Failing throttle actuator control (TAC) module; Corroded or loose electrical connectors at the TAC module or throttle body; Damaged or chafed wiring in the TAC module harness; Poor ground connection for the TAC module or throttle body; Internal fault in the electronic throttle body (throttle position sensor or actuator motor); Low or unstable battery voltage affecting TAC module operation; Water intrusion into the TAC module or its connectors

DTC codes / GM codes / P1517

P1517 · GMThrottle Actuator Control (TAC) Module Performance

Q: What does code P1517 mean?

Throttle Actuator Control (TAC) Module Performance. P1517 on a GM vehicle means the throttle actuator control (TAC) module has reported an internal performance fault to the engine control module (ECM). The ECM has detected that the TAC module's own self-checks or its commanded versus actual throttle position response have fallen outside the expected range, so it sets this code and typically commands reduced engine power.

P1517 on a GM vehicle means the throttle actuator control (TAC) module has reported an internal performance fault to the engine control module (ECM). The ECM has detected that the TAC module's own self-checks or its commanded versus actual throttle position response have fallen outside the expected range, so it sets this code and typically commands reduced engine power.

SystemPowertrain

Code typeGM specific

SeverityHigh

Fix difficultyProfessional

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Reduced engine power message or limp-home mode with limited throttle response
The engine may idle at an elevated or erratic speed
Cruise control may be disabled or stop working
The throttle may feel unresponsive or delayed when pressing the accelerator
Often no symptoms besides the warning light if the fault is intermittent
The engine may stall or refuse to rev past a limited RPM

Common causes, most likely first

Failing throttle actuator control (TAC) module
Corroded or loose electrical connectors at the TAC module or throttle body
Damaged or chafed wiring in the TAC module harness
Poor ground connection for the TAC module or throttle body
Internal fault in the electronic throttle body (throttle position sensor or actuator motor)
Low or unstable battery voltage affecting TAC module operation
Water intrusion into the TAC module or its connectors

How to diagnose and fix it

Scan all modules for stored and pending codes, and record freeze-frame data for P1517
Inspect the TAC module and throttle body connectors for corrosion, loose pins, or water intrusion
Check battery voltage and charging system output, and load-test the battery if it is more than three years old
Perform a voltage drop test on the TAC module ground circuit and repair any excessive resistance
Wiggle-test the TAC module harness while watching live throttle position and TAC data on a scan tool
Follow the GM diagnostic flow chart for P1517, which includes checking TAC module internal self-test results and commanded versus actual throttle position
Replace the TAC module only after wiring, grounds, and throttle body have been ruled out, then perform the required throttle relearn procedure

Why the TAC module gets blamed too often

A weak or failing battery is a common hidden cause of P1517 on GM trucks and SUVs, because the TAC module performs voltage-sensitive self-checks at key-on and can log this code before the engine even starts.
Corroded ground studs behind the left kick panel or on the engine block are frequently overlooked and can mimic a failed TAC module, so always perform a loaded voltage drop test before condemning the module.
P1517 can be set by a throttle body that is mechanically sticking or carbon-fouled, even though the code points at the TAC module, so inspect and clean the throttle bore before replacing electronics.
Intermittent P1517 that appears only in damp weather often traces to water intrusion at the TAC module connector or a chafed harness near the cowl, not to an internal module failure.
Replacing the TAC module without performing the GM throttle relearn and idle learn procedure will often leave the vehicle in reduced power mode and set the code again immediately.

Can I keep driving with P1517?

Do not continue driving with P1517 active because the vehicle is likely in reduced power mode with severely limited throttle response, which is unsafe in traffic. If the light is on but the vehicle drives normally, keep speeds low and avoid heavy acceleration until the fault is diagnosed.

Tools that help

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Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.