How to use: Click pins in the connector to select them. Type a label (what it does) and hit SAVE. Combos persist in your browser (localStorage). Click status pills to toggle ✓ verified, ✗ fails, or ? unknown. Edit pin names inline as you probe the PCB.
Connector // click pins to select
Tip: the default pin names are typical HJH5 guesses. Probe each pad with a meter and rename as you confirm. The pin order here is a visual layout — it does not imply the actual DIN keying. Match numbers to your PCB silkscreen.
1 — Pigtail isn't actually making contact with the PCB pad
Button dome still works (it bridges through its own carbon contact), but your tap wire is floating. Check: meter in continuity mode — probe from the far end of the Yellow pigtail to the HU pad on the PCB. Beep = good. Silence = re-solder.
Most common cause of this exact symptom. Check first.
2 — Tapped on the wrong side of the SMD button
Each button has 2 pads. One is the signal trace, the other is already ground. If Yellow is on the GND side, shorting to White (also GND) does nothing. Check: press the physical button while metering each button pad to GND — the one that momentarily changes state is the signal side. That's where your pigtail must be.
3 — Relay contact isn't closing (LED lies)
Cheap relays sometimes fire the coil (LED on) but the contact is fused open. Check: meter across NO1 and COM1 while triggering from Tuya. Should read ~0Ω when on, OL when off. If never closes → dead relay.
4 — Relay is latching instead of momentary
HJH5 controllers debounce. If the relay closes and stays closed, the controller sees one press and ignores it forever. Fix: Smart Life → device → Relay Status or Power-On Behavior → set to Momentary or Inching with pulse of 500ms–1s.
Second most common cause. If the bed moved once and then stopped responding, this is it.
5 — Active-HIGH controller (inverted logic)
Rare on HJH5 but possible: buttons pull signal up to VDD, not down to GND. Your relay shorts Yellow to White — if logic is inverted that does nothing. Test: briefly jumper Yellow to Red (VDD) with a tweezer. If head moves, your COM wiring is wrong and should move to VDD (Red) instead of GND (White).
6 — Ground reference mismatch
Relay powered by its own 5V USB brick with no shared ground to the bed controller means NO1–COM1 closure may not register as a real button press. Fix: make sure the White pigtail truly reaches the controller GND plane (not a floating pad), and that the relay's own GND is not isolated in a weird way. A bench test: connect relay GND to bed controller GND with a temporary wire and retest.
7 — Use the combo lab above to prove the pair manually
The fastest diagnostic: take a short jumper wire (or tweezer tip) and bridge the two pins your UP combo says should fire. If the bed moves with a manual jumper but doesn't move when the relay closes the same pair, the pin pair is correct and the relay is the problem (see #1–#4). If the jumper doesn't move the bed either, the pin pair is wrong — try other combos and update this lab.
This is the whole point of this page. Log what works, log what fails, narrow it down.
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