What does it mean?
P1867 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: A/T TCC Solenoid PWM Circuit High Input (5L40-E) .
Symptoms
- Malfunction indicator lamp on and a stored converter clutch circuit code
- Torque converter never locks up; rpm stays high at steady speeds
- Fuel economy falls and highway cruising feels noisier
- Transmission may hold a fixed gear in default operation
- Fluid temperature warning on vehicles that monitor it
- Occasional harsh shifts because torque converter damping is unavailable
Likely causes
- Open or high-resistance connection in the TCC PWM control circuit
- Solenoid winding open internally so the driver never sees a load
- Backed-out, corroded or loose terminal in the transmission case connector
- Control wire chafed against a permanently powered circuit
- Broken wire inside the transmission where the harness flexes
- Poor module ground raising the reference the driver measures against
- Failed driver stage inside the TCM/PCM
How to fix it
- Note the freeze frame conditions and confirm whether the fault is present now
- Inspect the case connector terminals for tension, corrosion and fluid
- Measure solenoid winding resistance — an infinite reading confirms an open coil
- Check continuity from the module pin to the solenoid pin and perform a voltage-drop test on the feed
- With the key on and the solenoid unplugged, check the control wire for unexpected battery voltage
- Repair the open or shorted harness section and reseat any loose terminals
- Replace the PWM solenoid, then retest; the module is the last item to consider