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Home / DTC / P1566 — Cruise Control System Engine RPM Too High

P1566 — Cruise Control System Engine RPM Too High

Detailed page for trouble code P1566.

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Code

P1566

CHRYSLER P — Powertrain

Cruise Control System Engine RPM Too High

Brand: CHRYSLER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Stuck or binding throttle body/throttle plate
  • Faulty electronic throttle control (ETC) actuator or motor
  • Accelerator pedal position sensor fault or correlation error
  • Vacuum leak or intake air leak causing high idle/RPM
  • Incorrect idle air control (IAC) or throttle actuator control (TAC) operation
  • Cruise control servo or actuator malfunction (mechanical or electrical)

Symptoms

  • Cruise control unable to maintain set speed or overshoots speed
  • Engine RPM higher than set/expected during cruise control operation
  • Cruise disengages unexpectedly or sets to incorrect speeds
  • Check Engine Light (MIL) illuminated and code P1566 stored
  • Erratic or unresponsive throttle behavior while cruise is active

What to check

  • Use a scan tool to read DTCs, freeze frame, and live data PIDs (engine RPM, commanded engine RPM/throttle, vehicle speed, cruise active status)
  • Verify whether code is current, pending, or historical; note operating conditions in freeze frame
  • Compare accelerator pedal position (APP) sensor and throttle position (TP) sensor PIDs for correlation while key on/engine off and during driving
  • Monitor ETC/throttle actuator duty cycle and position while engaging cruise control
  • Inspect throttle body for carbon buildup, sticking plate, or binding linkage/cables (if mechanical)
  • Inspect vacuum lines and intake boots for leaks, splits, or disconnections

Signal parameters

  • Engine RPM (actual) — compare to commanded/target RPM
  • Commanded engine torque or commanded throttle position
  • Accelerator pedal position (APP) sensor values and APP 1 vs APP 2 correlation
  • Throttle position (TP) or throttle plate angle PID
  • ETC/throttle actuator duty cycle and actual position feedback
  • Vehicle speed sensor (VSS) — cruise set vs actual speed

Diagnostic algorithm

  1. Read and record all stored codes and freeze frame data using an OEM-capable scan tool
  2. Attempt to reproduce the fault under controlled conditions (safe road or lift) with cruise control engaged; monitor live PIDs listed above
  3. If APP/TP correlation is incorrect, test pedal position sensors and throttle position sensors per service manual; replace sensors if out of spec
  4. Inspect and clean throttle body; verify throttle plate moves freely and returns to closed position; inspect throttle shaft for wear
  5. Check for intake vacuum leaks (visual inspection, smoke test) and repair as needed
  6. Verify brake/clutch switches and related wiring; ensure cruise disable circuits are functioning
  7. Perform wiggle tests on wiring harnesses and connectors to ETC, APP, TP, cruise actuator, and PCM while monitoring live data for intermittent faults
  8. If ETC motor or actuator shows abnormal behavior, follow manufacturer's actuator test procedures; replace if confirmed faulty
  9. Check transmission gear and torque converter operation if RPM anomaly relates to driveline load; inspect related transmission codes
  10. If wiring and components check out, verify PCM software level and apply updates or reflash per TSBs
  11. Clear codes after repairs and perform a road test with cruise engaged to confirm the fault does not return

Likely causes

  • Electronic throttle actuator (ETC) sticking or controlling improperly
  • Accelerator pedal position sensor out of correlation with throttle position sensor
  • Vacuum or intake leak raising engine speed when cruise is engaged
  • Faulty cruise control actuator not communicating proper set speed status

Fault status

⚠️ Status
P1566 — Cruise Control System Engine RPM Too High: PCM detected engine speed higher than target while cruise control active. Freeze frame and live data available for diagnosis.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.0 hours

Similar codes

P1565 P0506 P0121 P2110 P2135
193

Browse 193 CHRYSLER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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