U0102high severityNetwork
Lost Communication with Transfer Case Control Module
on 2004 Subaru Legacy 3.0L H6 · AWD
What this code means
Cannot communicate with the transfer case control module that manages AWD/4WD operation.
Symptoms
- 4WD/AWD warning light on
- Transfer case stuck in mode
- Cannot switch between 2WD and 4WD
- Service 4WD message
Common causes
- Transfer case module power failure
- CAN bus wiring to module
- Transfer case module failure
- Fuse blown
- Connector corrosion
Diagnostic steps
- Check transfer case module fuse
- Test module power and ground
- Inspect CAN bus wiring to module
- Try direct communication with module
- Check connector for corrosion
Repair notes
Check fuses and power supply first. Common on trucks after water fording.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
U0002
High Speed CAN Communication Bus Performance
U0003
High Speed CAN Communication Bus (+) Open
U0004
High Speed CAN Communication Bus (+) Low
U0005
High Speed CAN Communication Bus (+) High
U0006
High Speed CAN Communication Bus (-) Open
U0007
High Speed CAN Communication Bus (-) Low
U0008
High Speed CAN Communication Bus (-) High
U0009
High Speed CAN Communication Bus Shorted Together
U0010
Medium Speed CAN Communication Bus