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P2100 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit Open (TACM)

Check Engine Light

P2100 code definition

Throttle Actuator Control Motor Circuit Open (TACM)

What the P2100 code means

P2100 is an OBD-II generic code which indicates that the throttle actuator control motor (TACM) circuit is open, as detected by the Engine Control Module (ECM). The throttle actuator will not work.

What causes the P2100 code?

  • The ECM does not get a correct closed throttle reading from the TACM during startup or during operation

  • The ECM puts the TACM in failure mode and closes the throttle valve if it is possible

What are the symptoms of the P2100 code?

  • The Check Engine Light will not be illuminated and the code will be set in ECM memory as a TACM fault.

  • The throttle will stay at idle and will not go above idle if the accelerator pedal is pushed.

How does a mechanic diagnose the P2100 code?

  • Scans and documents the codes in the ECM

  • Diagnoses as per the manufacturer's pinpoint test (prevents bodily damage from throttle plates closing on one’s fingers)

  • Clears the ECM code P2100 and verifies whether the code comes back

  • Monitors the throttle position sensors 1 and 2 when the accelerator is pushed to see if the TACM moves within specifications and both sensors are within specs

  • Tests and confirms the wiring and connector to the TACM to be good

Common mistakes when diagnosing the P2100 code

  • Clearing ECM memory codes before checking the freeze frame data of the failure
  • Failing to clear ECM codes after the P2100 codes are fixed
  • Moving the throttle plates by hand (causes other codes to appear in memory)

How serious is the P2100 code?

Code P2100 is an indication that the throttle cannot be opened by the actuator and the vehicle will only idle. This would make the vehicle not drivable.

What repairs can fix the P2100 code?

  • Replacing the throttle actuator assembly
  • Repairing the wiring or connection to the actuator assembly

Additional comments for consideration regarding the P2100 code

Code P2100 is the most common failure with the throttle actuator besides the actuators internal throttle plate position sensor. The actuator is replaced as an assembly. Trying to move the throttle plates by hand can cause the throttle plate to snap closed causing your fingers to get hurt.

Need help with a P2100 code?

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