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GTECH Calibration
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P1586

Cruise Control Brake Switch 2 Circuit.

  • Saturn
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
5
AreaVehicle speed, idle control and auxiliary inputs
86
FaultThe specific fault in that area

What it means

P1586 on a Saturn means the control unit has found a fault in the second cruise control brake switch circuit. The brake switch signals are compared, and the module saw a reading that is missing, stuck or does not agree with the other brake switch input or the brake lamp state. Exact switch arrangement and strategy can vary by model and year.

Symptoms

  • Cruise control will not engage or cancels unexpectedly
  • Cruise control works intermittently
  • Brake lamps stay on, or do not light when braking
  • Malfunction indicator lamp or a service warning on the dash
  • Cruise control set speed drops out when touching the brake pedal lightly

Possible causes

  • Brake switch out of adjustment or worn, giving a stuck or inconsistent signallikely
  • Faulty brake switch (internal contact failure)likely
  • Damaged wiring, chafed loom or poor connector contact in the switch circuitpossible
  • Corroded or loose terminals at the switch connector or at a related connectorpossible
  • Blown brake lamp fuse or faulty brake lamp circuit affecting the shared signalpossible
  • Brake pedal bracket or pedal stop worn, so the switch plunger does not travel correctlypossible
  • Fault in the control unit that reads the switchrare

How to diagnose

  1. Read all stored codes and freeze frame data, and note whether other brake or cruise codes are present
  2. Check the brake lamps work correctly and turn off fully when the pedal is released
  3. Check the relevant fuses, as the circuit layout depends on the model
  4. Inspect the brake switch, its mounting and the pedal plunger for wear, damage or misadjustment
  5. Inspect the switch wiring and connector for chafing, corrosion, bent pins and poor terminal tension
  6. Watch the brake switch inputs on a scan tool while pressing and releasing the pedal, and check both inputs change state cleanly and agree
  7. Test the switch circuit for continuity, shorts and voltage drop against the wiring diagram for that model
  8. Clear the code and road test to confirm it does not return

How to fix

  • Adjust or refit the brake switch to the correct position
  • Replace a faulty brake switch
  • Repair damaged wiring or replace the affected section of loom
  • Clean or replace corroded or loose connector terminals
  • Replace a blown fuse after finding why it failed, and repair any brake lamp circuit fault
  • Repair or replace a worn pedal bracket or stop

Can I keep driving?

Medium severity

The car is usually safe to drive as the brakes themselves are not affected, but cruise control may not work. If the brake lamps are not working properly, fix that first, as it is a safety and legal issue.

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

This code for other makes

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