Fault code P0590 – cruise control multi-function input “B” circuit stuck

Fault code P0590 is called “Cruise Control Multi-Function Input “B” Circuit Stuck” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0590

This diagnostic trouble code (DTC) is a generic code. Error P0590 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly from model to model.

Fault code P0590 – cruise control multi-function input

Cruise control was designed for comfort, the sole purpose of which is to maintain the vehicle speed set manually by the driver. The driver does not need to control the accelerator pedal. If the car is equipped with an automatic transmission, he can control and adjust the shifts according to the driving conditions in real time.

This code refers to a specific input circuit in the cruise control system. Refer to your service manual to determine which wire or circuit to focus on. Since the “B” circuit may vary from manufacturer to manufacturer.

If there is a short in the multifunction input circuit “B” of the cruise control, the control module (PCM) will write code P0590 into memory and turn on the instrument panel warning light. As for the letter “B”, it may indicate a connector, a wire, or a group of circuits.

Symptoms of vehicle malfunctions

The main signal that an error P0590 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be written in the memory as a fault).
  2. Cruise control does not work completely.
  3. Unstable operation of the cruise control.
  4. Some functions do not work as they should (e.g. setting, resuming, accelerating, etc.).
  5. Cruise control is on, but not working.
  6. The cruise control light illuminates regardless of the switch position.

Code P0590 has a low severity because it does not affect safety or major vehicle components. But, like any electrical problem, it is better to fix it, so that the malfunction does not worsen in the future.

Factors that can cause this error code

The error code P0590 can mean that one or more of the following problems have occurred:

  • Cruise control switch is defective.
  • Wiring problem (breakage, chafing, etc.).
  • Faulty connector (e.g. corroded contacts).
  • Debris/dirt is mechanically interfering with the cruise control switch.
  • Sometimes the cause is a defective PCM module.

How to fix or reset OBD-2 code P0590

Some suggested steps for troubleshooting and fix the error code P0590:

  1. Usually you just need to repair or replace the damaged wires to fix this error.
  2. It is also necessary to check the connection connectors.
  3. Check for debris that is interfering with the cruise control switch.
  4. If no faults are found, the PCM module may be faulty.

Diagnose and repair of problems

The first step in the P0590 troubleshooting process is to review the Technical Service Bulletins (TSB). For known problems with a particular vehicle.

Next, locate the vehicle’s multi-function cruise control switch and visually inspect it for contamination. Plastic buttons get dirty very easily, causing them to not function properly.

Make sure that the mechanical operation of the switch is smooth and uninterrupted. Any problem should be corrected.

To access the connectors and harnesses of the cruise control switch input circuit, you may need to remove the protective plastic. After that, check the continuity of the wires and connections.

A problem with the PCM module is, in most cases, a last resort to diagnose error P0590. Given the fact that this can be one of the most expensive repairs, it’s best to leave it to the professionals.

On which vehicles does this problem occur most frequently

Fault code P0590 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Alfa Romeo
  • Chevrolet
  • Chrysler
  • Dodge
  • Ford
  • Jeep
  • Land Rover
  • Mazda
  • Nissan
  • Opel
  • Toyota

Fault code P0590 can sometimes be found with other errors. The most common are the following: P0589, P0591, P0592, P0593.


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