A control board is usually confirmed as the fault by elimination: the technician proves that power reaches the board, that the part it drives is good and that the wiring between them is intact, and then shows that the board isn't sending the signal it should. You can help by describing everything that's acting oddly, not just the main symptom, and by mentioning any storm, outage or spill.
Before the visit
- •Model and serial number, from the label.
- •All the symptoms. A display that flickers, buttons that don't respond, or several unrelated parts misbehaving all point differently than one dead part.
- •Codes, photographed before any reset.
- •Events, such as a lightning storm, a power outage or water spilled on the controls.
- •Access to the appliance and its outlet or breaker.
Safe pre-checks:
- Turn the appliance off at the breaker for a minute and restore power, after you've photographed any code.
- Make sure the controls are dry and that no control lock is on.
- Don't remove control panels yourself. Boards sit next to line-voltage wiring.
The checks, in the usual order
| Step | What's tested | What it rules in or out |
|---|---|---|
| 1 | Supply voltage at the outlet and into the board | A board with poor power can't be judged |
| 2 | Stored codes and any self-test result | Separates a control failure from an outside fault, where the model reports it |
| 3 | The part the board drives, tested on its own | A failed part can look like a board that won't run it |
| 4 | Wiring harness continuity and connectors | An open wire or burned connector can mimic a board fault |
| 5 | Board output when the part is commanded in service mode | No output with good input points at the board |
| 6 | A close look at the board | Scorching, corrosion or moisture supports the finding |
| 7 | Setup or calibration after a board is replaced | Some models need it before they run correctly |
Manufacturers write this order into their troubleshooting. In Whirlpool's tech sheet for one top-load washer (W11448643), if the lid lock switch readings are wrong the lid lock is replaced, and if they're correct the main control is replaced. Its tech sheet for a front-load washer (W10254472) checks the door lock's readings, then harness continuity, then the lock mechanism, and only then the control. Whirlpool's ADA dishwasher service manual does the same with the heater: if the service-mode heat step runs and no line voltage reaches a good heater, the control board is replaced.
Tools you may see
- •Service mode, to command each output.
- •Multimeter, for supply voltage, part resistance and wiring continuity.
- •Wiring diagram, from the model's tech sheet.
- •Antistatic wrist strap. The washer tech sheet warns that as little as 10 volts of static can destroy, damage or weaken the main control.
Questions you'll probably be asked
- •Is more than one function acting up?
- •Did it start after a storm, outage or surge?
- •Does the display flicker, freeze or show random codes?
- •Has liquid reached the control panel?
- •Was a board replaced before, and did the problem come back?
- •Is the problem constant or does it come and go?
What the findings usually mean
- •Low or missing supply voltage: the household circuit, not the board.
- •The part tests bad: the part is the fault, even if the board was suspected.
- •An open wire or burned connector: the harness, which can damage a board if it's left in place.
- •Good input, good part, good wiring, no output: the board.
- •Random behavior across several systems after a surge: the board is a strong suspect, but still confirmed by the same tests.
- •A board was replaced and the problem returned: an earlier step was likely missed, so the part and wiring are retested.
On the washer above, the tech sheet calls for a calibration after the main control is replaced. For how output tests are run, see how appliance service and diagnostic modes work; for one example of this order in practice, see what a technician checks when a front-load washer door won't lock.
Sources
- •Tech Sheet W11448643 (top-load washer), Whirlpool
- •Tech Sheet W10254472 (front-load washer), Whirlpool
- •Service Manual, Whirlpool 18" and 24" ADA Built-In Dishwashers (W11187658), Whirlpool
Good to know: A control board is a conclusion, reached after the power, the part and the wiring have each been proven good.
TrueFix San Antonio serves homes from downtown San Antonio to the surrounding suburbs; call (210) 401-3007 to book a diagnosis.