Test KitchenAid Dishwasher Motor Start Capacitor

Which models have one?#

• With a start capacitor: KUDS and KUDL series and early KDTE (pre-2016) — single-phase induction motors that need a capacitive boost to start.
• Without one: KDTE, KDTM, and KDFE from 2016 onward, which use ECM motors with built-in electronic starting.

To check, pull the kick plate and look near the circulation pump motor for a small black cylindrical or oval component about the size of a C-battery with two wires into the motor circuit.

The failure signs#

The motor hums during wash but does not spin, often in a repeating hum-click-silence rhythm as the overload trips and resets. The fill phase works but the wash phase stalls, sometimes with a burning smell from the stalling winding, and the breaker may trip after a few minutes of that cycle.

Before you start#

• Tools: 1/4-inch hex nut driver, a multimeter with a capacitance mode, an insulated screwdriver for discharge, needle-nose pliers, and a Phillips screwdriver.
• Safety: Capacitors store energy even after power is off — you MUST discharge the capacitor before handling it, or risk a painful shock (Step 5). Kill power at the breaker first.

Step by step#

1. Cut power. Switch off the dishwasher's breaker, confirm no display lights, and wait 60 seconds.
2. Remove the kick plate. Take out the two 1/4-inch hex screws at the lower front and pull the panel down and forward.
3. Locate the capacitor. It is the cylindrical or oval black-or-brown component near the circulation pump, usually bracketed to the frame (sometimes on the motor housing), with two wires to the motor start circuit.
4. Record the specs. Note the capacitance in microfarads (uF or MFD — common values run 10-30 MFD) and the voltage rating (typically 250V or 370V AC). The replacement must match both; the wrong capacitance stops the motor starting or overheats it.
5. Discharge it — critical. Lay an insulated screwdriver across both terminals at once; a small spark is the stored charge bleeding off safely. Hold it 2-3 seconds, or for a gentler discharge bridge the terminals with a 20K ohm, 5W resistor, then confirm on the meter (DC volts) that it reads 0V.
6. Disconnect and remove. Pull the wire connectors off the terminals with the pliers, remove the bracket screw, and slide the capacitor out.
7. Test the old one. On capacitance mode, read across the terminals — a good part is within 10% of its marked value (a 15 MFD cap should read about 13.5-16.5). A reading of 0, anything under 50% of rating, or OL means it has failed; with no capacitance mode, a dead cap usually shows fully open or shorted on a resistance test.
8. Install the new capacitor. Mount it in the same bracket, secure the screw, and connect both wires — motor-start capacitors are non-polarized, so either wire goes to either terminal.
9. Test the repair. Restore power and start a cycle; once the fill stops, the pump should spin up smoothly instead of hum-clicking, with the spray arms turning within 5 seconds of the wash phase.

After the swap#

• Still hums and will not start: the motor itself may be gone (seized bearings or a shorted winding) — check motor resistance, roughly 3-10 ohms.
• New capacitor runs hot: the capacitance is likely wrong for your motor — verify the exact match.
• Starts but grinds or squeals: worn motor bearings — the capacitor bought you time, but the motor needs replacing.
• Overload keeps clicking with a good new cap and good motor: the overload protector itself may have failed.

Start capacitor vs run capacitor#

Some older KitchenAid units use both: a start capacitor (high capacitance, energized only at startup through a relay for an initial torque boost, and the more common failure) and a run capacitor (lower capacitance, 5-30 MFD, energized continuously to hold efficiency and phase angle). Most models use only a start capacitor; if yours has both, test each on its own.