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P0574Cruise Control System - Vehicle Speed Too High

The cruise control system detected a vehicle speed signal above the maximum allowed for cruise operation.

Definition

The PCM compares vehicle speed against a calibrated ceiling while the cruise control system is active or armed, and sets P0574 when the reported speed exceeds that limit. In most cases the vehicle was not actually overspeeding — the code is triggered by an erratic or inflated speed signal from the VSS or wheel speed sensors, or by incorrect tire size or final-drive gearing skewing the speed calculation. Cruise control is disabled as a failsafe, the speedometer may act erratically, and on some vehicles transmission shift quality suffers because the same signal feeds shift scheduling. The MIL typically stays off, but the cruise indicator may flash.

Common causes

  • Faulty or erratic vehicle speed sensor (VSS) signal
  • Damaged VSS reluctor/tone ring or metal debris on the sensor tip
  • Tire size or axle ratio changed without recalibrating the PCM
  • Chafed or EMI-contaminated VSS wiring causing signal spikes
  • Actual sustained operation above the cruise speed ceiling (informational when genuine)
  • Faulty instrument cluster or ABS module retransmitting a bad speed value

Common misdiagnoses

  • Replacing the cruise control switch or servo when the speed signal is at fault
  • Replacing the brake light switch
  • Replacing the PCM before checking tire size and VSS signal quality
  • Replacing the transmission for shift complaints caused by the erratic speed input

Troubleshooting steps

  1. 1.Record vehicle speed data during a road test

    Graph the VSS PID with a scan tool and look for spikes or values far above true speed, especially over bumps or at steady cruise.

  2. 2.Compare speed sources

    Check PCM vehicle speed against wheel-speed PIDs and GPS; a single outlier isolates the faulty sensor or module.

  3. 3.Verify tire size and gearing

    Confirm installed tire diameter and axle ratio match the PCM calibration; reprogram the calibration if the vehicle was modified.

  4. 4.Inspect the VSS and tone ring

    Remove the sensor, check for metal debris on the magnetic tip, and inspect the reluctor for damaged or missing teeth.

  5. 5.Check VSS wiring routing and shielding

    Look for harness sections routed near ignition components or damaged shielding that lets noise ride on the speed signal.

  6. 6.Clear the code and confirm

    Road test at highway speed with cruise engaged and verify a stable speed reading and no code reset.

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