What it means
Voltage on the pressure control solenoid M control line is below 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 while monitoring its voltage and operation. This low-circuit fault sets when voltage on solenoid M's control line falls below the expected range, which can happen if the wire is shorted to ground, the coil is internally shorted, or a connection is faulty.
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 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 codes, then check whether the low reading occurs when solenoid M is commanded.
- Inspect solenoid M's connector and harness for chafing to ground, water ingress, corrosion, or pushed-back pins.
- With the circuit monitored using the specified scan-tool or meter procedure, gently move the harness to check whether solenoid M's low-voltage fault changes.
- Check the control wire for a short to ground and inspect connector condition, using the wiring diagram and manufacturer's specification.
- Measure solenoid M coil resistance and compare it with the manufacturer's specification to check for an internal short.
Common fixes
- Repair chafed solenoid M wiring that is contacting ground.
- Clean or replace corroded connector pins and repair failed seals that allowed water intrusion.
- Replace solenoid M if its coil is internally shorted.
- Repair a damaged harness or terminal connection that causes the control-line voltage to remain low.
Can I keep driving?
Limit driving and avoid towing or hard acceleration if shifts are harsh, slipping, or the transmission enters limp mode. A low control-circuit voltage can prevent solenoid M from regulating pressure and may lead to further 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.