Error code reference
Trane Furnace Error Code 8 Flash
Low flame sense signal
Low flame sense signal - flame sense current is less than 1 micro-amp DC but still strong enough to allow operation.
First step from the service manual
Disconnect power; connect voltmeter leads in series with flame sensor set on DC micro-amp scale; verify flame sensor is correctly located.
The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.
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- Step-by-step tests with expected resistance, voltage, and continuity values
- Wiring diagram references and connector pinouts from the OEM service manual
- Verified part numbers when replacement is required
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