P27C7

Code

Generic P — Powertrain

Pressure Control Solenoid P Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 29 EN: 56 RU: 35

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Causes

Open or high-resistance wiring in the solenoid control circuit
Short to ground on the solenoid control wire
Faulty pressure control solenoid (coil open or internally damaged)
Faulty transmission control module (TCM/PCM) driver or ground
Poor battery/charging system voltage or blown fuse
Corroded or loose connector/pins at the solenoid or harness

Symptoms

Transmission slipping, harsh or delayed shifts
Limp-in/safe mode transmission behavior
Illuminated MIL/Check Engine light or transmission warning lamp
Stored transmission-related fault codes
Possible transmission pressure-related noise or erratic line pressure

What to check

Read and record freeze-frame data and all related transmission codes
Verify battery voltage is healthy (typically 12.4–14.6 V with engine running)
Visual inspection of solenoid connector and wiring for damage, corrosion, or pin push-out
Backprobe connector and check for presence of battery voltage and control signal
Measure solenoid coil resistance and compare to manufacturer spec
Check for continuity to ground and for short-to-ground on control circuit

Signal parameters

Control method: typically PWM from TCM/PCM (0–100% duty cycle) or switched low-side driver
Expected driver behavior: when OFF, harness may show near battery voltage; when ON, driver pulls circuit toward low (≈0–1 V)
Typical coil resistance: commonly in the 10–50 Ω range (varies by design) — consult vehicle spec
Typical coil current when energized: 0.2–2.0 A depending on solenoid and application
Voltage reference for diagnostics: battery voltage (11–14.6 V) and driver low near 0 V when commanded

Diagnostic algorithm

Retrieve freeze-frame data and confirm P27C7 is current or historic. Check for related codes (other pressure solenoids, powertrain grounds).
Confirm battery/charging voltage. Repair charging/battery issues before further testing.
Visually inspect the solenoid harness and connector. Repair any obvious damage or corrosion.
Backprobe the solenoid connector with ignition ON (engine off). Verify reference power and control/driver voltages per vehicle wiring (battery voltage on power feed, expected voltage on control lead).
Command the solenoid ON and OFF using a manufacturer scan tool (or apply appropriate test signal) and observe the control circuit voltage and duty cycle. Confirm driver pulls circuit low when commanded.
Measure solenoid coil resistance with connector disconnected. Compare to vehicle specification. If open or very high, replace solenoid.
Check continuity from the control module pin to the solenoid connector pin; check for short to ground and short to battery. Repair any wiring faults.
If wiring and solenoid test within spec, test or bench the control module output (per manufacturer procedure). Replace TCM/PCM only after confirming module driver fault.
Clear codes and perform a road test to confirm the issue is resolved and no new related codes set.

Likely causes

Damaged harness insulation with wire chafing to chassis (short to ground)
Connector corrosion or bent/mispositioned terminal at solenoid
Solenoid coil resistance outside specification (open or partially open)
Faulty low-side driver transistor in TCM/PCM
Intermittent ground connection or poor battery voltage under load

Fault status

⚠️ Status

Pressure Control Solenoid P control circuit voltage is lower than expected (low). Possible open, short-to-ground, or driver fault affecting transmission pressure control.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours