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DTC codes / P08xx · Transmission / P08DC

P08DCShift Solenoid K Control Circuit High

P08DC indicates that the transmission control module (TCM) has detected an abnormally high voltage on the control circuit for shift solenoid K, which is one of the solenoids that manages hydraulic pressure for gear shifts. The TCM expects the circuit to pull the voltage low when the solenoid is commanded on, but instead it sees voltage staying near battery positive, indicating an open circuit, a short to power, or a faulty solenoid.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaTransmission

Symptoms you may notice

  • Illumination of the check engine light or transmission warning light, often with no other noticeable symptoms.
  • Harsh or delayed gear shifts, especially when the transmission attempts to engage or disengage the affected gear.
  • The transmission may enter limp mode, sticking in a single gear or refusing to shift.
  • Poor fuel economy or increased engine RPM at highway speeds due to improper shift scheduling.
  • In some cases, the vehicle may fail to move from a stop or may experience slipping during acceleration.

Common causes, most likely first

  1. Faulty shift solenoid K itself, such as an open coil or internal short.
  2. Damaged or corroded wiring harness or connector at the solenoid or TCM.
  3. Open circuit in the control wire between the TCM and the solenoid.
  4. Short to voltage on the control circuit, often due to chafed wiring touching a power source.
  5. Poor ground connection for the solenoid or TCM, causing reference voltage errors.
  6. Failed TCM driver circuit, though this is less common than wiring or solenoid issues.

How to diagnose and fix it

  1. Use a scan tool to verify the code and check for any related transmission codes; record freeze-frame data if available.
  2. Inspect the solenoid connector and wiring for corrosion, loose pins, or physical damage, and repair as needed.
  3. Measure the resistance of shift solenoid K with a multimeter and compare to the manufacturer's specification; replace if out of range.
  4. Check for continuity and short to voltage on the control circuit between the TCM and solenoid, repairing any wiring faults.
  5. Test the TCM ground and power supply circuits to ensure they are within specification.
  6. If all external circuits test good, substitute a known-good solenoid or TCM to isolate the faulty component.
  7. Clear the code and perform a road test to verify the repair and ensure the transmission shifts correctly.

Don't overlook the wiring harness

  • A common oversight is replacing the solenoid without checking the wiring harness for chafing or corrosion, which often causes the high voltage code.
  • The code can be set by a poor ground connection at the transmission case, leading to a false high voltage reading on the control circuit.
  • In some vehicles, a faulty TCM driver may mimic a solenoid failure, so always test the circuit before condemning the solenoid.
  • Intermittent faults may only appear when the transmission is hot or under load, so a wiggle test of the harness while monitoring live data can be revealing.
  • This code does not always mean the solenoid is defective; a short to power elsewhere in the circuit can produce the same symptom.

Can I keep driving with P08DC?

Driving with P08DC is generally not recommended because the transmission may enter limp mode or shift erratically, which can be unsafe in traffic. If you must drive, avoid heavy acceleration and highway speeds, and seek repair as soon as possible.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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