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DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P0590

P0590Cruise Control Multi-Function Input 'B' Circuit Stuck

This code indicates that the cruise control multi-function input 'B' circuit has been detected as stuck by the cruise control module or powertrain control module (PCM). The computer monitors the voltage or signal from the cruise control switch circuit and has determined that the signal remains in a fixed state longer than expected, which prevents normal cruise control operation.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • The cruise control system does not engage or function at all
  • The cruise control indicator light may flash or stay illuminated
  • The horn, turn signals, or other steering wheel-mounted controls may stop working if they share the same circuit
  • The engine may exhibit no drivability issues, and the only sign is the warning light
  • Often no symptoms besides the warning light, especially if the fault is intermittent

Common causes, most likely first

  1. Faulty cruise control multi-function switch (often integrated into the steering wheel or stalk)
  2. Damaged or worn clock spring (spiral cable) in the steering column
  3. Corroded, loose, or damaged wiring and connectors in the cruise control circuit
  4. Stuck or shorted button contacts inside the multi-function switch
  5. Failed cruise control module or PCM (less common)
  6. Aftermarket accessories or improper previous repairs interfering with the circuit

How to diagnose and fix it

  1. Use a scan tool to read live data from the cruise control switch inputs and verify that input 'B' is stuck
  2. Inspect the cruise control switch and wiring for physical damage, corrosion, or contamination
  3. Test the multi-function switch with a multimeter to check for continuity and resistance in each button position
  4. Check the clock spring for continuity and signs of wear, especially if other steering wheel controls are affected
  5. Inspect all connectors and harnesses between the switch, clock spring, and control module for loose pins or chafed wires
  6. If the switch and wiring test good, substitute a known-good cruise control module or PCM to rule out internal failure
  7. Clear the code and test-drive the vehicle to confirm the repair and ensure the code does not return

Common misdiagnosis of a stuck cruise switch

  • A stuck cruise control button can be caused by spilled sticky liquids or debris in the switch assembly, which is often overlooked during diagnosis.
  • The clock spring is a frequent failure point on high-mileage vehicles and can cause this code even when the switch itself tests fine.
  • This code can be set by a momentary short to voltage or ground in the wiring, so intermittent faults may not appear during a simple resistance test.
  • Some vehicles use a single wire with different resistor values for each cruise function, so a stuck input can be caused by a faulty resistor inside the switch rather than a mechanical stuck button.
  • After replacing the switch or clock spring, the cruise control system may require a relearn or calibration procedure with a scan tool to function correctly.

Can I keep driving with P0590?

The vehicle remains safe to drive because cruise control is a convenience feature and this fault does not affect engine, braking, or steering operation. Avoid using the cruise control until the fault is repaired, and be aware that other steering wheel controls may also be affected if the clock spring is failing.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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