P0587
UniversalCruise Control Vent Control Circuit Low
The vehicle has detected a low electrical signal in the circuit that controls the cruise-control vent function. That function helps manage the cruise-control system; depending on the vehicle design, a fault may prevent cruise control from operating or affect how it responds. The code identifies a detected circuit condition, not a confirmed failed part.
⚠️ Before You Begin (Safety First)
Avoid using cruise control until the issue is diagnosed. If cruise control does not disengage using its normal controls, use the brakes and move to a safe place as soon as practical, then seek assistance.
Common Symptoms
- Cruise control may not engage because the system detects a fault in its vent-control circuit.
- Cruise control may switch off or fail to maintain the selected speed, depending on the vehicle's system design.
- The cruise-control warning indicator or a check-engine light may appear.
- There may be no noticeable symptoms if the vehicle disables cruise control without affecting normal driving.
Common Causes
- Damaged wiring or a short to ground may pull the circuit signal low.
- A loose, corroded, or damaged connector may interfere with the circuit.
- The vent-control device or its electrical coil, if fitted, may have an internal fault.
- A fault in the circuit's power supply, ground, or control-module output may cause the low reading.
Diagnostic Steps
- Do not use cruise control while the fault is present, especially if its normal disengagement behavior is uncertain.
- Check whether other cruise-control or electrical warning lights are present and note any related symptoms; this helps a technician assess the broader fault pattern.
- With the vehicle safely parked and switched off, visually inspect accessible cruise-control wiring and connectors for obvious damage, looseness, or corrosion. Do not disconnect or probe unfamiliar terminals.
- Check the owner's manual for safe, vehicle-specific guidance on inspecting relevant fuses; replace a fuse only with the specified type and rating, and do not repeatedly replace a fuse that fails.
- If the code returns or wiring checks reveal a problem, arrange diagnosis using vehicle-specific service information rather than replacing a part based on the code alone.
When to Call a Professional
A technician can check for related codes, review available cruise-control data, and test the vent-control circuit using the vehicle-specific wiring diagram. Testing may include checking wiring and connectors, the control device or actuator as equipped, and the module's circuit output. The exact procedure depends on the model, year, and engine.
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Commonly Asked Questions
Does P0587 prove that the cruise-control vent device needs replacement?
No. It reports a low condition in the vent-control circuit. Wiring, connectors, the circuit supply or ground, the control device, or the module's output may need to be checked before identifying a failed part.
Can I drive with P0587?
The vehicle may remain drivable, but cruise control may be unavailable or behave differently. Avoid using cruise control until the fault is diagnosed, and stop in a safe place if it does not disengage normally.
What does 'circuit low' mean here?
The control system detected an electrical signal below the expected range for the cruise-control vent-control circuit. The code alone does not identify the exact cause.
Could P0587 appear without an obvious change in driving?
Yes. Some vehicles disable cruise control while leaving ordinary driving unaffected, so the driver may notice only that cruise control is unavailable or a warning light is on.
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