Throttle Actuator Control Module Performance
P2108 indicates the PCM has detected a performance problem with the Throttle Actuator Control module and has entered failsafe mode to protect the engine. This restricts throttle operation, causing the engine to run at idle speed only or potentially preventing it from starting altogether.
What You Might Notice
- Engine will not start or has difficulty starting
- Little to no throttle response when accelerating
- Poor engine performance that may worsen over time
- Check Engine Light illuminated
- Smoke or unusual emissions from tailpipe
- Increased fuel consumption
Most Common Causes
- 1
Throttle body malfunction
The electronic throttle body itself may be failing, stuck, or not responding properly to PCM commands. This is the most common cause of TAC module performance codes.
- 2
Wiring or connector issues
Damaged, corroded, or loose wiring and connectors between the PCM and throttle actuator can cause communication loss or intermittent electrical faults.
- 3
PCM software or calibration problem
The powertrain control module may need a software update, flash reprogramming, or may have internal calibration errors affecting throttle control.
- 4
Throttle position or accelerator pedal sensor failure
A faulty throttle position sensor (TPS) or electronic accelerator pedal sensor can provide incorrect signals, causing the PCM to restrict throttle operation.
How to Diagnose It
- 1
Check Throttle body malfunction — The electronic throttle body itself may be failing, stuck, or not responding properly to PCM commands. This is the most common cause of TAC module performance codes.
- 2
Check Wiring or connector issues — Damaged, corroded, or loose wiring and connectors between the PCM and throttle actuator can cause communication loss or intermittent electrical faults.
- 3
Check PCM software or calibration problem — The powertrain control module may need a software update, flash reprogramming, or may have internal calibration errors affecting throttle control.
- 4
Check Throttle position or accelerator pedal sensor failure — A faulty throttle position sensor (TPS) or electronic accelerator pedal sensor can provide incorrect signals, causing the PCM to restrict throttle operation.
How to Fix It
- 1
Scan and diagnose with professional equipment
Use a diagnostic scanner to read all stored and pending codes, check live data streams from the throttle actuator and sensors, and identify the specific failure point within the TAC system.
- 2
Inspect and clean or replace throttle body
Remove and inspect the electronic throttle body for carbon buildup, damage, or mechanical failure. Clean thoroughly or replace if defective. Verify smooth operation after service.
- 3
Check and repair wiring and connectors
Inspect all wiring harnesses and connectors between the PCM and throttle actuator for corrosion, damage, or loose connections. Repair, clean, or replace as needed.
- 4
Update PCM software or replace module
Flash the PCM with the latest manufacturer software update to correct calibration issues. If the module is faulty, it may require replacement and reprogramming.
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