Technical Description of OBD-II Trouble Code
Malfunction in the Performance of Throttle Actuator Control Module
What does that signify?
This generic powertrain diagnostic trouble code (DTC) is applicable to all OBD-II equipped vehicles that utilize a drive-by-wire throttle control system, including but not limited to vehicles from VW, Chevy, Ford, Mazda, Volvo, Dodge, Audi, Alfa-Romeo, Cadillac, Toyota, etc.
The P2108 OBD-II trouble code is one of several codes that indicate a malfunction in the operation of the Throttle Actuator Control System, as detected by the Powertrain Control Module (PCM).
There are six codes associated with Throttle Actuator Control System malfunctions, namely P2107, P2108, P2111, P2112, P2118, and P2119. Code P2108 is triggered by the PCM when there is a malfunction in the performance of the Throttle Actuator Control System Module Processor.
The PCM manages the Throttle Actuator Control System by monitoring one or more throttle position sensors. The position of the throttle plate, controlled by one or more Throttle Actuator Control Motors, determines the operation of the throttle body. The PCM also monitors the accelerator pedal position sensor to gauge the driver’s desired speed and adjusts the throttle response accordingly. This is achieved by altering the current flow to the Throttle Actuator Control Motor, which moves the throttle plate to the desired position. Certain malfunctions may cause the PCM to restrict the operation of the Throttle Actuator Control System, resulting in fail-safe or limp mode, where the engine is either held at idle or may not start at all.
Code Severity & Symptoms
The severity of this code can range from moderate to severe, depending on the specific malfunction. Symptoms of a P2108 trouble code may include:
Common Causes Of A P2108 Code
Possible causes of this code may include:
Common Repairs
Diagnostic and Repair Procedures
Check for TSBs
The first step in troubleshooting any malfunction is to research the Technical Service Bulletins (TSBs) specific to the vehicle’s year, model, and power plant. This can save a significant amount of time by providing guidance in the right direction.
The second step is to locate all the components associated with the Throttle Actuator Control System, including the throttle body, throttle position sensor, throttle actuator control motor, PCM, and accelerator position sensor in a simplex system. A thorough visual inspection should be conducted to check the associated wiring for any obvious defects such as scraping, rubbing, bare wires, burn spots, or melted plastic. The connectors to each component should also be checked for security, corrosion, and damaged pins.
The last visual and physical inspection involves the throttle plate. With the ignition switch off, the throttle plate should be able to rotate by pushing on it, reaching the wide open position. If there is sludge behind the plate, it should be cleaned while accessible.
Advanced Steps
The advanced steps are highly vehicle-specific and require specialized equipment for accurate execution. These procedures involve using a digital multimeter and referencing the specific technical information for the vehicle. The voltage requirements vary depending on the vehicle’s specific year, model, and engine.
Circuit Checks
With the ignition switch in the off position, disconnect the electrical connector at the throttle body. Locate the 2 pins that connect to the motor or motors on the throttle body. Using a digital ohmmeter set to ohms, measure the resistance of the motor or motors. The motor should read approximately between 2 and 25 ohms, depending on the specific vehicle (refer to the manufacturer’s specifications for your vehicle). If the resistance is too high or too low, the throttle body will need to be replaced. If all tests have passed so far, the voltage signals to the motor should be checked.
If this process reveals the absence of a power source or ground, continuity testing may be required to assess the integrity of the wiring. Continuity tests should always be performed with the power removed from the circuit, and the normal readings should be 0 ohms of resistance unless otherwise specified by the technical data. Resistance or lack of continuity indicates faulty wiring that must be repaired or replaced.
We hope that the information in this article has provided helpful guidance in addressing the issue with your Throttle Actuator Control System. However, please note that this article is purely informational, and the specific technical data and service bulletins for your vehicle should always take precedence.
