Trane
E1.x
LockoutPolarity / line / ground family (door-card confirm)
Line polarity, missing ground, or IFC power-quality family. Read the exact E1 decimal on THIS door card / service facts — do not invent a title.
Walk E1.x in Diagnose
2 plates — walk the one on the cabinet
First check
1 Measure µA while it is running
Do not clean first and guess. Series-µA the rod on Trane S8V2 during a call. Falling µA is oxide, ground, or a dying flame. A hard drop is often the pressure switch or limit opening, not the rod. L1/N at the IFC, not just the disconnect.
Expect: Flame: µA per S9V2 service facts.
The rest of the walkthrough is Diagnose.
On the plates
- L1/N at the IFC, not just the disconnect.
- Door switch, 24 V secondary, chassis ground to burner box.
- Twinned or generator jobs — polarity flips after a transfer switch.