What it means
The control circuit for pressure control solenoid T 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 T is an electrically operated valve that helps regulate hydraulic pressure in the transmission. The transmission control module monitors its control circuit and sets P27DF when the circuit voltage or current is lower than expected, which can happen if the wire is grounded or the solenoid coil is internally shorted.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in solenoid coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or transmission warning light
- Harsh or delayed shifts
- Transmission may enter limp mode
- Difficulty changing gears
How to diagnose it
- Record freeze-frame data and check transmission live data for solenoid T commands and related pressure or shift faults to see when the low-circuit condition occurs.
- Inspect solenoid T's transmission connector and harness for fluid intrusion, corrosion, damaged insulation, pin damage, or a wire contacting ground.
- With the circuit safely isolated as specified by the manufacturer, check continuity and shorts to ground in the solenoid T control wire.
- Measure solenoid T coil resistance and compare it with the manufacturer's specification to check for an internal short.
- If the wiring and solenoid test correctly, check the module's driver and connector terminals using the manufacturer's diagnostic procedure.
Common fixes
- Clean and secure corroded or loose solenoid T connector terminals.
- Repair the control wire where it is shorted to ground or damaged.
- Replace pressure control solenoid T if its coil is shorted or out of specification.
- Repair the transmission control module driver only after the circuit and solenoid have been verified.
Can I keep driving?
Avoid driving if shifts are harsh, delayed, slipping, or the transmission enters limp mode; continued driving can worsen transmission damage or leave the vehicle unable to shift reliably. If it shifts normally, limit driving and arrange diagnosis soon.
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.