What it means
The driveline control module monitors its driver for the transfer case control circuit and sets this code when the driver detects a fault controlling that circuit.
How it works
The driveline control module uses an electronic driver to command the transfer case, which changes how drive is distributed through the drivetrain. It monitors the transfer case control circuit for an electrical fault while issuing commands. An open, short, or driver fault can set C00A5 and leave AWD or 4WD unavailable or limited.
Common causes
Most likely first.
- Open or short in the transfer case control circuit
- Damaged wiring or connector
- Power or ground fault
- Driveline control module driver fault
Symptoms
- 4WD or AWD warning
- 4WD or AWD may be unavailable or limited
How to diagnose it
- Read driveline-module codes and freeze-frame data first to see when the transfer case circuit fault occurred and whether related supply or communication faults are stored.
- Check transfer case command and status data, if available, to see whether the reported mode follows the module's request.
- Inspect the transfer case connector and harness for corrosion, loose pins, water intrusion, or damage from nearby moving parts.
- Check the driveline control module and transfer case power and ground connections using the manufacturer's procedure.
- Test the transfer case control circuit for opens or shorts using the vehicle wiring diagram and compare results with the manufacturer's specification before suspecting the module driver.
Common fixes
- Clean and secure the transfer case connector.
- Repair damaged wiring or terminals in the transfer case control circuit.
- Correct a verified module or transfer case power and ground fault.
- Replace the transfer case component only if its internal fault is confirmed.
- Replace or reprogram the driveline control module only after confirming its transfer case driver is faulty.
Can I keep driving?
AWD or 4WD may be unavailable or stuck in a mode, so avoid relying on it for slippery surfaces or demanding terrain. Stop if the drivetrain binds, makes unusual noises, or loses drive.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.