U0102Lost Communication With Transfer Case Control Module
- Generic OBD-II code · Network
- How the car detects it
- U0102 is logged when the transfer case control module, which shifts between two- and four-wheel drive and between high and low range, stops sending. GM's 2025 engine controllers expect frame $035 and fail it when gaps exceed 425 ms within a 5 s window; the code is Type C, emissions-neutral and without MIL. The earlier two-mode hybrid trucks (2012 table) used Type B with 500 ms detection between 10 and 18 V. Ford's 2023 diesel controllers allow 5 s before flagging the TCCM. Bulletin 08-07-30-021H lists U0102 among GMLAN codes caused by shared bus faults. The driver mostly sees a 4WD warning and a transfer case left in its last range; engine and gearbox keep running. U0403 covers implausible data from the same module.
- What you may notice
- 4WD or AWD warning, range selection ignored
- Transfer case stays in its last mode
- Usually no MIL
- Likely causes
- LikelyTransfer case module without power or ground
- PossibleWater or corrosion in the module connector (often mounted low on the frame)
- PossibleDamaged CAN lines to the transfer case module
- RareTransfer case module internally faulty
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.