P1942

Code

Generic P — Powertrain

Torque Converter Clutch Solenoid Circuit Malfunction

Brand: Generic

Type: P — Powertrain

Views: UK: 17 EN: 16 RU: 16

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in the TCC solenoid wiring (broken conductor, pinched harness)
Poor or corroded connector at the solenoid or module
Failed TCC solenoid (internal short or open)
Faulty ground or fused power feed to the solenoid circuit
Low or contaminated transmission fluid causing abnormal pressures
Faulty TCM/PCM or internal driver transistor failure

Symptoms

Transmission does not lock torque converter (slips) or fails to unlock
Illuminated Check Engine or transmission warning light
Poor fuel economy and reduced highway response
Transmission shudder, harsh engagement, or unusual shift feel
Possible limp-home/derate mode with limited shift range

What to check

Retrieve freeze-frame and live data with a scan tool; note TCC requested vs actual status
Visually inspect TCC solenoid connector and wiring for damage, corrosion, or pin push-out
Check transmission fluid level and condition (color, smell, contamination)
Measure supply voltage to the solenoid connector (key ON engine OFF)
Measure resistance of the TCC solenoid (compare to spec) and check continuity to module
Backprobe TCM/PCM output while commanding TCC on/off and observe voltage/duty cycle

Signal parameters

TCC solenoid resistance: typically ~8–40 Ω depending on vehicle (consult OEM spec)
Supply voltage: ~12 V (key ON) to the harness feed; 0 V when grounded
Control signal: PWM duty cycle 0–100% or switched 0/12 V depending on manufacturer
Current draw: often
Expected response: commanded lockup indicated in live data and torque converter speed change when applied

Diagnostic algorithm

Connect a professional scan tool. Read and record DTC(s), freeze frame, and live data (TCC requested/actual, shift status, engine rpm, vehicle speed).
Clear codes and attempt to reproduce. Note when the code returns and driving conditions.
Perform a visual inspection of the transmission harness, connector, and solenoid for damage, corrosion, or fluid intrusion.
Check transmission fluid level and condition; correct low or contaminated fluid before further testing.
With ignition ON (engine OFF), check for battery voltage at the solenoid power pin and a solid ground reference at the ground pin. Backprobe harness—do not disconnect connectors initially.
Measure solenoid coil resistance at the connector and compare to manufacturer specification. Infinite or shorted reading indicates a faulty solenoid or wiring.
Command the TCC ON/OFF with the scan tool and observe control voltage or PWM at the solenoid connector. Verify that the module is issuing the expected signal.
If the module commands the solenoid but the solenoid does not respond and coil resistance is within spec, check wiring continuity and for shorts to ground/voltage between the module and solenoid.
If wiring and solenoid are good but no command is present, suspect a TCM/PCM driver fault—verify power and grounds to the module and related fuses. Consider module bench testing or replacement per OEM guidance.
If electrical tests pass but lockup still fails, inspect the valve body/hydraulic circuit and pressure regulation; perform pressure tests per service manual.
After repair or replacement, clear codes and perform a road test while monitoring live data to confirm proper TCC operation and that the code does not return.

Likely causes

Damaged wiring or connector to the TCC solenoid (most common)
Failed TCC solenoid
Faulty power/ground (blown fuse, open circuit)
Contaminated fluid or mechanical valve body issue
TCM/PCM output driver fault (least common)

Fault status

⚠️ Status

Electrical fault in the torque converter clutch solenoid circuit detected. The transmission control module is unable to reliably control torque converter lockup; check wiring, connector, solenoid, fluid, and module.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours