Cruise Control Vent Control Circuit Low
P0587 indicates the cruise control vent control circuit voltage is below the expected threshold. This circuit controls the vent solenoid that regulates vacuum to the cruise control servo, preventing it from maintaining set speed when activated.
What You Might Notice
- Cruise control will not engage or maintain set speed
- Check Engine Light illuminated on dashboard
- Cruise control button becomes unresponsive
- Inconsistent cruise control operation
- Vehicle speed fluctuates when cruise control is active
Most Common Causes
- 1
Faulty cruise control vent solenoid
The solenoid coil has failed or has excessive resistance, causing insufficient voltage to reach the circuit. This is the most common cause of P0587.
- 2
Damaged wiring or connectors
Corroded, broken, or loose wiring between the PCM and vent solenoid creates an open circuit or high resistance path, reducing voltage to the solenoid.
- 3
PCM output driver failure
The engine control module's output circuit for the vent solenoid has failed internally, unable to supply proper voltage to the circuit.
- 4
Blown fuse or relay
The dedicated fuse protecting the cruise control circuit is blown, or the relay controlling power to the vent solenoid has failed.
How to Diagnose It
- 1
Check Faulty cruise control vent solenoid — The solenoid coil has failed or has excessive resistance, causing insufficient voltage to reach the circuit. This is the most common cause of P0587.
- 2
Check Damaged wiring or connectors — Corroded, broken, or loose wiring between the PCM and vent solenoid creates an open circuit or high resistance path, reducing voltage to the solenoid.
- 3
Check PCM output driver failure — The engine control module's output circuit for the vent solenoid has failed internally, unable to supply proper voltage to the circuit.
- 4
Check Blown fuse or relay — The dedicated fuse protecting the cruise control circuit is blown, or the relay controlling power to the vent solenoid has failed.
How to Fix It
- 1
Test and replace vent solenoid
Use a multimeter to test solenoid resistance and voltage supply. If resistance is out of specification or no voltage reaches the solenoid, replace the cruise control vent solenoid assembly.
- 2
Inspect and repair wiring
Check the wiring harness and connectors between the PCM and vent solenoid for corrosion, damage, or loose connections. Repair or replace damaged sections and clean corroded connectors.
- 3
Check and replace fuse/relay
Locate the cruise control fuse and relay in the fuse box using the vehicle's service manual. Test continuity and replace if blown or faulty.
- 4
Test PCM output circuit
If wiring and components test good, the PCM output driver may be defective. Consult a professional diagnostic scan tool or take the vehicle to a specialist for PCM testing and reprogramming.
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