For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC B0780: Four Wheel Drive Low Range (4LO) Indicator Circuit MalfunctionCircuit/System 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.
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. |
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
Description and Operation
Transfer Case Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
