P27D2

Code

Generic P — Powertrain

Pressure Control Solenoid S Stuck On

Brand: Generic

Type: P — Powertrain

Views: UK: 17 EN: 42 RU: 38

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Page language: EN

Causes

Solenoid coil shorted internally or short to battery (continuous power).
Stuck or jammed valve in the valve body (mechanical binding, corrosion, debris).
Contaminated or degraded transmission fluid causing valve sticking.
Poor connector contact, corroded pins, or harness damage causing incorrect signal.
Ground fault or short to power in the solenoid circuit.
Faulty transmission control module (TCM) or powertrain control module (PCM) output.

Symptoms

Harsh, delayed, or erratic shifts; unpredictable transmission behavior.
Transmission may go into limp mode or default gear.
High line pressure or inability to modulate pressure resulting in harsh engagement.
Reduced drivability and possible failure to shift into certain gears.
Transmission fluid contamination, burnt smell, or abnormal fluid color (if mechanical wear present).
Stored transmission-related codes and possibly reduced fuel economy.

What to check

Read trouble codes and freeze-frame data; note engine/transmission conditions when code set.
Scan tool: monitor solenoid S command vs actual status/line pressure and other related solenoid data.
Inspect transmission fluid level/condition and filter for metal or debris.
Visual inspection of wiring harness and connectors for corrosion, damage, chafing, or loose pins.
Back-probe solenoid connector and verify command voltage/pulse and steady-state voltage when ON and OFF.
Measure solenoid coil resistance with ohmmeter and compare to manufacturer spec.

Signal parameters

Coil resistance: manufacturer-specific; commonly in the 10–30 ohm range (measure cold, compare to spec).
Control method: usually switched to ground by the TCM/PCM or switched to battery depending on design.
Command signal: pulse-width modulated (PWM) control; duty cycle varies from 0–100% to control pressure.
Typical PWM frequency: varies by vehicle 20–300 Hz (manufacturer-specific).
When commanded OFF: solenoid circuit should show no drive (open or resting voltage per design) and current draw near zero.
When commanded ON: solenoid current draw increases to the coil's rated current; continuous battery voltage on power-switched designs may indicate a short.

Diagnostic algorithm

Retrieve and record codes, freeze-frame, and live data. Clear codes and attempt to re-create the fault under the same conditions.
Visually inspect transmission fluid level/condition and the external wiring/connectors for the S solenoid. Repair any obvious damage.
With ignition off, disconnect solenoid connector and measure coil resistance across the solenoid pins. Compare to spec. Very low resistance suggests a short; open circuit suggests an open coil.
Reconnect and back-probe connector. With scan tool, command solenoid OFF/ON while monitoring voltage/current and live data. Verify that the TCM is commanding correctly and whether the solenoid actually de-energizes.
Use a lab power supply or bench 12 V to energize the solenoid directly (with it removed from vehicle) to see if the valve is mechanically stuck ON when power removed. Observe movement and check for binding.
Scope the control line while commanding the solenoid to confirm PWM frequency and duty cycle, and check for short-to-power or short-to-ground conditions.
If solenoid electrical tests pass and valve still appears stuck, remove and inspect valve body/solenoid assembly for contamination, wear, or jammed spool. Replace or rebuild as required and clean passages.
If wiring, connector, and solenoid are good, verify TCM output driver using a known-good solenoid or by checking module output with proper test procedures. Replace TCM only after ruling out harness and actuator faults.
After repairs, clear codes and road-test to confirm the issue is resolved and no new codes set. Recheck fluid level and condition if transmission disassembled.

Likely causes

Contaminated fluid or debris causing the solenoid valve to stick in the ON position.
Shorted solenoid coil (electrical short to battery) causing continuous activation.
Connector/terminal corrosion or broken wire causing false ON indication.
Internal valve-body defect or stuck spool valve.
Less likely: failed TCM output transistor (module fault).

Fault status

⚠️ Status

Pressure Control Solenoid S circuit/valve stuck ON — continuous activation detected. Check solenoid, wiring/connectors, transmission fluid/valve body, and control module output.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 4.0 hours