Ch 13Note
What if — first-start failures and what they actually mean¶
Note · Chapter 13 — Initial startup
| Symptom | Most likely cause | Fix |
|---|---|---|
| A temperature climbs with nothing commanded | Heater energised through a wiring fault | Cut power at the switch. Back to Ch 10 — do not "just watch it" |
| Thermistor reads a wild or jumping value | Crimp, or a PH2.0 housing half-seated / in the wrong header | Re-seat, check continuity. Rev D+: uses PH2.0, not the guide's XH2.5 |
| Hotend heats when you command the bed (or vice versa) | Thermistor pair or heater pair swapped | Swap at the board, power off first |
| Bed does not heat, SSR LED on | Fault on the mains side of the SSR | Check LOAD 1 / LOAD 2 and the bed L/N |
| Bed does not heat, SSR LED off | Control polarity reversed | Leviathan + → SSR INPUT 3, − → INPUT 4 |
| A fan never starts | Wrong port, wrong voltage jumper, or the keyed 2×5 (10-pin) toolhead header seated backwards | Check the port against the config; Rev D+: header is keyed — if it will not drop in, it is backwards. BLDC fans do not spin backwards on reversed polarity, they do nothing or burn out |
The wrong toolhead fan answers — the top (5015) fan follows the hotend, the bottom (4010) fan follows M106 |
Fan adapter HEF/PCF assignment is the reverse of the config (the Ch 08 Step 08.46 source conflict) | Swap pin: nhk:PD0 and pin: nhk:PA15 between [heater_fan hotend_fan] and [fan], RESTART, re-run 13.9–13.10. Do not re-plug or re-crimp |
STEPPER_BUZZ moves nothing |
enable_pin/step_pin, or no driver power |
Check the pins; check the HV/24 V rail |
STEPPER_BUZZ buzzes without travelling 1 mm |
Stepper coil pairs transposed in the connector | Re-pin the connector so each coil is a pair. Power off first |
| A motor moves the wrong way | dir_pin polarity |
Add or remove ! on that stepper's dir_pin, RESTART, re-buzz |
| The wrong motor answers | Motors in the wrong ports | Power off, move the connector, power on. Never hot-swap a stepper |
G28 X sends the gantry down first |
Z stepper directions reversed | Fix Z dir_pins before touching A/B |
| X and Y both move, but the toolhead goes diagonally / the wrong axis | A and B swapped, or one inverted | Read the V2 configuration chart; upper block → invert a dir_pin; lower (orange) block → physically swap A and B |
An endstop reads TRIGGERED untouched |
Wiring, not polarity | Stock Voron endstops are N.C. to ground — a needed ! usually means a wiring fault. Fix the wiring |
| Endstop unreachable by the toolhead | Rubber rail stopper still on the rail, or racked gantry | Remove stoppers; then Ch 06b |
G28 → Move out of range: -10.000 -10.000 … |
[safe_z_home] home_xy_position still the -10,-10 placeholder |
Step 13.26 |
| Homing overshoots into the frame, or stops short | The wrong build-size pair is uncommented (there is no default — with all three commented Klipper does not start) | Step 13.5: the Moonraker query must show 350.0, 350.0, 330.0 |
A G28 X or G28 Y stalls the Z motors against the frame, or drops the nozzle onto the bed |
Gantry parked at its top stop (or a reversed Z dir_pin) — every homing move before Z is homed lifts 10 mm from wherever the gantry is |
Step 13.17's first Do line: hand under the gantry, release the motors as it says, lower the gantry to a third of its travel; Step 13.16 for the dir_pin |
QUERY_PROBE stuck open or stuck TRIGGERED |
Ground/signal/24 V, wrong [probe] pin, or a voltage-select jumper |
Check wiring first, then pin: !nhk:PC15 |
| Probe triggers too early (nozzle still several mm up at trigger, or the probe grazes the plate) | Probe mounted too low in the retainer bracket | Raise it in the bracket. It must clear the plate and any clips at every mesh point |
| Probe triggers too late (nozzle nearly touching at trigger) | Probe mounted too high in the retainer bracket, or fibreglass tape on the sensing face | Lower the probe in the bracket so it triggers with the nozzle ~2 mm above the plate; strip tape from the back and bottom — front and sides only |
PROBE_ACCURACY σ high but stable |
Probe mount, cable strain, or [probe] speed too fast |
Check the bracket is tight; try a lower speed |
PROBE_ACCURACY values trending one way |
Thermal, or mechanical: Z pulley grub screws, uneven Z belts | Soak longer; then check all four Z belts and the pulley set screws |
Probe samples exceed samples_tolerance |
Same causes; samples_tolerance: 0.006 is tight by design |
Fix the cause, do not widen the tolerance |
| Bed and hotend switched themselves off mid-soak, motors released (gantry may have dropped) | [idle_timeout] timeout: 1800 in the LDO config — 30 min without a move runs TURN_OFF_HEATERS + M84; not a fault |
SET_IDLE_TIMEOUT TIMEOUT=7200 before every soak (Steps 13.31, 13.35, Ch 14 Steps 14.3, 14.8); re-heat, G28, repeat the soak |
QGL does not converge — Probed points range stalls or grows |
Gantry racking | Step 13.34 → Ch 06b (cold squaring, provisional A/B tension), then Step 13.35 re-QGL |
A move will not stop when you send RESTART |
RESTART queues behind the running move; only a line that is exactly M112 goes round it — Mainsail sends that as its emergency-stop call |
Send M112 alone on the line (or Mainsail's red Emergency Stop), then FIRMWARE_RESTART |
QGL: Retries aborting: Probed points range is increasing. Possibly Z motor numbering is wrong |
Z motors on the wrong drivers | Recheck the Z map: Z0 front-left → STEPPER-0, Z1 rear-left → -1, Z2 rear-right → -2, Z3 front-right → -3 |
QGL: Aborting quad_gantry_level required adjustment … is greater than max_adjust |
Gantry too far out of level to correct in software | M84 with a hand under the gantry (it sinks when the Z motors release), level the gantry by hand against the frame, G28, retry |
| QGL "out of bounds" / cannot reach the probe point | Gantry far from level, or wrong gantry_corners |
FIRMWARE_RESTART with a hand under the gantry (it sinks when the Z motors release), level the gantry by hand against the frame, G28, retry; confirm the 350 corners -60,-10 / 410,420 |
Unknown command:"BED_MESH_CLEAR" at the end of a print |
No [bed_mesh] section |
Step 13.38. It is a warning, not a failure — but you have no mesh |
| First layer is right at the front and wrong at the back (or similar) | Meshed before QGL, or mesh taken cold | Re-run: G28 → QUAD_GANTRY_LEVEL → G28 → BED_MESH_CALIBRATE, hot |