed is greater than zero.

The PCM continually monitors the engine oil pressure sensor to determine the engine oil pressure. The PCM then sends the proper messages to the IC. If the IC turns ON the indicator after the bulb test, it may indicate that the engine or the engine oiling system requires service.

For proper diagnosis of the engine oil pressure sensor, the PCM, the IC, the CAN data bus or the electronic communication related to low oil pressure indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

LOW TIRE PRESSURE INDICATOR

The Tire Pressure Monitor (TPM) indicator gives an indication to the vehicle operator of the status of the TPM system. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the cluster from the Wireless Ignition Node (WIN) over the CAN data bus. The IC will illuminate the TPM indicator for about three seconds each time the ignition is turned to the ON position, during the bulb test

The TPM indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC 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 provide a path to ground by the IC transistor. The IC will turn ON the TPM indicator for the following reasons:

- TPM Indicator Lamp-On Message - Each time the cluster receives an electronic TPM indicator lamp-ON message from the WIN, the TPM indicator or the TIRE LOW PRESSURE textual message will be illuminated. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the WIN message. The indicator or textual message remains illuminated 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.
- TPM Textual Warning Message - When the WIN detects certain monitored fault conditions, it will send electronic messages requesting the cluster display a textual warning message. Each time the cluster receives an electronic textual warning request message from the WIN, a SERVICE TIRE PRESS. SYSTEM textual message will appear within the cluster re-configurable dot matrix display to accompany a flashing TPM indicator or to replace the TPM TIRE LOW PRESSURE textual message. This message indicates that the WIN has detected a problem in one of the TPM system components.
- TPM Low Pressure Message - On vehicles equipped with the optional premium version of the TPM system, each time the cluster receives an electronic low pressure message from the WIN, a LEFT FRONT, RIGHT FRONT, LEFT REAR or RIGHT REAR LOW PRESSURE textual message will appear within the cluster re-configurable dot matrix display to accompany a solid TPM indicator. If the vehicle is equipped with a full-sized matching spare tire and wheel assembly, an electronic spare low pressure message from the WIN to the cluster will cause a SPARE LOW PRESSURE textual message will appear in the re-configurable display, but the TPM indicator will not illuminate. This message indicates that the WIN has received a low tire pressure input from the tire pressure sensor in the identified location on the vehicle. The premium TPM system is not offered in markets where rear fog lamps are an available option.
- Communication Error - If the cluster receives no TPM lamp-ON or lamp-OFF messages from the WIN for six consecutive seconds, the TPM indicator is illuminated by the IC. The indicator remains controlled and illuminated by the cluster until a valid lamp-ON or lamp-OFF message is received from the WIN.

The WIN performs a self-test each time the ignition switch is turned to the ON position to decide whether the TPM system is in good operating condition and whether the tire inflation pressures are too high or too low. The WIN then sends the proper lamp-ON or lamp-OFF message to the IC. If the IC turns ON the TPM indicator after the bulb test, it indicates that the inflation pressure of a tire is too low or that a malfunction has occurred and the TPM system is ineffective.

For proper diagnosis of the TPM system, the WIN, the IC, the CAN data bus or the electronic communication related to TPM indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

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 IC circuit board based upon programming and electronic messages received by the cluster from the PCM over the CAN data bus. The IC 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 IC logic circuit, and that logic will only allow this indicator to operate when the IC 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 IC transistor. The IC will turn ON the MIL for the following reasons:

- MIL Lamp-On Message - Each time the cluster receives an electronic 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 DTCs, if a problem does not recur, the PCM will send a lamp-OFF message automatically. Other DTCs may require that a fault be repaired and the PCM be reset before a lamp-OFF message will be sent. For more information on the PCM, and the DTC set and reset parameters, Emissions Control - Operation.
- Communication Error - If the cluster receives no lamp-ON or lamp-OFF messages from the PCM for 10 consecutive message cycles, the MIL is illuminated by the IC 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 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 message to the IC. If the IC 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.

For proper diagnosis of the fuel and emissions systems, the PCM, the IC, the CAN data bus or the electronic communication related to MIL operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

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 IC logic circuit based upon programming and electronic messages not being received over the CAN data bus from the BCM.

The no-bus indicator function of the odometer TFT display unit is completely controlled by the IC logic circuit. This logic only allows the indicator to operate when the IC receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the odometer TFT no-bus indicator is always off when the ignition switch is in any position except ON or START. The IC 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 IC continually monitors the CAN data bus to determine the status of many sensors and systems throughout the vehicle. If bus communication is interrupted, the IC cannot provide accurate displays and outputs.

Use a diagnostic scan tool is required for proper diagnosis of the no-bus indicator, the IC, the CAN data bus or the electronic communication related to no-bus indicator operation. Refer to the appropriate diagnostic information.

POSITION LAMP INDICATOR

The position lamp indicator gives an indication to the vehicle operator whenever the position lamps are illuminated. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the cluster from the BCM over the CAN data bus.

The position lamp indicator LED is completely controlled by the IC logic circuit, and that logic will allow this indicator to operate whenever the IC 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 IC transistor. The IC 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 BCM 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 BCM, or until the exterior lamp load shedding (battery saver) timed interval expires, whichever occurs first.

The BCM continually monitors electronic exterior lighting switch request messages from the IC to determine the appropriate outputs to the park lamp relay. The BCM activates or deactivates the park lamp relay then sends the proper lamp-ON or lamp-OFF message back to the IC.

For proper diagnosis of the position lamp system, the BCM, the IC, the CAN data bus or the electronic communication related to position lamp indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

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 IC circuit board based upon programming and electronic messages received by the cluster from the BCM over the CAN data bus.

The rear fog lamp indicator LED is completely controlled by the IC logic circuit, and that logic will allow this indicator to operate whenever the IC 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 IC transistor. The IC 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 BCM 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 BCM.
- Self Test - Each time the cluster is put through the self test, the rear fog lamp indicator will be turned ON, then OFF again during the bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.

The BCM continually monitors electronic exterior lighting switch request messages from the IC to determine the appropriate outputs to the rear fog lamp relay. The BCM then sends the proper lamp-ON or lamp-OFF message back to the IC.

For proper diagnosis of the rear fog lamp system, the BCM, the IC, the CAN data bus or the electronic communication related to rear fog lamp indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

REMOTE START INDICATOR

The remote start indicator gives an indication to the vehicle operator of the system status. This indicator is controlled by the IC logic circuit based upon programming and electronic messages received over the CAN data bus from the BCM and the Wireless Ignition Node (WIN).

The remote start indicator function of the TFT display unit is completely controlled by the IC logic circuit, and that logic will allow this indicator to operate whenever the IC receives a battery current input on the fused B(+) circuit. Therefore, the TFT remote start indications can be illuminated regardless of the ignition switch position. The IC will turn ON the remote start indicator for the following reasons:

- Key Not In Ignition - Remote Start Active Messages - Each time the cluster receives a combination of electronic key not inserted and remote start active messages from the BCM, the INSERT KEY TURN TO ON textual message is displayed. The message is displayed for about five seconds, until the cluster arbitrator logic determines that another display request has priority, or until the key is inserted into the ignition, whichever occurs first.
- Key In Ignition - Remote Start Active Messages - Each time the cluster receives a combination of electronic key inserted and remote start active messages from the BCM and ignition LOCK or ignition OFF messages from the WIN, the TURN TO ON textual message is displayed. The message is displayed for about five seconds, until the cluster arbitrator logic determines that another display request has priority, or until the ignition is turned to the ON position, whichever occurs first.

The BCM continually monitors the remote start system inputs and the WIN to determine the proper outputs to the remote start components. The BCM then sends the proper lamp-ON or lamp-OFF message to the IC.

For proper diagnosis of the remote start system, the WIN, the BCM, the IC, the CAN data bus or the electronic communication related to remote start indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

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 IC circuit board based upon programming and a hard-wired input from the seat belt switch in the driver side front seat belt buckle through the seat belt switch sense 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 IC logic circuit, and that logic will only allow this indicator to operate when the IC 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 IC transistor. The IC will turn ON the seat belt indicator for the following reasons:

- Seat Belt 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 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.
- Front Seat Belt Not Buckled - Beltminder Active - Following the seat belt reminder function, each time the cluster detects an open circuit on either of the front seat belt switch sense 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 front seat belt remains unbuckled about 60 seconds after the conclusion of the seat belt reminder function with the vehicle speed greater than about 8 kilometers-per-hour (5 miles-per-hour), the seat belt indicator will begin to cycle between flashing ON and OFF for 3 seconds, then lighting solid for 2 seconds. The seat belt indicator will continue to cycle between flashing and solid illumination for 13 complete cycles, until the seat belt switch sense inputs to the cluster are closed circuits to ground (seat belt switch closed = seat belt buckled), or until the ignition switch is turned to the OFF position, whichever occurs first.
- 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 switch sense 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 a closed circuit 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 switch sense circuit input to the IC. The seat belt switch input to the IC circuitry may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. For proper diagnosis of the IC, the CAN data bus or the electronic communication related to seat belt indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.