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GTECH Calibration
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P1562

Cruise Vacuum Solenoid.

  • GMC
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
5
AreaVehicle speed, idle control and auxiliary inputs
62
FaultThe specific fault in that area

What it means

P1562 on a GMC relates to the cruise vacuum solenoid circuit. The control unit saw a fault in the circuit or operation of the solenoid that controls vacuum to the cruise control servo, such as an open circuit, short or abnormal electrical reading. The exact test conditions and whether the system is vacuum or electronically operated vary by model and year.

Symptoms

  • Cruise control will not engage or cancels unexpectedly
  • Cruise control surges or fails to hold set speed
  • Cruise control warning or service light on, where fitted
  • Engine warning light on
  • Cruise control works intermittently

Possible causes

  • Faulty cruise vacuum solenoid or vent/vacuum valvelikely
  • Damaged, chafed or corroded wiring to the solenoid (open circuit or short)likely
  • Poor connection or corroded terminals at the solenoid or control unit connectorlikely
  • Split, disconnected or leaking vacuum hose or cruise servopossible
  • Faulty brake switch or related cruise control input affecting the circuitpossible
  • Fault within the control unit driver circuitrare

How to diagnose

  1. Read all stored codes and freeze frame data, noting any other cruise, brake switch or voltage-related codes
  2. Check the cruise control fuse and battery and charging voltage
  3. Visually inspect the solenoid wiring, connectors and terminals for damage, heat, water ingress and corrosion
  4. Inspect the vacuum hoses and cruise servo for splits, loose fittings and leaks, following the model's vacuum routing
  5. Check the brake and clutch switch operation and adjustment, where fitted
  6. Measure solenoid coil resistance and compare with the manufacturer's specification for that model
  7. Check for power, earth and control signal at the solenoid connector using the wiring diagram
  8. Clear the code and road test to see whether it returns

How to fix

  • Replace the cruise vacuum solenoid if its resistance or operation is out of specification
  • Repair or replace damaged wiring and clean or renew corroded connector terminals
  • Replace split or leaking vacuum hoses or a faulty cruise servo
  • Replace or adjust a faulty brake or clutch switch
  • Repair or replace the control unit only after wiring and solenoid faults have been ruled out

Can I keep driving?

Low severity

The car is safe to drive as normal, but cruise control may not work. Book it in at your convenience.

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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