What this code means
B1386 may indicate that the power tailgate control unit is not seeing the rotation sensor phase A input change as expected compared with phase B.
What the vehicle may do
- The power tailgate may not power open or close correctly.
- The tailgate may stop during movement or operate inconsistently.
- The system may fall back to limited or manual tailgate operation.
Possible fault areas
- Possible drive unit or rotation sensor signal concern.
- Possible open, short, connector, or wiring issue in the related tailgate circuits.
- Possible power tailgate control unit concern after the related checks pass.
Diagnostic path
Opening context
On this Honda CR-V, B1386 is a power tailgate control unit code. In plain language, the control unit may be seeing the rotation sensor phase A signal not change the way it should compared with phase B. The tailgate may refuse to power open or close, may stop during travel, or may act inconsistently. Possible fault areas can include the drive unit, the rotation sensor signal and feed circuits, connector or wiring issues, or the power tailgate control unit after the rest of the checks pass. Before diving in, start with the basic system checks and follow a structured diagnostic approach. If other codes are present, check what they mean first. And if the motor does not operate at all, do the motor test first.
Reproduce the concern
Begin by reproducing the power tailgate operation. Open the tailgate with the tailgate outer handle switch. Then close the tailgate automatically using the keyless remote or the power tailgate inside switch. This gives you the operating condition for the code before you move into circuit testing.
Check the drive unit signal
Next, move to the power tailgate drive unit inspection. Disconnect power tailgate drive unit connector B, the 6-pin connector. With the connector disconnected, inspect the power tailgate control unit output signal at IG Mode with the signal commanded ON. Normal is About 5 V. There is no direct standalone test for the drive unit itself in this path, so the diagnosis works through the related circuits and outputs. If this output signal is normal, the diagnostic result points to a problem with the power tailgate drive unit, assuming the external circuit is normal. If it is abnormal, keep going because the problem is in another related area.
Check the SENA and SVCC circuits
Now check the PTG/PTL_SENA and PTG/PTL_SVCC circuits. Disconnect power tailgate control unit connector A, the 24-pin connector, and also disconnect power tailgate drive unit connector B, the 6-pin connector. For the PTG/PTL_SENA open-wire check, IG Mode is OFF, and the normal condition is: There is less than 1 Ω. The exact terminals must be positively identified before connecting the meter. If the connector view or terminal path is not clear, pause, recheck the earlier diagnostic path, and avoid guessing.
Check for shorts to ground
After the open-wire check, inspect the short-to-ground conditions as needed. With IG Mode OFF, the PTG/PTL_SENA short-to-ground check is normal when: There is more than 1 MΩ. The PTG/PTL_SVCC short-to-ground check is also normal when: There is more than 1 MΩ. If either circuit check is abnormal, the diagnostic result is a problem in the circuit.
Control unit decision
If the drive unit signal inspection and the SENA and SVCC circuit inspections all show normal conditions, the remaining diagnostic result points to a problem with the power tailgate control unit. Do not jump to that conclusion early. Let the signal check and circuit checks lead you there.
Verification and takeaway
Keep verification separate from the testing. After the fault area has been corrected, go back to the same power tailgate operation check: open it with the outer handle switch, then close it automatically with the keyless remote or inside switch, and confirm the B1386 concern does not return. The key on this one is simple: prove the drive signal, prove the SENA and SVCC circuits, and only then make the control unit call. For more diagnostic training, visit stepdiagnostics.com.
Final check
Prove the drive signal and related circuits before making a control unit decision.
For more guided automotive diagnostics, visit STEP Diagnostics.
