What it means
The TCM detects an electrical fault on transmission pressure control solenoid M. Hydraulic pressure cannot be modulated as expected, causing harsh or slipping shifts.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Pressure control solenoid M is an electrically controlled valve that lets the TCM regulate pressure in a transmission circuit. This electrical fault sets when the TCM detects a problem in solenoid M's electrical operation, so it may be unable to control that circuit's pressure reliably.
Common causes
Most likely first.
- Internal solenoid fault
- Wiring or connector fault
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Read all transmission codes and freeze-frame data, then check whether the fault appears with a particular solenoid M command or operating condition.
- Inspect solenoid M's connector and harness for loose or pushed-back pins, corrosion, fluid intrusion, or chafing.
- Check the solenoid M circuit for continuity, shorts, and power or ground faults using the vehicle's wiring diagram and manufacturer's specification.
- Measure solenoid M coil resistance and compare it with the manufacturer's specification to identify an internal coil fault.
- If the wiring and solenoid pass their checks, verify TCM control and output with the specified diagnostic procedure.
Common fixes
- Reconnect or repair a loose, corroded, or damaged solenoid M connector.
- Repair an open, shorted, or chafed section of solenoid M wiring.
- Replace pressure control solenoid M if its coil fails the specified electrical test.
- Repair the TCM output circuit only if testing isolates the fault to the module.
Can I keep driving?
If shifts are normal, drive only as needed for prompt diagnosis and avoid towing or heavy acceleration. Stop driving if the transmission slips, loses drive, or enters limp mode, since poor pressure control can worsen internal 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.