What does P1779 mean on a Chevy?

P1779. Engine Torque Delivered to TCM Signal. Applies to Silverado, Sierra, Suburban, Yukon XL.

What causes P1779 on a Chevy?

Open or short in the engine torque signal circuit between ECM and TCM Corroded ECM or TCM connectors Faulty engine control module torque output driver Aftermarket engine tuning corrupting the torque signal Faulty transmission control module

How do I fix P1779 on a Chevy?

Monitor delivered engine torque signal with a Tech2 or GDS2 scan tool Inspect ECM and TCM connectors for corrosion or loose pins Test the torque signal circuits for opens, shorts to ground, and shorts to voltage Return any aftermarket tune to stock and retest if applicable Replace the faulty module only after all circuit tests pass

Code

P1779

Engine Torque Delivered to TCM Signal

Category: Powertrain - Transmission
Severity: Check Engine Light
Applies to: Silverado, Sierra, Suburban, Yukon XL
Related: No single generic twin. See OBD Codes List

What it means

P1779. Engine Torque Delivered to TCM Signal. This Chevy-enhanced code applies to Silverado, Sierra, Suburban, Yukon XL.

Findings, check these first

Open or short in the engine torque signal circuit between ECM and TCM
Corroded ECM or TCM connectors
Faulty engine control module torque output driver
Aftermarket engine tuning corrupting the torque signal
Faulty transmission control module

Standard procedure

Monitor delivered engine torque signal with a Tech2 or GDS2 scan tool
Inspect ECM and TCM connectors for corrosion or loose pins
Test the torque signal circuits for opens, shorts to ground, and shorts to voltage
Return any aftermarket tune to stock and retest if applicable
Replace the faulty module only after all circuit tests pass

Look up another code

Press / to jump to the box. Chevy-enhanced powertrain, body, chassis and network codes.

Sources and review

Review: no source links are recorded for this entry.

Last updated 2026-09-13.

Report a correction for P1779. Include your vehicle, the issue and a source if you have one.