overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B0775 01
- 4 High Indicator Circuit Short to Battery
DTC B0775 06
- 4 High Indicator Circuit Short to Ground or Open
Diagnostic Fault Information
Circuit/System Description
The 4 High indicator circuit consists of a light emitting diode (LED), a LED feed circuit and a LED control circuit. The indicator dimming control
circuit is the LED feed circuit and continuously supplies voltage to the 2 High, Auto 4WD, and 4 High LEDs. When the 4 High mode has been
selected by the driver, the transfer case shift control module (TCCM) provides a ground through the 4 High indicator control circuit illuminating the
LED. The TCCM tests the 4 High indicator circuit for unexpected voltage by monitoring the B+ supplied by the BCM on the indicator dimming
control circuit by grounding the 4 High indicator control circuit for 2 seconds during the bulb test at key ON.
Conditions for Running the DTC
B0775 01
* Ignition ON
* System voltage 10-18 V
* Instrument panel lights not dimmed.
* Daylight running lights MUST be commanded ON.
* Circuit tested when the AWD indicator is commanded ON.
B0775 06
* Ignition ON
* System voltage 10-18 V
* Instrument panel lights not dimmed.
* Daylight running lights MUST be commanded ON.
* Circuit tested when the AWD indicator is commanded OFF.
Conditions for Setting the DTC
B0775 01
The TCCM detects 3.4 V or greater on the AWD indicator control circuit when the AWD indicator is commanded ON.
B0775 06
The TCCM detects 1.6 V or less for 1.5 seconds on the AWD indicator control circuit when the AWD indicator is commanded OFF.
Action Taken When the DTC Sets
Normal operation, the SERVICE 4WD indicator is not commanded ON. Driver is informed of fault via bulb inspection.
Conditions for Clearing the DTC
* The TCCM clears the DTC once the condition for setting the DTC is no longer present.
* A history DTC clears after 40 consecutive warm-up cycles without a fault present.
* History DTCs can be cleared using a scan tool.
Diagnostic Aids
* A TRUE B+ has enough current to light a test light.
* A DIAGNOSTIC B+ is a low current circuit that DOES NOT have enough current to light a test light.
* A short to ground on the AWD indicator control circuit will cause the AWD indicator to remain ON at all times.
* An open or high resistance on the AWD indicator control circuit will cause the AWD indicator to be inoperative during the 2 second bulb
