What it means
The control circuit for pressure control solenoid S is reporting a low 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 P27D7 when it detects an abnormally low electrical condition in the solenoid S control circuit, which can result from a short to ground, an internally shorted coil, or poor connector contact.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in 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 P27D7 to identify when the low circuit condition occurs.
- Inspect the solenoid S connector and harness for corrosion, pin damage, or wiring rubbed through to ground.
- With power isolated as specified by the manufacturer, check the solenoid S control wire for a short to ground.
- Measure pressure control solenoid S coil resistance and compare it with the manufacturer's specification to check for an internal short.
- 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 wire is shorted to ground.
- Clean or repair corroded solenoid S connector terminals and restore a secure contact.
- Replace pressure control solenoid S if its coil is shorted or out of specification.
- Repair the TCM control circuit if testing confirms a fault there.
Can I keep driving?
Keep driving to a minimum and avoid towing or hard acceleration because the transmission may shift harshly or enter limp mode. Stop if it slips or loses drive; continued use can worsen 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.