B0790: Transfer Case Neutral Indicator Circuit Malfunction (GM)
Severity: medium
What it means: On GM trucks such as the Hummer H3, the transfer case control module (the computer that runs the four-wheel-drive system) sees the wrong voltage on the circuit for the transfer case Neutral indicator light. It usually points to wiring, a connector, or the 4WD selector switch.
Safe to drive? Usually yes on the road, but the Service 4WD light stays on and four-wheel-drive shifting may not work correctly. Get it checked before you need 4WD.
Common symptoms
- Service 4WD light on
- Neutral or 4WD indicator lights not working correctly
- Other body or 4WD codes stored at the same time
Likely causes, ranked
- Wet or corroded wiring or connectors (water leaks)Shop
- Faulty transfer case mode or selector switchShop
- Failed transfer case control moduleShop
Vehicle-specific notes
- 2006–2010 Hummer H3: A Hummer Forums owner with water on both floors of a 2010 H3 had B0790, B2725 and U1017 stored together, plus corrosion on wiring. Members blamed clogged sunroof drains. Read the full answer · Source
What it means: On GM trucks such as the Hummer H3, the transfer case control module (the computer that runs the four-wheel-drive system) sees the wrong voltage on the circuit for the transfer case Neutral indicator light. It usually points to wiring, a connector, or the 4WD selector switch.
Severity: Medium. Safe to drive? Usually yes on the road, but the Service 4WD light stays on and four-wheel-drive shifting may not work correctly. Get it checked before you need 4WD.
DIY or shop?
Finding and fixing a water leak and cleaning corroded connectors is DIY for handy owners. Circuit testing and module replacement are shop jobs.
Before you replace parts
- Read all stored codes and freeze-frame data, not just this one.
- Check your VIN for recalls, service bulletins and extended coverage.
- Inspect wiring and connectors for the related sensor or part before buying parts.
- Clear the code only after a repair, then confirm it stays off.
Safety / mechanic note
Verify with a mechanic. Do not count on 4WD working until this is fixed. A code points to a circuit or system, not always a specific part.