Goodman GMSS960803BN Error Code No LED Signal: No Power
What Does Code No LED Signal Mean?
On the Goodman GMSS960803BN, the single diagnostic LED lives on the Integrated Control Module and is powered by that board. When the module gets no 115-volt line power or no 24-volt control power, there is nothing left to light the LED at all, so "no signal" is really the absence of a code rather than a code you count. That distinction matters, because every other fault on this furnace is read by counting flashes; here you are diagnosing why the board itself is dead.
Goodman lists three failure paths for this state: no 115-volt power reaching the furnace (a tripped breaker or a disconnect switch left off), a blown fuse or breaker, or an internal fault in the control module. The blower-door interlock switch is part of this same circuit. The GMSS960803BN will not energize its board with the lower access panel removed or loose, which is a very common reason a furnace goes completely dark right after someone changes a filter.
Because the module is protected by a 3-amp automotive-style fuse, a dark LED overlaps with the fuse-blown branch of the 6-flash rollout code: a short in the 24-volt circuit can pop that fuse and leave the board unpowered. So if your breaker, disconnect, and door switch all check out and the LED still will not light, the problem has moved past the homeowner-safe checks into blown-fuse or board-fault territory, which is technician work.
What You'll Notice
- The diagnostic LED shows nothing at all — no steady light and no flashing
- The furnace is completely unresponsive: no inducer, no blower, no ignition when the thermostat calls for heat
- The furnace breaker is tripped, or the switch on or near the furnace is in the off position
- The furnace went dead right after the blower-compartment door was opened or a filter was changed
- A thermostat that is powered from the furnace goes blank
Common Causes
How This Is Diagnosed
The cause is isolated from the outside in. First the power feed is confirmed: the dedicated breaker, then the service disconnect switch on or beside the furnace, then the blower-door switch that must be fully depressed by a seated panel. If line power is present at the furnace but the board stays dark, attention moves to the 3-amp control fuse and the low-voltage transformer, and finally to the module itself, since a failed Integrated Control Module cannot light its own LED.
How to Fix It: Restore Power to the Control Module
What You'll Need
Steps
- Turn off power at the breaker and shut off the gas supply Before opening any panel, switch the furnace circuit breaker to OFF and turn the gas shutoff valve to the OFF position (handle perpendicular to the pipe). If you smell gas, leave immediately and call your gas company. Working with power off protects you while you reseat the access panel and switch.
- Check the disconnect switch Many furnaces have a switch that looks like a light switch on or beside the unit. Confirm it is in the ON position — it is easy to bump off during other basement or closet work.
- Reset the circuit breaker At the electrical panel, find the furnace breaker. If it is tripped (sitting between ON and OFF), push it fully to OFF and then back to ON. A breaker that trips again immediately points to a short and is not a homeowner repair.
- Reseat the blower-compartment door and door switch Make sure the lower access panel is fully seated so it presses the door interlock switch. The GMSS960803BN will not power its control board if this switch is not engaged, and a panel that sits slightly ajar is a common reason for a dead LED.
- Restore power and gas, then check the LED Turn the gas valve back ON (handle parallel to the pipe) and switch the breaker to ON. Watch the diagnostic LED through the sight glass — it should light up, either steady on or flashing a code you can then act on.
When to Call a Professional
Contact a licensed HVAC technician if:
- The LED stays completely dark after the breaker, disconnect switch, and blower door are all confirmed good
- The furnace breaker trips again the moment you reset it
- The board's 3-amp fuse is blown (a blown fuse points to a short that must be found first)
- There is a burnt smell around the control module or scorched wiring
- Line power is confirmed at the furnace but the board still will not power up
Frequently Asked Questions
Why is my Goodman GMSS960803BN light completely off?
The Integrated Control Module has lost power. The usual homeowner causes are a tripped breaker, a disconnect switch left off, or a blower door that is not fully closed against its interlock switch. If those are all fine, the board's fuse or the module itself may have failed.
Does the blower door really cut all power to the furnace?
Yes. The lower panel presses a safety interlock switch, and the GMSS960803BN will not energize its control board unless that switch is engaged. A panel left slightly loose after a filter change is a frequent reason the furnace appears completely dead.
The breaker keeps tripping when I reset it — what does that mean?
A breaker that trips instantly on reset indicates an electrical short somewhere in the furnace circuit. Stop resetting it and have a technician or electrician find the fault, since repeated resets can damage wiring.
Can I replace the control board fuse myself?
Replacing the board's 3-amp fuse is board-level work, and a blown fuse means a short already exists — a new fuse will usually blow again until the underlying fault is found and repaired, so this is a job for a technician.
✓ Verified against manufacturer service manual — March 2026