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Home >> Dodge and Ram >> 2004 >> Durango 4WD V8-4.7L VIN N >> Repair and Diagnosis >> Transmission and Drivetrain >> Automatic Transmission/Transaxle >> Lamps and Indicators - A/T >> Shift Indicator - A/T >> Description and Operation >> 4WD Lock/Low Indicator

4WD Lock/Low Indicator

4WD LOCK INDICATOR




A 4WD lock indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with the optional four-wheel drive system and electronically shifted transfer case, this indicator is electronically disabled. This indicator consists of the text "4LOCK", which appears in the lower portion of the gear selector indicator Vacuum-Fluorescent Display (VFD) unit.

The gear selector indicator VFD is soldered onto the cluster electronic circuit board and is visible through a window with a smoked clear lens located below the tachometer in the lower right area of the cluster overlay. The dark lens over the VFD prevents the indicator from being clearly visible when it is not illuminated. The "4LOCK" text appears in an amber color and at the same lighting level as the gear selector indicator information when it is illuminated by the instrument cluster electronic circuit board. The 4WD lock indicator is serviced as a unit with the VFD in the instrument cluster.

The 4WD lock indicator gives an indication to the vehicle operator when the electronic transfer case has been shifted into the 4WD lock mode. This indicator is controlled by the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Front Control Module (FCM) (also known as the Integrated Power Module/IPM) over the Controller Area Network (CAN) data bus.

The 4WD lock 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 4WD lock indicator for the following reasons:

- 4WD Lock Lamp-On Message - Each time the cluster receives a 4WD lock lamp-on message from the FCM, the indicator will be illuminated. The indicator remains illuminated until the cluster receives a 4WD lock lamp-off message from the FCM, or until the ignition switch is turned to the Off position, whichever occurs first.
- Actuator Test - Each time the cluster is put through the actuator test, the 4WD lock indicator will be turned on, then off again during the VFD portion of the test to confirm the functionality of the VFD and the cluster control circuitry.

The FCM continually monitors the electronic transfer case through the transfer case shift motor/mode sensor assembly to determine when the 4WD lock mode is engaged. The FCM then sends the proper lamp-on or lamp-off messages to the instrument cluster. For further diagnosis of the 4WD lock indicator or the instrument cluster circuitry that controls the VFD.

For proper diagnosis of the transfer case shift motor/mode sensor, the FCM, the CAN data bus, or the electronic message inputs to the instrument cluster that control the 4WD lock indicator, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.


4WD LOW INDICATOR




A 4WD low indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with the optional four-wheel drive system and electronically shifted transfer case, this indicator is electronically disabled. This indicator consists of the text "4LO", which appears in the lower portion of the gear selector indicator Vacuum-Fluorescent Display (VFD) unit.

The gear selector indicator VFD is soldered onto the cluster electronic circuit board and is visible through a window with a smoked clear lens located below the tachometer in the lower right area of the cluster overlay. The dark lens over the VFD prevents the indicator from being clearly visible when it is not illuminated. The "4LO" text appears in an amber color and at the same lighting level as the gear selector indicator information when it is illuminated by the instrument cluster electronic circuit board. The 4WD low indicator is serviced as a unit with the VFD in the instrument cluster.

The 4WD 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 the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Front Control Module (FCM) (also known as the Integrated Power Module/IPM) over the Controller Area Network (CAN) data bus.

The 4WD low 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 4WD low indicator for the following reasons:

- 4WD Low Lamp-On Message - Each time the cluster receives a 4WD low lamp-on message from the FCM, the indicator will be illuminated. The indicator remains illuminated until the cluster receives a 4WD low lamp-off message from the FCM, or until the ignition switch is turned to the Off position, whichever occurs first.
- Actuator Test - Each time the cluster is put through the actuator test, the 4WD low indicator will be turned on, then off again during the VFD portion of the test to confirm the functionality of the VFD and the cluster control circuitry.

The FCM 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 FCM then sends the proper lamp-on or lamp-off messages to the instrument cluster. For further diagnosis of the 4WD low indicator or the instrument cluster circuitry that controls the VFD.

For proper diagnosis of the transfer case shift motor/mode sensor, the FCM, the CAN data bus, or the electronic message inputs to the instrument cluster that control the 4WD low indicator, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
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