B0780
DTC B0780
Circuit Description
The 4LO indicator circuit consists of an LED dimming supply circuit and a 4LO indicator control circuit. When the 4LO mode is selected, current is supplied to the 4LO indicator by the LED dimming supply 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B0780 Four Wheel Drive Low Range (4LO) Indicator Circuit Malfunction
Conditions for Running the DTC
- The ignition is ON.
- System voltage is 9-18 volts.
Conditions for Setting the DTC
- The system monitors the voltage on the 4LO indicator control circuit.
- If the system detects a voltage of 3 volts or less for 1.5 seconds when the 4LO indicator is not commanded, the DTC is logged.
- If the system detects a voltage of 4.5 volts or greater when the 4LO indicator is commanded, the DTC is logged.
Action Taken When the DTC Sets
The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
Conditions for Clearing the DTC
- The transfer case shift control module clears the DTC if the condition for setting the DTC is not currently present.
- A history DTC clears 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. This step looks for the visual operation of the 4LO indicator. Command both the ON and OFF states.
3. This step helps determine if proper voltage is supplied to the transfer case select switch.
4. This step helps determine if there is a short to ground in the indicator control circuit.
5. This step helps determine if there is an open in the indicator control circuit.
6. This step tests the indicator feed circuit for an open or high resistance.
7. This step tests the 4LO neutral control circuit for a short to ground.
8. This step tests the 4LO neutral control circuit for an open or high resistance.
