P27DF

Code

Generic P — Powertrain

Pressure Control Solenoid T Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 17 EN: 25 RU: 21

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Page language: EN

Causes

Damaged or corroded connector or wiring in the solenoid T circuit
Short to ground in the solenoid control wire
Open circuit or high resistance in wiring or connector
Failed pressure control solenoid T (internal short or coil failure)
Poor or missing power feed or ground at TCM
Faulty TCM or internal driver fault

Symptoms

Transmission limp mode or reduced functionality
Delayed, harsh, or incorrect shifting
Gear hunting or inability to hold selected gear
Transmission warning light, MIL or TCM lamp illuminated
Diagnostic trouble codes relating to pressure control or other solenoids

What to check

Read freeze-frame and live data with a scan tool; confirm P27DF and any related codes
Attempt to reproduce condition and note when code sets (key on/engine running, during shift, at idle)
Visually inspect connector, pins and wiring for damage, corrosion, or fluid contamination
Backprobe the solenoid connector with connector mated; check for battery voltage, ground presence and controlled signal while commanding solenoid with a scan tool
Measure coil resistance of solenoid T with the solenoid disconnected from harness and compare to manufacturer spec
Check for continuity to ground and shorts to battery on the control wire

Signal parameters

Typical coil resistance: varies by vehicle (commonly ~10–60 Ω) — verify with factory specification
Expected open-circuit voltage on feed side: ~battery voltage (≈11–14 V) with ignition on
Control signal: TCM typically drives solenoids with a switched ground or PWM; commanded duty cycle 0–100% depending on pressure demand
When driver commands 'off' the control line should not be continuously pulled to ground; when commanded 'on' control line will show switching (PWM) or ground return
A 'low' circuit indication often means measured voltage on control line is very low (close to 0 V) when it should be at or near battery voltage or showing switching — check against vehicle-specific values

Diagnostic algorithm

Read and record all related codes and freeze-frame data. Note operating conditions when code set.
Visually inspect solenoid T connector and wiring for damage, corrosion, fluid intrusion, pin deformation or poor seating. Repair obvious issues.
With harness connected, backprobe the control and feed pins. With ignition ON (engine off), verify feed (battery) voltage at the feed pin and that control pin is not shorted to ground unless commanded.
With a scan tool, command solenoid T ON/OFF while monitoring control pin. Observe voltage behavior (should switch or show PWM when commanded).
Disconnect solenoid at the harness and measure coil resistance across the solenoid terminals. Compare to spec. Infinite or very high resistance = open coil; very low = shorted coil.
Check continuity of the control wire between TCM connector and solenoid connector. Check for shorts to ground or battery with ignition off. Repair any wiring faults.
Verify TCM power and ground circuits and check for proper connector seating. If wiring checks good and replacement solenoid behaves the same, suspect TCM output driver fault.
If wiring and TCM appear good, replace the solenoid. After repair, clear codes and road test to verify normal operation and that P27DF does not return.
If code persists after wiring and component replacements, perform manufacturer-specific TCM tests and consider TCM replacement or reprogramming per service info.

Likely causes

Wiring shorted to ground on solenoid T control circuit
Open/high-resistance connection at solenoid or connector
Failed/shorted pressure control solenoid T
Faulty TCM output driver or poor TCM ground

Fault status

⚠️ Status

Pressure Control Solenoid T control circuit reported low voltage — possible short to ground, open/high resistance, failed solenoid, or TCM driver fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours