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Error code reference

Dacor Oven Error Code U55

Upper/single latch motor failure

Dacor codesDacor oven codes

Upper/single latch motor failure - power to motor is not present or too low for operation; motor output shorted to 5 volts.

First step from the service manual

Check power output on J17 pins 2 and 4. Replace latch motor mechanism or relay board.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What U55 means on a Dacor oven

The U55 error code on a Dacor oven indicates a latch motor failure on the upper or single oven cavity. Specifically, the control system has detected that the power delivered to the latch motor is either absent or too low to drive the motor through its full range of motion. Additionally, the code can trigger when the motor output circuit is shorted to 5 volts, which is a logic-level voltage rather than the higher operating voltage the motor requires. The latch motor is responsible for engaging and disengaging the door lock mechanism, which is critical during self-clean cycles and for safety interlocks.

The diagnostic entry point for U55 is connector J17 on the relay board, specifically pins 2 and 4. These pins carry the power output to the latch motor. A technician should measure the voltage at these pins while the control is commanding the latch to actuate. If the expected operating voltage is absent or significantly reduced, the fault lies either in the relay board's ability to supply power to that circuit or in a wiring harness issue between the board and the motor. A shorted output to 5 volts suggests a failed driver component on the relay board itself.

The two primary repair paths are replacement of the latch motor mechanism or replacement of the relay board. If voltage at J17 pins 2 and 4 is correct but the motor does not respond, the latch motor assembly is the likely failed component. If voltage is missing or reads an incorrect 5-volt level at those pins under command, the relay board's output driver for that circuit has failed and the board requires replacement.

Source: manufacturer service documentation.

Common causes of U55

  1. 01

    Failed relay board output driver

    Part replacement

    The relay board's driver circuit for J17 pins 2 and 4 can fail internally, resulting in no voltage output or an incorrect 5-volt signal at those pins. Measuring the pin output while commanding the latch confirms this failure.

  2. 02

    Defective latch motor mechanism

    Part replacement

    The latch motor itself can fail due to worn brushes, an open winding, or a seized gear train. If correct voltage is present at J17 pins 2 and 4 but the motor does not actuate, the motor assembly needs replacement.

  3. 03

    Wiring harness damage between relay board and latch motor

    Wiring / connection

    A broken, burned, or corroded wire in the harness connecting J17 to the latch motor can interrupt power delivery. Visually inspect the harness and check continuity on each conductor between the connector and the motor.

  4. 04

    Loose or corroded connector at J17

    Wiring / connection

    A poor connection at the J17 connector on the relay board can cause intermittent or absent voltage to the latch motor. Inspect the connector for corrosion, bent pins, or incomplete seating and reseat or clean as needed.

  5. 05

    Short circuit in the latch motor circuit

    Part replacement

    A short to the 5-volt logic rail within the motor circuit or wiring can pull the output voltage down to an inoperable level. Disconnect the motor and check whether the shorted voltage condition clears at the J17 pins to isolate whether the short is in the motor or the board.

See the test procedure for each cause

Frequently asked questions about U55

What does U55 mean on a Dacor oven?
U55 on a Dacor oven means the upper or single oven latch motor has failed to receive adequate power, or the motor output circuit is shorted to 5 volts. The latch motor controls the door lock used during self-clean cycles. The control detects this condition by monitoring the power output at connector J17 pins 2 and 4 on the relay board. The oven will not allow self-clean operation while this fault is active.
Can I fix the U55 error myself, or do I need a technician?
Some basic checks, such as inspecting connector J17 for loose or corroded pins and examining the wiring harness for visible damage, can be done by a knowledgeable DIYer. However, properly diagnosing whether the relay board or the latch motor assembly is at fault requires a multimeter and the ability to measure voltage at the J17 connector while the control commands the latch. Replacing either the relay board or the latch motor is within reach for experienced DIYers, but working around oven wiring carries electrical risk, so professional service is the safer option if you are not comfortable with these procedures.
Is it safe to use my Dacor oven when it shows the U55 error?
Normal baking and broiling functions may still operate depending on when and how the fault is triggered, but you should avoid running any self-clean cycle while U55 is active. The self-clean cycle relies on the door latch motor to lock the door at high temperatures, and a non-functional latch motor means the door lock safety interlock cannot be confirmed. Running self-clean under these conditions is a safety risk and could cause the oven to reach extreme temperatures with an unlocked door.
Will resetting the oven clear the U55 error code?
A power reset by turning off the circuit breaker for 60 seconds may temporarily clear the code, but it will return as soon as the control attempts to actuate the latch motor again if the underlying fault is not repaired. The U55 code is tied to a hardware failure in the latch motor circuit, so a reset alone does not fix the problem. Repair or replacement of the faulty component is required for a lasting resolution.
How much does it cost to repair a Dacor oven showing U55?
Repair costs depend on which component has failed. A replacement latch motor mechanism typically costs in the range of $50 to $150 for the part alone. A relay board replacement is generally more expensive, often in the $100 to $300 range for the part. Adding professional labor, total repair costs can range from $150 to $500 or more depending on your location and the specific model. Getting a diagnosis first, whether by a technician or by testing the J17 connector yourself, will help avoid replacing the wrong component.

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