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GTECH Calibration
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P1563

Cruise Vehicle Speed Set Speed Difference Too High.

  • Oldsmobile
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
5
AreaVehicle speed, idle control and auxiliary inputs
63
FaultThe specific fault in that area

What it means

P1563 on an Oldsmobile means the cruise control system has seen too large a difference between the actual vehicle speed and the speed the driver set. The control unit compares road speed with the set speed and logs the fault when the gap stays beyond its limit, so the system cannot hold the set speed properly. Exact set-and-fail conditions vary by model and year, so check the factory information for the specific car.

Symptoms

  • Cruise control will not hold the set speed
  • Cruise control cancels itself or will not engage
  • Vehicle speed surges or drifts above or below the set speed
  • Cruise indicator flashing or cruise control inoperative
  • Check engine light or service warning on
  • Erratic or incorrect speedometer reading

Possible causes

  • Faulty or erratic vehicle speed sensor signal or its wiringlikely
  • Throttle actuator or cruise control cable or servo sticking or not responding correctlylikely
  • Vacuum leak or faulty vacuum supply to a vacuum-operated cruise servopossible
  • Poor connections, corrosion or damaged wiring in the cruise control circuitpossible
  • Faulty brake or clutch switch giving wrong cancel signalspossible
  • Engine or transmission problem preventing the car from reaching or holding the set speed, such as a misfire or slipping gearboxpossible
  • Fault within the control module or an outdated calibrationrare

How to diagnose

  1. Read all stored codes and freeze frame data to see the road speed and set speed when the fault was logged, and check for other speed, throttle or engine codes
  2. Compare the speedometer reading with a known accurate speed to check the speed signal
  3. Visually inspect wiring, connectors and earths for the speed sensor and cruise control components for damage, corrosion or looseness
  4. Check the brake and clutch switch operation and their signals on live data
  5. Inspect the throttle cable, linkage or actuator for sticking, slack or damage, depending on how the model controls cruise
  6. Where a vacuum servo is fitted, check hoses and the servo for leaks and test the vacuum supply
  7. Road test with live data to watch actual speed against set speed and see when the gap develops
  8. Check the factory information for any updated calibration or known faults for the specific model and engine

How to fix

  • Repair or replace a faulty vehicle speed sensor or repair its wiring
  • Repair damaged wiring, connectors or earth connections
  • Replace faulty brake or clutch switches
  • Free off, adjust or replace a sticking throttle cable, linkage or cruise actuator
  • Repair vacuum leaks or replace the vacuum servo and hoses
  • Repair any underlying engine or transmission fault, and update the control module calibration only if an outdated one is confirmed as the cause

Can I keep driving?

Low severity

The car is normally safe to drive without cruise control, but expect the feature to be unavailable. Book it in soon, and avoid using cruise control until it has been checked if the speed is surging.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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