Part 4

4WD INDICATOR

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

- 4WD Indicator Lamp-On Message - Each time the cluster receives an electronic 4WD 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 or the manual transfer case through the transfer case switch to determine when the 4WD mode is engaged. The TIPM 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 4WD indicator or the instrument cluster circuitry that controls the LED Component Tests and General Diagnostics.

4 LOW INDICATOR

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

- 4 Low Indicator Lamp-On Message - Each time the cluster receives an electronic 4 low 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 low 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 4 low indicator or the instrument cluster circuitry that controls the LED Component Tests and General Diagnostics.

TOW/HAUL INDICATOR

The tow/haul indicator gives an indication to the vehicle operator when the tow/haul function of the tow/haul 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 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, 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 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 will be illuminated. 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 indicator Component Tests and General Diagnostics.

TRANSMISSION RANGE INDICATOR

The electronic gear selector indicator gives an indication to the vehicle operator of the transmission gear that has been selected with the automatic transmission gear selector lever. This indicator is controlled by the instrument cluster circuit board based upon cluster programming. The cluster circuitry automatically configures itself for the proper transmission type based upon the hard wired transmission range sensor mux circuit input to the cluster.

The gear selector indicator information is displayed by the odometer/trip odometer Liquid Crystal Display (LCD) unit soldered onto the instrument cluster electronic circuit board, and the LCD will not display the gear selector indicator information after the ignition switch is turned to the OFF position. Each time the cluster is disconnected from battery current for more than about five minutes, it must configure itself for the automatic transmission type that is in the vehicle once it is reconnected to battery current. The instrument cluster circuitry configures the gear selector indicator based upon the following inputs from the transmission range sensor:

- Open Circuit - If the cluster is configured for an automatic transmission and the transmission range sensor mux circuit is open, the cluster circuitry controls the gear selector indicator display based upon an electronic selected gear message received from the Transmission Control Module (TCM) over the Controller Area Network (CAN) data bus. If the Transmission Range Sensor (TRS) mux circuit is open and no electronic selected gear messages are received from the TCM within two seconds, the instrument cluster circuitry will not display any gear selector position until the condition is resolved or until the ignition switch is turned to the OFF position, whichever occurs first.
- Resolved Circuit - If the transmission range sensor mux circuit is resolved, the cluster circuitry controls the gear selector indicator display based upon the resistance value of the hard wired input from the TRS. If the cluster is configured for an automatic transmission with a TRS input and detects a short to ground or an open in the TRS mux input, the instrument cluster circuitry will not display any gear selector position in the LCD display. The short-to-ground and open circuit conditions for the LCD display will continue until the condition is resolved or until the ignition switch is turned to the OFF position, whichever occurs first.

On vehicles with a TCM, the TCM continually monitors the TRS, then sends the proper message to the instrument cluster, also known as the CCN. On vehicles without a TCM, the CCN continually monitors the hard wired TRS multiplexed input. For further diagnosis of the gear selector indicator or the instrument cluster circuitry that controls this function Component Tests and General Diagnostics. For further diagnosis of the TRS on vehicles without a TCM, refer to the transmission range sensor in TRANSMISSION/TRANSAXLE/AUTOMATIC for the appropriate transmission.

TRANSMISSION TEMPERATURE INDICATOR

The transmission over-temperature indicator gives an indication to the vehicle operator when the transmission fluid temperature is excessive, which may lead to accelerated transmission component wear or failure. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received over the Controller Area Network (CAN) data bus from the PCM.

The transmission over-temperature 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 transmission over-temperature indicator is illuminated for about two seconds as a bulb test. The instrument cluster will turn ON the transmission over-temperature indicator for the following reasons:

- Trans Over-Temp Indicator Lamp-On Message - Each time the cluster receives an electronic trans over-temp indicator lamp-ON message from the PCM indicating that the transmission fluid temperature is 135 °C (275 °F) or higher, the indicator will be illuminated and a single chime tone is sounded. 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 chime tone feature will only repeat during the same ignition cycle if the indicator is cycled OFF and then ON again by the appropriate lamp-ON and lamp-OFF messages from the PCM.

The PCM continually monitors the transmission temperature sensor to determine the transmission operating condition. The PCM then sends the proper lamp-ON or lamp-OFF message to the instrument cluster, also known as the Cab Compartment Node (CCN). If the instrument cluster illuminates the transmission over-temperature indicator due to a high transmission oil temperature condition, it may indicate that the transmission or the transmission cooling system are being overloaded, or that they require service. For further diagnosis of the transmission over-temperature indicator or the instrument cluster circuitry that controls the LED Component Tests and General Diagnostics.

WAIT-TO-START INDICATOR

The wait-to-start indicator gives an indication to the vehicle operator when the air temperature within the diesel engine intake manifold is too cool for efficient and reliable engine starting, and that the intake air heater grids are energized in their pre-heat operating mode. This indicator is controlled by the CCN based upon cluster programming and electronic messages received by the from the PCM over the Controller Area Network (CAN) data bus.

The wait-to-start indicator, Light Emitting Diode (LED) is completely controlled by the CCN logic circuit, 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. The wait-to-start indicator will be turned ON for the following reasons:

- Wait-To-Start Indicator Lamp-On Message - Each time the CCN receives an electronic wait-to-start indicator lamp-ON message from the ECM indicating that the air temperature within the intake manifold is too cool for efficient and reliable engine starting, the wait-to-start indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message, until the ECM detects that the engine is running or until the ignition switch is turned to the OFF position, whichever occurs first.

The ECM continually monitors the engine intake air temperature sensor to determine when the intake air heater grids should be energized in their pre-heat operating mode. The ECM then sends the proper lamp-ON or lamp-OFF message to the CCN. For further diagnosis of the wait-to-start indicator or the instrument cluster circuitry that controls the indicator Component Tests and General Diagnostics.

WASHER FLUID INDICATOR

The washer fluid indicator gives an indication to the vehicle operator that the fluid level in the washer reservoir is low. This indicator is controlled by the instrument cluster logic circuit 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 washer fluid indicator function of the Liquid Crystal Display (LCD) 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 LCD washer fluid indication will always be OFF when the ignition switch is in any position except ON or START. The instrument cluster will turn ON the washer fluid indicator for the following reasons:

- Washer Fluid Indicator Lamp-On Message - Each time the cluster receives an electronic washer fluid indicator lamp-ON message from the TIPM indicating that a low washer condition has been detected for 60 consecutive seconds, the washer fluid indicator is illuminated and a single chime tone is sounded. The indicator remains illuminated until the cluster receives lamp-OFF messages for 60 consecutive seconds from the TIPM, 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 washer fluid indicator is cycled OFF and then ON again by the appropriate lamp-ON and lamp-OFF messages from the TIPM.

The TIPM continually monitors the washer fluid level switch in the washer reservoir to determine the level of the washer fluid. The TIPM 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 washer fluid indicator or the instrument cluster circuitry that controls the indicator Component Tests and General Diagnostics.

WATER-IN-FUEL INDICATOR

The water-in-fuel indicator gives an indication to the vehicle operator when there is excessive water in the fuel system. This indicator is controlled by the CCN based upon cluster programming and electronic messages received from the PCM over the Controller Area Network (CAN) data bus.

The water-in-fuel indicator 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 the CCN. Each time the ignition switch is turned to the ON position the water-in-fuel indicator is illuminated for about two seconds as a bulb test. The water-in-fuel indicator will be turned ON for the following reasons:

- Water-In-Fuel Indicator Lamp-On Message - Each time the CCN receives an electronic water-in-fuel lamp-ON message from the ECM indicating that there is excessive water in the diesel fuel system, the water-in-fuel indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the ECM, or until the ignition switch is turned to the OFF position, whichever occurs first.

The ECM continually monitors the water-in-fuel sensor to determine whether there is excessive water in the diesel fuel system. The ECM then sends the proper lamp-ON or lamp-OFF message to the CCN. For further diagnosis of the water-in-fuel indicator or the instrument cluster circuitry that controls the indicator Component Tests and General Diagnostics.

TURN SIGNAL INDICATOR

The turn signal indicators give an indication to the vehicle operator that the turn signal (left or right indicator flashing) or hazard warning (both left and right indicators flashing) have been selected and are operating. These indicators are controlled by transistors on the instrument cluster electronic circuit board based upon cluster programming, a hard wired multiplex input received by the cluster from the turn signal and hazard warning switch circuitry of the multi-function switch on the turn/hazard switch mux circuit, and electronic messages received from the Totally Integrated Power Module (TIPM) over the Controller Area Network (CAN) data bus.

Each turn signal 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, each 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 turn signal indicators for the following reasons:

- Turn Signal-On Input - Each time the cluster detects a turn signal-ON input from the turn signal switch circuitry of the multi-function switch on the turn/hazard switch mux circuit, it sends the appropriate electronic turn signal switch status messages to the TIPM over the CAN data bus. The TIPM responds to these messages by controlling a battery voltage output and the flash rate for either the right or left turn signal lamps. The TIPM also sends the appropriate electronic messages back to the cluster to control the flash rate of the turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the cluster electronic circuit board that emulates the sound emitted by a conventional turn signal flasher. The turn signal indicators continue to flash ON and OFF until the cluster receives a turn signal-OFF input from the multi-function switch, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Hazard Warning-On Input - Each time the cluster detects a hazard warning-ON input from the hazard warning switch circuitry of the multi-function switch on the turn/hazard switch mux circuit, it sends the appropriate electronic hazard switch status messages to the TIPM over the CAN data bus. The TIPM responds to these messages by controlling a battery voltage output and the flash rate for each of the right and left turn signal lamps. The TIPM also sends the appropriate electronic messages back to the cluster to control the flash rate of the turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the cluster electronic circuit board that emulates the sound emitted by a conventional hazard warning flasher. The turn signal indicators continue to flash ON and OFF until the cluster receives a hazard warning-OFF input from the multi-function switch.
- Lamp Out Mode - If the TIPM detects an ineffective turn signal lamp or circuit, it increases the flash rate for the remaining operative turn signals and sends an electronic message to the instrument cluster. The instrument cluster then increases the flash rate of the turn signal indicators and the click rate of the electromechanical relay to provide an indication of the problem to the vehicle operator.

The instrument cluster, also known as the CCN continually monitors the multi-function switch and electronic messages from the TIPM to determine the proper turn signal and hazard warning indicator operation. For further diagnosis of the turn signal indicators or the instrument cluster circuitry that controls the indicators Component Tests and General Diagnostics.