P0574 - Cruise control system - vehicle speed too high.

P0574 – OBD-II Trouble Code Technical Description

Vehicle speed is too high.

What does the fault code mean P0574?

The "P" in the first position of the Diagnostic Trouble Code (DTC) indicates the powertrain system (engine and transmission), the "0" in the second position indicates that it is a generic OBD-II (OBD2) DTC. The last two characters "74" are the DTC number. OBD2 diagnostic trouble code P0574 means that a problem has been detected with the cruise control system.

The cruise control system allows the vehicle to maintain a constant speed set by the driver without having to keep your foot on the accelerator pedal. If the PCM detects an anomaly in the operation of this system, such as the cruise control speed limit being exceeded, it stores a P0574 trouble code and activates the Check Engine Light.

Code P0574 indicates that the vehicle speed has exceeded the cruise control system operating limit. Other cruise control related trouble codes include P0575, P0576, P0577, P0578, P0579, P0584, P0558, P0586, P0587, P0588, P0589, P0590, P0591, P0592, P0593, P0594 and P0595.

Possible reasons

Although damaged connections and connectors can cause trouble code P0574, it can also be triggered by attempting to use cruise control at excessive speed. Blown fuses can also cause this code, but it may indicate more serious problems.

Other potential causes for a P0574 code to turn on include:

1. Faulty cruise control switch.
2. Wiring damage or short circuit in the wires associated with the switch.
3. An open circuit caused by a faulty electrical connection.

What are the symptoms of a fault code? P0574?

Symptoms of a P0574 trouble code include:

1. The check engine light or engine maintenance light comes on.
2. Inoperability of the cruise control system, resulting in the inability to set the vehicle speed using this system.

If the PCM stores code P0574, the check engine light will usually also turn on. In some cases, it may take several driving cycles before the Check Engine light comes on. However, in some specific vehicle models, this code may not activate the Check Engine Light at all.

How to diagnose a fault code P0574?

To properly diagnose the P0574 trouble code, your mechanic will need:

1. Advanced scanner and digital volt/ohm meter for measuring voltage and testing circuits.
2. Inspect all cables, connectors and components for damage.
3. Download all freeze frame data and stored codes for analysis, especially if the code runs intermittently.
4. Clear DTC P0574 and retest the system.
5. If the code returns, suspect a faulty cruise control switch.
6. It is possible to jack up the vehicle and, with the help of an assistant, reach a speed of 25 to 35 mph before engaging the cruise control to check the continuity of the circuits while it is operating.
7. Disconnect the electrical connector from the cruise control switch, check the voltage and compare the results to the manufacturer's specifications.
8. If there is no voltage or ground signal at the cruise control switch, a mechanic should check the continuity between the interior switches, the fuse panel, and the PCM, comparing the results to the manufacturer's specifications.
9. Check the cruise control ON/OFF switch voltage using a digital voltmeter.
10. Clear the P0574 trouble code and recheck the system to see if it returns.

Diagnostic errors

A mechanic may make the following mistakes when diagnosing the P0574 trouble code:

1. Skipping Visual Inspection: Failure to sufficiently inspect all cables, connectors and components for damage may result in missing important physical problems such as broken wires or damaged connections.
2. Incorrect removal and reset of the fault code: If a mechanic clears the P0574 code but does not find and fix the root of the problem, the error may recur and the vehicle will remain faulty.
3. Failure to follow the field test procedure: Failure to test the cruise control system on the road at the required speed may result in missed interruptions or instability in operation.
4. Incorrect cause identification: A malfunctioning cruise control switch is often the cause of a P0574 code, but a mechanic may miss this important aspect and focus on other parts of the system.
5. Incorrect comparison of results to production specifications: Failure to follow the exact parameters and specifications set by the manufacturer when comparing measurement results may lead to incorrect conclusions.
6. Failure to follow the sequence of actions: Improperly performing diagnostic steps, such as disconnecting the PCM, can make it difficult or slow to get to the root of the problem.
7. Failure to check cruise control switch voltage: Insufficiently checking the voltage at the cruise control switch may cause you to miss potential problems with this component.
8. Incorrect handling of freeze frame data and stored codes: Not taking into account freeze frame data and stored codes may prevent you from identifying intermittent problems that do not always show up at the time of diagnosis.
9. Failure to check electrical connections in interior and fuse panel: Damaged wires or connections in the passenger compartment may be the cause of the P0574 code and may be missed.
10. Insufficiently checked circuits between interior switches, fuse panel and PCM: This check may be omitted, which may result in undiagnosed problems in the system.
11. Failure to follow-up check after DTC is cleared: If a mechanic does not check the system after resetting the code, he may not notice whether the error has returned or not.

How serious is the fault code? P0574?

The main problem that occurs when trouble code P0574 appears is the inability to correctly set the cruise control system. If cruise control is important to the car owner, then it is recommended to solve this problem by first eliminating the code and restoring the functionality of the cruise control system.

At this time, this problem is not considered serious. Carly recommends periodically checking her condition to see if the situation worsens in the future.

*Please note that each vehicle is unique. Carly functionality varies by vehicle model, year, hardware, and software. To determine the available features on your vehicle, connect the scanner to the OBD2 port, connect to the Carly app, perform the first diagnostic and evaluate the available options. Please also remember that the information provided is for informational purposes only and should be used at your own risk. Mycarly.com is not responsible for any errors or omissions or for the results arising from the use of this information.

What repair will help eliminate the code? P0574?

A mechanic can resolve the P0574 trouble code by performing the following repairs:

1. Replace any damaged wires, connectors, or components that may be corroded, shorted, or otherwise damaged.
2. If the test reveals that one of the cruise control switches is faulty, replace it.
3. If blown fuses are found, replace them. In this case, it is also necessary to identify and eliminate the cause of the blown fuse before continuing work.
4. If the cruise control ON/OFF switch is faulty, it is recommended to replace it.

What is P0574 Engine Code [Quick Guide]

P0574 – Brand-specific information

P0574 MERCEDES-BENZ DESCRIPTION

Engine control module ( ECM) controls the cruise control system. ECM Sets an OBDII code when the cruise control system is not to factory specifications.