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DTC codes / Chrysler codes / P1558

P1558 · ChryslerCruise Control Servo Indicates Low

P1558 on a Chrysler vehicle means the powertrain control module (PCM) has detected that the cruise control servo signal circuit is reporting a low voltage condition when the system is commanded on. The PCM expects a specific voltage range from the servo's feedback or position sensor, and a reading below the acceptable threshold triggers this code.

SystemPowertrain
Code typeChrysler specific
SeverityLow
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • Cruise control fails to engage or drops out intermittently
  • Cruise control indicator light may flash or stay off when the button is pressed
  • No other drivability symptoms; the vehicle otherwise drives normally
  • Often no symptoms besides the warning light on the dashboard
  • Speed control may work only at certain speeds or after repeated attempts
  • Possible related codes for servo circuit or speed sensor stored in memory

Common causes, most likely first

  1. Faulty cruise control servo assembly (internal position sensor or motor failure)
  2. Damaged or corroded wiring harness at the servo connector
  3. Open or shorted servo signal circuit to ground
  4. Poor ground connection at the servo mounting point or chassis
  5. Defective cruise control switch on the steering wheel or stalk
  6. PCM internal fault on the cruise control input circuit (rare)

How to diagnose and fix it

  1. Inspect the servo connector and wiring for corrosion, chafing, or loose pins
  2. Check the servo ground circuit for continuity to chassis ground
  3. Measure the servo signal voltage with a multimeter while commanding cruise control on with a scan tool
  4. Test the cruise control switch operation using scan tool data to confirm it is not the source
  5. Substitute a known-good servo or perform a bench test of the servo motor and sensor
  6. Repair or replace damaged wiring as needed, then clear codes and verify cruise control operation
  7. If all external circuits test good, replace the cruise control servo and retest

Servo signal low does not always mean servo failure

  • A common misdiagnosis is replacing the servo when the real problem is a corroded ground wire at the servo mounting bolt, which skews the signal voltage low.
  • The cruise control switch on the steering wheel can develop high resistance that mimics a low servo signal, so always check switch data before condemning the servo.
  • On some Chrysler models, the servo signal circuit shares a splice with other sensors, and a short in an unrelated component can pull the voltage down.
  • The PCM may set P1558 only after the cruise control is commanded on, so a static voltage check with the system off can miss the fault.
  • Aftermarket cruise control systems or poor previous repairs are frequent culprits on older Chrysler vehicles, so inspect for non-factory wiring splices.

Can I keep driving with P1558?

The vehicle remains safe to drive because the cruise control system is disabled, but you should avoid using cruise control until the fault is repaired. No other safety systems are affected, so normal driving can continue.

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 Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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