FixItFor.Us
P codepowertrainLow severity

P0586Cruise Control Vent Control Circuit/Open

An open or general fault has been detected in the circuit that drives the cruise control vent solenoid, the valve that releases servo vacuum to reduce or cancel throttle pull, so cruise control is disabled.

Definition

Vacuum cruise servos use a vent (release) solenoid that bleeds vacuum off the servo diaphragm to reduce throttle opening and to disengage smoothly; the module modulates it against the apply solenoid to hold speed. The module monitors the vent solenoid driver circuit and sets P0586 when it sees an open circuit or feedback that does not match the command. Because the module cannot guarantee controlled vacuum release with this circuit faulted, it disables cruise entirely, and the mechanical brake-pedal dump valve remains the safety backstop. The symptom is cruise that will not engage; there is no effect on normal driving and the MIL typically stays off.

Common causes

  • Open winding in the vent solenoid inside the servo assembly
  • Broken or chafed wire in the servo harness on the vent control circuit
  • Corroded or backed-out terminal at the servo connector
  • Open power feed shared by the servo solenoids
  • Failed vent solenoid driver in the cruise or engine control module

Common misdiagnoses

  • Vacuum hoses and check valve replaced for what is an electrical circuit fault
  • Brake switch replaced because cruise will not stay engaged
  • Servo replaced when a single harness wire is open
  • Cruise switch pod replaced for an actuator-side code

Troubleshooting steps

  1. 1.Inspect the servo connector and harness

    Check the vent solenoid terminal for corrosion or a backed-out pin and follow the harness for breaks near engine movement points.

  2. 2.Measure vent solenoid resistance

    Measure across the vent solenoid terminals at the servo; OL confirms an open winding, and typical spec is in the 20-60 ohm range (confirm in service data).

  3. 3.Confirm the power feed

    With the key on and cruise master switch on, verify battery voltage on the servo feed; the apply and vent solenoids usually share the same feed.

  4. 4.Check continuity to the module

    With both ends disconnected, verify the vent control wire has end-to-end continuity and no short to adjacent circuits.

  5. 5.Actuate the vent solenoid

    Use a scan tool output test or a fused jumper to energize the solenoid and confirm it clicks and releases vacuum from the servo.

Related codes