Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P1566 (42): Motor Commutation Signal Problem: General Description
The motor control module (MCM) detects rotor polar position based on the Low/High combinations of three commutation sensors signals (CMA, CMB, CMC) to supply power to the motor. Each commutation sensor outputs six pulsing signals for each motor revolution, and each signal (CMA, CMB, CMC) phase differs by 20 degrees. The Low/High combination of the signals and its transition state follows a specific pattern, and they are considered abnormal when they do not agree. Normally, the transition state of CMA, CMB, and CMC is synchronized if it follows this pattern:
[L:L:H]→[H:L:H]→[H:L:L]→[H:H:L]→[L:H:L]→[L:H:H]→[L:L:H]→ . . . (H represents High, L represents Low)
If the MCM detects abnormalities a specific number of times within a set duration, it determines the commutation sensor signal is faulty and stores a DTC.
| Execution | Continuous |
| Sequence | None |
| Duration | 0.5 seconds or more |
| DTC Type | One drive cycle, MIL ON, IMA system indicator ON |
| Condition | Minimum | Maximum |
|---|---|---|
| MCM power-supply voltage | 7.0 V | - |
| Motor speed | 500 rpm | - |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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