UniMac Washer-Extractor Error Code E d 32: Back EMF Error
E d 32 is a back EMF error on a UniMac QN washer-extractor. The drive heard an unexpected voltage from the turning motor and stopped the cycle. Take the machine off power to reset it and call us if the code comes back.
Medium: the drive stops the cycle, and the cause is usually a harness or motor reading rather than a safety hazard.
- Code
- E d 32
- Maker
- UniMac
- Equipment
- Industrial laundry
- Applies to
- CHM1792C family washer-extractor (QN models, 20-100 lb) front-end control
What does UniMac error code E d 32 mean?
When a motor turns, it also acts like a small generator, and the voltage it produces is called back EMF. E d 32 is the back EMF error on a UniMac QN washer-extractor such as the UCA020QN. The drive listens to that returning voltage because it tells the drive how fast the motor is really turning. This time what it heard was unexpected, and the drive stopped the cycle rather than control a motor it could not read.
The odd voltage can come from three places. The motor harness may have a loose pin or worn insulation that distorts the signal. The motor may have windings that produce an odd voltage while turning. The drive board may read the returning voltage incorrectly. A drum that does not turn freely can also make the motor voltage look unexpected. The power needs to be cycled to clear the code, and the display resets once the machine is off power.
Affected models and control systems
E d 32 is listed for the CHM1792C family washer-extractors, the QN models from 20 to 100 lb, with the front-end control and drive board; the manual's example model is the UCA020QN.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- The display shows E d 32 and the cycle stops
- The motor stutters or surges as the drum accelerates
- Rotation sounds uneven before the stop
- The code repeats at the same point in each spin
Possible causes
Listed in UniMac's documentation
- A drum that does not turn freely, so the motor voltage looks unexpected
- A motor harness with a loose pin or worn insulation
- A motor whose windings produce an odd voltage while turning
- A drive board that reads the returning motor voltage incorrectly
Other likely causes — what usually sits behind error code E d 32 on this control. A technician confirms which one it is before any part is replaced.
- Single motor lead whose pin is half out of the connector housing
- Shielding or ground on the motor cable damaged so the signal picks up noise
- One motor winding partly shorted so the three phases are unequal
- Voltage-sensing circuit on the drive drifted with age
Safe checks before calling for service
- Take the machine off power, and the display resets.
- Test by hand, with the power off, whether the empty drum moves freely.
- Do not open panels to touch the harness.
- If E d 32 returns, tell us at which point of the cycle it appeared, and call us, since a motor or drive board may need replacing.
How a technician diagnoses error code E d 32
- Read the code and note where in the spin it appears.
- Lock out the machine and check the drum for drag.
- Inspect the motor harness and pins at both ends.
- Compare the three motor winding resistances.
- Test the drive with a known-good motor or harness before replacing the board.
- Back EMF is judged by measuring motor signals on a running drive, which means live high-voltage work.
- A harness pin problem is invisible without pulling the connector apart.
- Deciding between motor and drive board needs substitution tests with parts on hand.
Technical reference
- Document
- Washer-Extractor Programming CHM1792C_SVG, Part No. F8641001ENR4, Error Codes Table 29 (pp. 100-107)
- Maker documentation
- UniMac owner support
- Edition
- Part No. F8641001ENR4, January 2020
- Models / control
- CHM1792C family washer-extractor (QN models, 20-100 lb) front-end control
- Section
- Error Codes, Table 29, pp. 100-108 (PDF pages equal printed pages)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related UniMac industrial laundry error codes
Is back EMF a sign the motor is generating electricity by mistake?
It is normal for a spinning motor to produce it. The code only means the drive saw a value it did not expect.
Does switching off fix it?
It clears the display. If the harness, motor or board is the cause, E d 32 will return.
Is E d 32 related to E d 34?
Both involve motor behavior, but E d 34 means the rotor is locked, and E d 32 means the signal from a turning motor is wrong.
Need help with UniMac error code E d 32?
A technician confirms the cause on site and gives you the price in writing before any work starts.