What it means
The TCM detects an open circuit in the control wiring of pressure control solenoid M. No current flows when the solenoid is commanded.
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 receives an electrical control signal from the TCM to regulate transmission pressure. This open-circuit fault sets when the control circuit cannot carry current, such as from a broken wire, an open solenoid coil, or a poor connector pin connection.
Common causes
Most likely first.
- Open in solenoid control wire
- Open solenoid coil
- Pin pushed back out of connector body
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
- Record freeze-frame data and related transmission codes, then check whether solenoid M was commanded when the open-circuit fault was detected.
- Inspect solenoid M's connector for a pushed-back pin, loose fit, corrosion, or fluid intrusion, and inspect the harness for breaks or chafing.
- Check circuit continuity from the TCM to solenoid M using the wiring diagram and the manufacturer's procedure to locate an open wire or terminal.
- Measure solenoid M coil resistance and compare it with the manufacturer's specification to determine whether the coil itself is open.
- If the wiring and coil pass, check the TCM connector and output circuit for an open connection using the specified diagnostic procedure.
Common fixes
- Seat the pushed-back or loose solenoid M connector terminal correctly or replace the damaged terminal.
- Repair a broken or open section of the solenoid M control wire.
- Replace solenoid M if its coil is open.
- Repair a damaged TCM connector or output circuit if testing identifies an open there.
Can I keep driving?
Avoid towing or extended driving if shifts are abnormal or the transmission enters limp mode. With no current reaching solenoid M, pressure control may be lost and continued slipping can damage the transmission.
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.