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OBD-II Trouble Code Technical Description
The Actuator Supply Voltage C Circuit/Open
What is the meaning of this?
This is a generic powertrain diagnostic trouble code (DTC) that typically applies to OBD-II vehicles. Vehicle makes may include but are not limited to Dodge, Chrysler, Ford, Chevrolet, Toyota, Honda, Nissan, etc.
The ECM (Engine control module) is responsible for monitoring and adjusting numerous sensors, solenoids, actuators, valves, etc., as well as ensuring that all of these components are operating seamlessly and in conjunction to meet desired values. This is done to ensure optimal economy and performance of your vehicle. In this case, if you receive a P2684 or a related code, depending on your make and model, you may experience transmission drivability issues.
It is important to note that in my experience with European models, I have also seen this code as an EVAP diagnostic code. With these potential differences in mind, it is necessary to refer to your service manual for proper diagnostic direction. In most cases, your symptoms will indicate the systems/components you need to work with to rectify the fault.
When it comes to the P2684 and related codes, the ECM has detected an abnormal value within the actuator supply voltage circuit. It identifies this abnormality by comparing the actual values to the desired ones. If they fall outside of the desired range, the MIL (Malfunction indicator lamp) on your instrument panel will illuminate. The ECM must monitor this fault through multiple drive cycles before illuminating the MIL. It is important to research the designation for “C” within the circuit, as it could indicate a certain wire, harness, location, etc., depending on your make and model. Always refer to OEM (Original equipment manufacturer) technical service information for this.
The TCM (Transmission control module) may also detect this depending on the specific description for this code in your make and model.
P2684 (Actuator Supply Voltage C Circuit/Open) is active when the ECM or TCM has detected an open (or general malfunction) within the actuator supply voltage “C” circuit.
What is the severity of this DTC?
The severity of this DTC is set to moderate. Given the fact that there are multiple code descriptions, caution should be exercised during diagnosis. Proper service data will be necessary. If this happens to be a transmission code in your case, it is advisable to repair it sooner rather than later. Using a vehicle with an active transmission code on a daily basis poses a risk that should be avoided.
What are some of the symptoms of the code?
Symptoms of a P2684 diagnostic code may include:
What are some of the common causes of the code?
Causes for this P2684 trouble code may include:
What are some P2684 diagnostic and troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins (TSB) for known issues with the specific vehicle.
Advanced diagnostic steps become very vehicle specific and may require the appropriate advanced equipment and knowledge to perform accurately. We include basic steps below but refer to a vehicle year/make/model/powertrain specific repair guide for specific steps for your vehicle.
Basic Step #1
The approach to diagnosing this will depend on your make and model and the symptoms you are experiencing. Generally, the first thing to do is clear the codes with your scanner and drive the vehicle until the code becomes active again. Once you have located the correct circuit/harness, inspect it for any damages. It is possible for the circuit to be routed under the vehicle where it can be damaged by road debris, dirt, ice, etc. If any open and/or chafed wires are present, repair them. It is also a good idea to inspect the connectors involved. Disconnect them to inspect the pins for any bent or damaged ones that could cause electrical issues. Sometimes, high resistance within a circuit can cause excessive heat, leading to insulation burn-through. This would indicate that you have found the problem.
NOTE: Always solder and shrink wrap any damaged wires, especially when they are exposed to the elements. Replace connectors with OEM ones to ensure proper electrical connections.
Basic Step #2
Locate your actuator using your service information. In some cases, these can be externally accessible. If this is the case for your vehicle, you can verify the integrity of the actuator itself. The desired values involved in this test vary significantly, so make sure to have your multimeter and service manual on hand. Always use appropriate test pin connectors to avoid unnecessary damage to the connections. If the recorded values are outside of the desired range, the sensor can be considered defective and should be replaced with a new one.
Basic Step #3
Inspect your ECM (engine control module) and TCM (transmission control module) for any obvious damage. Sometimes, they are located in a position where water can become trapped and cause corrosion. The presence of green powder should be taken as a warning sign. Given the complexities of ECM diagnosis, a licensed technician should take over from this point.
This article is strictly for informational purposes only, and the technical data and service bulletins for your specific vehicle should always take precedence.
Professional Service
While we always recommend seeking professional mechanical assistance to solve this issue, if for some reason that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to function. If you are interested in this option, please upload your ECU file to our portal.
