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P codepowertrainMedium severity

P0077Intake Valve Control Solenoid Circuit High (Bank 1)

The Bank 1 intake valve control solenoid circuit is reading a higher voltage than expected, usually from a short to battery power.

Definition

P0077 sets when the PCM sees voltage on the Bank 1 intake valve control solenoid circuit above the calibrated threshold, most often from a short to battery voltage or a stuck/failed driver. The PCM turns on the MIL and defaults the variable intake valve system to a fixed position; if the short energizes the solenoid continuously, the cam timing or lift can be held in an aggressive position, causing rough idle, stalling, or poor performance.

Common causes

  • Control wire shorted to battery voltage (chafed against a powered circuit)
  • Corrosion or moisture bridging connector terminals to a voltage feed
  • Failed solenoid with internal short to its power feed
  • Damaged harness after collision or rodent activity
  • PCM driver transistor failed shorted
  • Aftermarket wiring or accessory tapping into the circuit incorrectly

Common misdiagnoses

  • Replacing the solenoid when the harness is shorted to a power feed
  • Replacing the PCM without isolating the short in the harness first
  • Performing VVT mechanical repairs for what is an electrical high-circuit fault
  • Swapping cam position sensors that do not share the failed circuit

Troubleshooting steps

  1. 1.Check circuit voltage unplugged

    With the solenoid disconnected and key on, measure the control wire — battery voltage present when the PCM is commanding off indicates a short to power or a failed driver.

  2. 2.Isolate the harness

    Disconnect the PCM connector (key off) and recheck: if voltage on the control wire disappears, the short is inside the PCM; if it remains, it is in the harness.

  3. 3.Inspect for chafe against powered circuits

    Follow the harness bundle and look for melted or rubbed insulation where the solenoid wire crosses ignition or battery feeds.

  4. 4.Test the solenoid

    Measure winding resistance and check for continuity between the winding and its supply terminal beyond spec, which indicates an internal short.

  5. 5.Verify after repair

    Repair the short, clear the DTC, and use bidirectional control to sweep the solenoid while confirming commanded and actual valve control agree.

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