What it means
The control circuit for pressure control solenoid S is reporting a high electrical condition.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Pressure control solenoid S is an electrically operated valve that helps regulate transmission hydraulic pressure. The transmission control module sets P27D8 when it detects an abnormally high electrical condition in the solenoid S control circuit, which may result from a short to battery voltage, an open coil, or poor connector contact.
Common causes
Most likely first.
- Control wire shorted to B+
- Open solenoid coil
- Connector pins corroded - high contact resistance
Symptoms
- Transmission warning light may illuminate
- Harsh or delayed shifting
- Transmission may enter limp mode
How to diagnose it
- Record freeze-frame and live transmission data before clearing P27D8 to see when the high circuit condition occurs.
- Inspect the solenoid S connector and harness for corrosion, loose or pushed-back terminals, and wiring damaged against a power source.
- With power isolated as specified by the manufacturer, test the solenoid S control wire for a short to battery voltage.
- Measure pressure control solenoid S coil resistance and compare it with the manufacturer's specification to check for an open coil.
- If the wire and coil pass, test connector contact and the TCM output circuit using the manufacturer's procedure.
Common fixes
- Repair wiring where the solenoid S control circuit is shorted to battery voltage.
- Repair corroded, loose, or damaged terminals at the solenoid S connector.
- Replace pressure control solenoid S if its coil is open or outside specification.
- Repair the TCM control circuit if testing identifies a fault there.
Can I keep driving?
Avoid towing and hard acceleration, and limit driving because shifting may become harsh or the transmission may enter limp mode. Stop if it slips or loses drive to reduce the risk of further transmission damage.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.