Coleman Furnace Steady Off (CP9C Echelon Modulating)
WarningShown as: No LED activity at all on the modulating control board
No 24V power at the modulating control board.
Manual wording: “STEADY OFF - No 24V power to board. Check the 24 volt control circuit fuse on the board. Check the circuit breaker or fuse on the 115 volt supply power to the furnace.”
Documented for: CP9C Echelon modulating furnaces (and the identical TP9C / YP9C / LP9C chassis)
Likely causes, most common first
- Open 24 volt control circuit fuse on the board
- Tripped breaker or blown fuse on the 115 volt supply
- Failed 24 volt transformer
What you can safely check yourself
- Check the furnace breaker in the electrical panel is on
- Check the furnace service switch is on
- Make sure the lower door panel is fully seated
When to call a technician
If power at the breaker and switch is confirmed, the on-board fuse or the transformer has failed and needs a technician - a blown fuse usually means something else shorted.
A Coleman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installation Manual - Residential Gas Furnace with ECM Motor, Models TP9C*C, YP9C*C, CP9C*C, LP9C*C (Up to 98% Modulating Multi-position), 681292-UIM-B-1211 (Johnson Controls Unitary Products (Coleman), CP9C*C Coleman Echelon modulating gas furnace (manual also covers the identical TP9C, YP9C and LP9C chassis)) · checked 2026-08-25