Technical Description of OBD-II Trouble Code
The Cruise Control Input Circuit is registering a high voltage
What does that signify?
This is a standard diagnostic trouble code (DTC) for powertrain issues and is commonly found in OBD-II vehicles with cruise control. It can be applicable to various vehicle makes such as Chevrolet (Chevy), Toyota, Ford, Harley, Dodge, Ram, Ford, etc.
The ECM (Engine control module) is responsible for ensuring that the engine functions properly while maintaining acceptable levels of emissions, fuel economy, performance, and comfort features. Cruise control is a convenient feature for long trips as it allows the vehicle’s speed to be controlled automatically. However, if there are any defects in the cruise control system, the ECM may disable it. One indication of complete disablement is the absence of the cruise control light on the dashboard when attempting to activate it.
In general, this trouble code indicates an electrical malfunction in the control input, which can have multiple potential causes. The P0577 Cruise Control Input Circuit High and related codes (P0575 and P0576) are triggered when the ECM detects a high voltage condition in the cruise control input circuit.
Cruise control switches:
What is the severity of this DTC?
This particular code is considered a minor issue that does not require immediate repair. The engine performance will not be affected, allowing the vehicle to remain operational. The main problem associated with this code is the inability to use the cruise control function.
However, it is important to note that when the ECM displays a P0577 or any other P code, the vehicle may not pass an emissions test. Therefore, it is crucial to clear the code after every repair before undergoing a retest. Failure to do so may prevent the mechanic from accurately identifying the problem, potentially leading to more serious issues in the future.
What are some of the symptoms of the code?
The most common symptom of the P0577 code is the malfunction or complete failure of the cruise control system. Other possible symptoms include:
What are some of the common causes of the code?
Possible causes for the P0577 cruise control code include:
What are some diagnostic and troubleshooting steps for P0577?
The first step in troubleshooting any malfunction is to consult the Technical Service Bulletins (TSB) for known issues specific to the vehicle.
Advanced diagnostic steps will vary depending on the vehicle and may require specialized equipment and knowledge for accurate testing. The following are basic steps, but it is recommended to refer to a vehicle-specific repair guide for detailed instructions.
Basic Step #1
After using an OBD-II DTC scanner to retrieve the active P0577 code, thoroughly inspect the vehicle’s connectors, wiring, and other components of the cruise control system. Replace, reconnect, or repair any damaged connectors (e.g., broken tabs, heat damage, corrosion, etc.). Clear the code and perform a short test drive to check if the cruise control functions properly. If the repair is successful, ensure that the check engine light no longer reappears. If the light comes back on and the code is stored in the ECM again, continue with further diagnostics.
Basic Step #2
Test the cruise control switch (also known as the multifunction switch) according to the service manual specific to the make and model of the vehicle. This will involve using a DVOM (or multimeter) to measure the electrical values. Compare the actual values with the manufacturer’s desired values to determine if the switch is the problem or if it can be ruled out.
Basic Step #3
If the switch is found to be defective, replacing it may require removing steering column covers, especially if there are airbags in the way. Follow the specific steps for your vehicle to replace the switch. After replacing it, clear any active codes and test drive the vehicle.
This article is for informational purposes only, and it is always important to prioritize the technical data and service bulletins specific to your vehicle.
