P0577 Cruise control input circuit high

P0577 – OBD-II Trouble Code Technical Description

Cruise control input circuit high

What does the fault code mean P0577?

This P0577 diagnostic code applies to OBD-II vehicles with cruise control. The Engine Control Module (ECM) is responsible for the proper operation of the cruise control system and sets this code if problems occur with the cruise control system.

Possible reasons

The PCM and cruise control module work together to control vehicle speed. If the PCM detects a problem in this circuit, it runs a self-test on the cruise control system. Code P0577 is stored if the PCM detects abnormal voltage/resistance in the input circuit from the speed control. Most often, P0577 codes are associated with a malfunctioning cruise control switch. This defect may be caused by liquid spillage on the switches.

Causes of a P0577 code may include:

• Faulty cruise control function switch.
• Cruise control switch circuit open or shorted.
• Problems with the ECM (engine control module), such as an internal short circuit or open circuit.
• Damaged connectors in the cruise control system.
• Blown fuses, which may indicate more serious problems such as short circuits or power surges.

What are the symptoms of a fault code? P0577?

The most common symptom of a P0577 code is the cruise control system or its functions not working. Other possible symptoms may include the CEL (check engine light) coming on after a few driving cycles, caused by the ECM detecting a problem. You may also experience erratic or intermittent operation of the cruise control functions and the cruise control indicator light or stay off.

How to diagnose a fault code P0577?

To diagnose the P0577 code, it is important to:

1. Use an OBD-II scanner/code reader and a digital volt/ohm meter.
2. Inspect wiring and connectors, replace/repair damaged components.
3. Write down all codes and freeze frame data before clearing.
4. Clear the codes and check if they return. If yes, continue diagnostics.
5. Check the cruise control switch and compare it to factory specifications.
6. If the switch is faulty, replace it based on your vehicle's specifications.
7. After replacing the switch, clear the codes and test drive.
8. If the problem continues to recur, apply technical bulletins (TSBs) and perform additional diagnostics, possibly requiring specialized equipment.

Remember that the exact steps may vary depending on the make, model, and year of your vehicle, so it is important to follow the recommendations in the repair manual for your specific vehicle.

Diagnostic errors

Common errors when diagnosing a P0577 code include:

1. Inadvertent replacement of components: The mistake is that many car owners and repairmen can immediately replace the cruise control switch without conducting a deeper diagnosis. The switch can be an expensive component, and replacing it without being sure it's faulty may be unnecessary.
2. Need for additional diagnostics: Besides the switch, there may be other things that cause the P0577 code, such as problems with the wiring, connectors, ECM (engine control module), and even blown fuses. A more in-depth diagnosis is needed to accurately determine and eliminate the cause.
3. Insufficient circuit check: It is not always enough to simply inspect the wiring and connectors. Sometimes wiring problems can be invisible or only appear in certain conditions. Effective diagnostics include voltage, resistance, and continuity measurements.
4. Failure to update data after repair: Once components are replaced or repaired, active codes must be cleared and a test drive performed to ensure the problem no longer occurs. Failure to update the data may cause the P0577 code to reappear.
5. Ignoring technical bulletins: Some occurrences of the P0577 code may be related to known problems described in the manufacturer's technical bulletins. Ignoring these bulletins may result in missing important diagnostic and repair information.

To successfully diagnose and resolve the P0577 code, it is important to follow a systematic process, conduct a comprehensive inspection, and consult the manufacturer's technical documentation when necessary.

How serious is the fault code? P0577?

Code P0577 is a minor fault that does not affect engine performance but does cause the cruise control to not function. While this does not require immediate repair, it is important to understand that the vehicle may fail an emissions test if the code is not resolved, so it will need to be reset after repair. It is recommended that you resolve this issue to avoid potential more serious problems in the future.

What repair will help eliminate the code? P0577?

To resolve the P0577 code, the following steps are recommended:

1. Replace the cruise control switches if they are found to be faulty.
2. Inspect and repair any loose, disconnected, or corroded wires in the cruise control system.
3. After the repair is completed, you will need to clear the P0577 code using an OBD-II scanner/reader and test drive it to ensure that the cruise control is functioning correctly and the code is no longer activated.
4. If the P0577 code does not return after repair and the cruise control operates normally, the problem has been successfully resolved.
5. If the problem persists, further diagnostics will need to be carried out, perhaps using specialized equipment or by contacting a professional mechanic for a more in-depth analysis.

What is P0577 Engine Code [Quick Guide]

P0577 – Brand-specific information

• P0577 Mazda cruise control input circuit above minimum parameters
• P0577 Mercedes-Benz Cruise Control Input Circuit High