P27D8

Code

Generic P — Powertrain

Pressure Control Solenoid S Control Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 39 RU: 24

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Page language: EN

Causes

Short to constant battery/ignition voltage on the solenoid control wire
Corroded, loose, or damaged connector or terminals at the solenoid
Open or high-resistance wiring between solenoid and controller
Failed pressure control solenoid (internal short or internal electronics fault)
Faulty transmission control module (driver transistor stuck high)
Water intrusion, PCM/solenoid harness damage or chafing

Symptoms

Malfunction Indicator Lamp (MIL) or transmission warning lamp illuminated
Transmission may stay in limp mode or default gear
Harsh, delayed, or erratic shifts
Reduced transmission performance or unwillingness to shift
Possible transmission slipping or abnormal noise during gear changes

What to check

Read and record freeze frame and all stored codes; check for related transmission codes
Visually inspect solenoid connector, pins and wiring for corrosion, pushed-out terminals, damage, or contamination
Backprobe the solenoid control connector and measure voltage with key ON and while commanding solenoid ON/OFF with a scan tool
Measure solenoid coil resistance at the connector (compare to service spec) to check for open or shorted coil
Check for short to battery: disconnect solenoid and verify whether high voltage is present on the control circuit
Inspect harness routing for chafing, pinched areas or contact with hot components

Signal parameters

Expected supply voltage at harness (key ON): ~11–14 V (vehicle battery voltage) at the solenoid supply pin if present
Typical solenoid coil resistance: usually in the approximate range 6–40 ohms (refer to OEM spec for exact value)
Driver low when commanded ON: PCM/TCM should pull control circuit near 0–1.0 V (ground side drive)
Driver released when OFF: control circuit should be high-impedance or near supply voltage (about battery voltage)
High-circuit fault: control wire measures higher-than-expected voltage when it should be low, or measures battery voltage with driver commanded OFF indicating possible short to battery

Diagnostic algorithm

Retrieve freeze frame and all stored codes; note conditions when code set (temp, rpm, gear).
Visually inspect connectors and wiring for the solenoid S and related circuits. Repair any obvious damage before further testing.
With ignition ON (engine OFF), backprobe the solenoid connector. Verify supply pin battery voltage and control pin voltage while commanding the solenoid OFF and ON with a capable scan tool.
Disconnect the solenoid harness and check if the 'high' voltage is still present on the control circuit. If high voltage remains with solenoid disconnected, suspect wiring short to battery or PCM driver issue.
Measure solenoid coil resistance at the solenoid. Replace solenoid if coil is open, shorted or out of spec.
Check for continuity and shorts between control wire and battery, chassis ground, and other circuits. Repair harness faults (splice, replace wire, secure routing) as needed.
After repairs, clear codes and perform a road/shift test to verify proper operation. Re-scan to confirm code does not return.
If wiring and solenoid test good but fault returns, follow vehicle-specific procedures to test or replace the TCM/PCM or have it bench-tested by a qualified specialist.

Likely causes

Short to battery/ignition voltage on the solenoid control circuit
Damaged connector or harness near the solenoid
Failed solenoid coil or internal electronics
Faulty TCM/PCM driver (less common)

Fault status

⚠️ Status

Transmission pressure control solenoid S circuit voltage above expected threshold. Controller detected a high control-circuit condition and stored DTC P27D8. Inspection of wiring, connector, solenoid, and control module recommended.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours