B0780

DTC B0780
Circuit Description
The 4LO indicator circuit consists of a indicator feed circuit and a 4LO indicator control circuit. When the 4LO mode has been selected by the driver, current is supplied to the 4LO indicator by the indicator lamp feed circuit, traveling through the 4LO indicator LEDs at which time the transfer case shift control module supplies the ground through the 4LO indicator control circuit.

Conditions for Setting the DTC
^ The system monitors the voltage on the 4LO indicator control circuit.
^ If the system detects a voltage 2.0 volts or less when the 4LO indicator is not commanded, the DTC is logged.
^ If the system detects a voltage 4.5 volts or more when the 4LO indicator is commanded, the DTC is logged.

Action Taken When the DTC Sets
The SERVICE 4WD indicator will be latched on for the remainder of the current ignition cycle.

Conditions for Clearing the DTC
^ The transfer case shift control module will clear the DTC if the condition for setting the DTC is not currently present.
^ A history DTC will clear after 100 consecutive ignition cycles without a fault present.
^ History DTCs can be cleared using a scan tool.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Look for the visual operation of the 4LO Indicator. Command both the ON and OFF states.
3. Helps determine if there is proper voltage supplied to the transfer case select switch.
4. Helps determine if there is a short to ground in the indicator control circuit.
5. Helps determine if there is an open in the indicator control circuit.
6. Tests the indicator feed circuit for an open or high resistance.
7. Tests the 4LO neutral control circuit for a short to ground.
8. Tests the 4LO neutral control circuit for an open or high resistance.