P0574 code definition
A P0574 trouble code signifies that the Powertrain Control Module (PCM) has detected that the vehicle is traveling in excess of the maximum allowable speed for the cruise control system. Other related cruise control trouble codes include a P0575, P0576, P0577, P0578, P0579, P0580, P0581, P0582, P0583, P0584, P0585, P0586, P0587, P0588, P0589, P0590, P0591, P0592, P0593, P0594, and P0595 code.
What the P0574 code means
When driving using the cruise control, the PCM works in tandem with the cruise control module to assure that the vehicle travels at the speed set. If the PCM detects an abnormality, such as the vehicle exceeding the speed limit allowed by the cruise control system, then it runs a self test of the entire cruise control system in order to try and find the source of the problem. In addition, the PCM stores a P0574 trouble code and the Check Engine light illuminates.
What causes the P0574 code?
While shorted, open, corroded, or otherwise damaged wiring and connectors are some of the causes of the storage of a P0574 trouble code, attempting to set the cruise control while driving at excessive speeds can also cause storage of this code. Blown fuses can also cause a P0574 trouble code, though this is also an indicator of a much more severe problem.
What are the symptoms of the P0574 code?
Symptoms of a P0574 trouble code include the inability to set the vehicle speed via the vehicle's cruise control. If a P0574 trouble code is stored by the PCM, the Check Engine light is also usually illuminated. In some cases, such as with certain models of vehicles, multiple drive cycles are required before the Check Engine light illuminates. But, in some specific models, the Check Engine light is not illuminated at all for such codes.
How does a mechanic diagnose the P0574 code?
To properly diagnose a P0574 trouble code, a mechanic needs an advanced scanner and a digital volt/ohm meter. The mechanic also needs to perform the following steps:
- Inspect all wiring, connectors, and components for damage.
- Download all of the freeze frame data and stored codes in case the code is intermittent.
- Clear the P0574 trouble code and retest the system.
- If the code returns, suspect a faulty cruise control switch.
- The mechanic can also raise the vehicle and, with the aid of an assistant, allow the speedometer to reach 25 to 35 MPH before setting the cruise control. This allows the mechanic to test the continuity of the cruise control circuits while the vehicle and cruise control system are in operation.
- The mechanic should disconnect the electrical connector from the cruise control switch, testing for voltage with the digital volt/ohm meter, and compare their findings to the manufacturer's specifications.
- If the mechanic can detect no voltage or ground signal at the cruise control switch, they should then disconnect the PCM from the cruise control module and check the continuity of the circuits between the switches in the passenger compartment, the fuse panel, and the PCM. They should compare their findings with the manufacturer's specifications.
- Test the voltage of the cruise control ON/OFF switch with the digital volt/ohm meter.
- Clear the P0574 trouble code and retest the system to see if it returns.
Common mistakes when diagnosing the P0574 code
A common mistake among mechanics diagnosing a P0574 trouble code is to overlook a blown fuse, replacing components unnecessarily. As a result, the problem is not fixed and the P0574 trouble code returns.
How serious is the P0574 code?
The biggest issue arising out of the storage of the P0574 trouble code is that the cruise control refuses to be set. If cruise control use is important to a vehicle owner, then they need to get the problem fixed in order to clear the code and resume normal use of the cruise control system.
What repairs can fix the P0574 code?
A mechanic can fix a P0574 trouble code by performing the following repairs:
Replace the cruise control switches if testing determines any are faulty.
Replace any blown fuses. The mechanic should also determine the cause of the blown fuse and make the appropriate repairs before proceeding further.
Replace the cruise control ON/OFF switch if faulty.
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