P0588 - Cruise Control Vacuum Vent Control Circuit Low
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0588 is a generic OBD-II diagnostic trouble code indicating that the Engine Control Module (ECM/PCM) has detected an abnormally low voltage signal in the Cruise Control Vacuum Vent Control circuit. In vacuum-actuated cruise control systems, this valve is responsible for releasing vacuum to disengage the throttle actuator. A 'low' circuit condition typically points to a short to ground or an open circuit in the wiring or the solenoid coil itself, causing the voltage to stay below the calibrated threshold (usually <0.5V when high state is commanded). This is a safety-critical monitor ensuring the system can reliably disengage.
Possible Causes
Faulty vacuum vent solenoid (internal short in the coil)
Damaged wiring harness with a short to ground on the signal wire
Corrosion in the connector causing high resistance or open circuit
Faulty Engine Control Module (ECM) failing to drive the output circuit
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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