What it means
Voltage on the pressure control solenoid M control line is above the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The TCM controls pressure control solenoid M through an electrical circuit and monitors the control-line voltage. This high-circuit fault sets when that voltage rises above the expected range, which can result from a short to battery voltage, an open solenoid coil, or a poor connection.
Common causes
Most likely first.
- Control wire shorted to B+
- Open solenoid coil
- Connector pins corroded - high contact resistance
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
- Save freeze-frame data and related codes, then check whether the high-voltage reading occurs while solenoid M is commanded.
- Inspect solenoid M's connector and harness for chafing against a power wire, corrosion, water intrusion, or loose and pushed-back pins.
- Check the control wire for a short to battery voltage using the wiring diagram and manufacturer's specified procedure.
- Measure solenoid M coil resistance and compare it with the manufacturer's specification to check for an open coil.
- If the harness and coil pass, verify the TCM output circuit and connector using the specified diagnostic procedure.
Common fixes
- Repair solenoid M control wiring that is shorted to battery voltage.
- Clean or replace corroded or loose connector terminals and repair damaged seals.
- Replace solenoid M if its coil is open.
- Repair a damaged TCM connector or output circuit if testing identifies the source of the high voltage.
Can I keep driving?
Avoid towing and hard acceleration if shifts are abnormal, the transmission slips, or limp mode engages. The high circuit fault can stop solenoid M from controlling pressure correctly and continued driving may 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.