OBD-II Code · Transmission
P0743
TCC Circuit Electrical
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$200–$800
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
TCC electrical circuit fault.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Likely causes
- WiringMost common
- Failed solenoid
Read the full diagnostic procedureP0743 is an electrical fault on the torque converter clutch solenoid circuit, meaning the TCM commanded the TCC solenoid and saw open circuit, short…
P0743 is an electrical fault on the torque converter clutch solenoid circuit, meaning the TCM commanded the TCC solenoid and saw open circuit, short to ground, or short to power based on the feedback voltage on the driver.
Cheapest-first ladder
- measure solenoid resistance at the case connector (typical spec 10-15 ohms for PWM TCC, 20-30 ohms for on/off depending on platform) and compare to the FSM; back-probe the TCM-side circuit for continuity and proper ground reference with the connector unplugged; inspect the internal wire harness/pass-through connector inside the pan for fluid-saturated insulation and corroded pins (the #1 root cause on many late-model GM and Ford units); only then condemn the solenoid itself.
- Caveat: do not confuse P0743 (electrical) with P0741 (performance/slip) — they call out different failure modes and a P0743 will not be cured by a torque converter replacement.
Vehicle-specific patterns1996-2005 Chevrolet/GMC trucks with the 4L60E and 4L80E set P0743 from internal harness pass-through connector pin corrosion at case connector D.
- 1996-2005Chevrolet/GMC trucks with the 4L60E and 4L80E set P0743 from internal harness pass-through connector pin corrosion at case connector D.
- 2007-2013Dodge Ram with the 545RFE and 65RFE set P0743 when the internal harness chafes against the valve body.
- 2004-2010Ford F-150 with the 5R110W TorqShift sets P0743 from a failed internal wiring harness.
- 2008-2014Cadillac CTS and 2010-2015 Camaro with the 6L50/6L80 set P0743 alongside a TCC slip code when the TCC PWM solenoid sticks from valve body wear, addressable with a Sonnax TCC regulator valve and sleeve kit.
Estimated repair$180 to $1,400.
Look up another code
P0743 — frequently asked
What does a P0743 code mean?
TCC electrical circuit fault.
What causes a P0743 code?
Common causes: Wiring; Failed solenoid.
What are the symptoms of a P0743 code?
Typical symptoms: Check engine light.
Is it safe to drive with a P0743 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $200-$800.
How do I diagnose a P0743 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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