Storing the P2104 OBD2 diagnostic code indicates that the vehicle’s main computer has found a malfunction and limits the Throttle Actuator Control system. This situation is known as the fault test mode. In this mode, the engine will not accelerate until the malfunction is corrected.
When the fail-safe mode is activated, the Powertrain Control Module (PCM) forces the TAC (Throttle Actuator Control) system to remain inactive. The malfunction may be directly related to the TAC System or may be due to abnormal voltages in some vehicle systems. Other error codes may appear along with the P2104 code.