P0590 OBD-II Trouble Code: Cruise Control Multi-Function Input “B” Circuit Stuck
P0590 code definition
The P0590 trouble code notes an electrical issue with the cruise control multi-function input “B” circuit.
What the P0590 code means
The P0590 code is a generic OBD-II trouble code that detects a problem with the cruise control multi-function input in the “B” area of the circuit. The “B” refers to a general area of the circuit, rather than any specific component. The cruise control module works in tandem with the powertrain control module (PCM) to help control and regulate the vehicle’s speed automatically when the cruise control system is engaged. If the PCM notes that the speed of the vehicle cannot be contained, then the entire cruise control system will be tested. If voltage/resistance levels are noted by the PCM to be outside of their standard range, then the P0590 code will be triggered.
What causes the P0590 code?
The P0590 trouble code is usually the result of a malfunctioning cruise control switch. The cruise control switch can malfunction due to the circuity failing, which can happen when liquids are spilled on the cruise control buttons. The P0590 code can also be the result of defective electrical components, such as damaged or loose wires, or corroded and damaged connectors.
What are the symptoms of the P0590 code?
The P0590 code is usually accompanied by the check engine soon Warning Light illuminating on the dashboard, though this isn’t the case in all vehicles. When the code is detected, the cruise control system will most likely not work. It is also common for blown fuses to occur.
How does a mechanic diagnose the P0590 code?
The P0590 code will be diagnosed using a standard OBD-II trouble code scanner. A trained technician will use the scanner to look at the freeze frame data and assess the P0590 code. The technician will also look for additional trouble codes that may be present. The codes should then be reset, and the vehicle restarted. If the code does not return upon restart, then it was likely triggered incorrectly, or is an erroneous error.
If the P0590 code persists, then the mechanic should visually inspect all of the electrical components in the cruise control circuit. Any blown fuses, short wires, or loose connectors should be replaced, as should any damaged components. It’s important for technicians to be extremely thorough when searching for blown fuses.
Next, the cruise control switch should be checked. The mechanic can either inspect the switch manually, or reset the PCM and try the cruise control system again. If the problem persists, it should be assumed that the cruise control switch is the issue.
Following any replacements, the mechanic should reset the trouble codes and restart the vehicle to see if the P0590 code remains. That way the mechanic can tell as soon as the code has been eliminated and the issue is resolved.
Common mistakes when diagnosing the P0590 code
The most common mistake that is made when diagnosing the P0590 code comes from failing to properly follow the OBD-II trouble code protocol. The protocol should always be adhered to, step by step, to make sure that all repairs are efficient, and don’t feature erroneous replacements. It is common for entire components to be unnecessarily replaced when blown fuses are the actual issue.
How serious is the P0590 code?
The P0590 trouble code won’t keep a vehicle from being drivable. However, the trouble code will likely keep the cruise control system from functioning, so it should be repaired as soon as possible.
What repairs can fix the P0590 code?
The most common repairs for the P0590 trouble code are:
- Replacement of the cruise control switch
- Replacement of the wires in the system
- Replacement of the connectors in the system
- Replacement of the fuses in the system
Additional comments for consideration regarding the P0590 code
In some vehicles, the cruise control multi-function input “B” circuit issue will have to occur three separate times before the P0590 code is triggered.
Need help with a P0590 code?
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