• | 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. |
The 4WD LO circuit is used to notify the powertrain control module (PCM) that the vehicle is in 4WD low range. The PCM supplies 12 volts to this circuit. The transfer case shift control module grounds this circuit when the vehicle is in 4WD low range.
This DTC detects a short to ground, short to voltage or an open in the 4WD LO circuit.
• | The ignition is ON. |
• | System voltage is 9-18 volts. |
• | After the transfer case shift control module grounds the output, the 4WD LO circuit, and reads back a high voltage, the DTC sets. The system does not attempt setting the DTC again for 5 seconds. |
• | The transfer case shift control module reads back a high voltage when a low voltage is expected on the 4WD LO circuit. |
• | Transmission shift points may be affected. |
• | The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle. |
• | 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. |
Transfer Case Control Schematics
Transfer Case Description and Operation
Control Module References for scan tool information.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.