P0585
UniversalCruise Control Multi-Function Input A / B Correlation
The cruise-control system monitors two related input signals and detects that they do not agree as expected. These inputs help the vehicle interpret cruise-control commands. The system may disable cruise control or respond inconsistently; the code does not by itself identify a failed part.
⚠️ Before You Begin (Safety First)
If cruise control behaves unexpectedly or will not disengage normally, do not use it. If it cannot be disengaged safely, brake as needed and pull over to a safe place. Avoid testing cruise control in traffic.
Common Symptoms
- There may be no noticeable symptoms if cruise control is not being used.
- Cruise control may be unavailable if the system disables it after detecting mismatched inputs.
- Cruise-control buttons or commands may respond inconsistently if the input signals are not being interpreted as expected.
- A warning light or message may appear, depending on the vehicle.
Common Causes
- A cruise-control input switch or control may produce inconsistent signals.
- A loose, damaged, or corroded connector or wire may interfere with one or both input signals.
- A short or open circuit in the relevant wiring may cause the inputs to disagree.
- A control-module or signal-processing problem is possible, but should be considered only after the inputs and circuits are checked.
Diagnostic Steps
- Check whether cruise control is operating normally; do not test it in traffic, and stop using it if its response is unpredictable.
- Note any related warning messages and other diagnostic codes, since they may help identify a shared circuit or system issue.
- With the vehicle safely parked and switched off, visually inspect accessible cruise-control buttons and wiring for obvious damage or loose connections. Do not remove trim or probe wiring unless you have the correct service information.
- If the code returns or the inputs behave inconsistently, have both signals and their circuits tested using vehicle-specific procedures before replacing parts.
When to Call a Professional
A technician can check related fault codes, compare both input signals in scan data, and test the relevant circuits and connections using model-specific service information. Confirm the cause before replacing a switch or other component.
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Commonly Asked Questions
Does P0585 prove that the cruise-control switch is faulty?
No. It reports a mismatch between related cruise-control inputs. The switch, wiring, connectors, or control electronics may need checking before a cause is confirmed.
Can I keep driving with this code?
If the vehicle drives normally and cruise control is not used, the code may not affect ordinary driving. Do not use cruise control if it responds unpredictably or will not disengage normally.
Why might cruise control stop working even if the buttons look fine?
The system monitors electrical input signals, not just button appearance. A connection or wiring problem can make the signals disagree even when the controls look undamaged.
How is the cause distinguished from a faulty switch?
A technician can compare the two input signals in scan data and test the related wiring and connections using procedures for the specific vehicle.
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