P1561
Cruise Vent Solenoid.
- GM
- Powertrain
- Manufacturer code
- Low severity
How this code is built
- P
- SystemPowertrain
- 1
- Defined byThe manufacturer
- 5
- AreaVehicle speed, idle control and auxiliary inputs
- 61
- FaultThe specific fault in that area
What it means
On GM vehicles, P1561 relates to the cruise control vent solenoid circuit. The vent solenoid releases vacuum from the cruise servo so the throttle returns when cruise is cancelled or the brake is pressed. The control unit sets the code when the solenoid circuit's electrical state does not match the commanded state, or the circuit reads open or shorted. Exact circuit details and whether the fault is monitored vary by model and year.
Symptoms
- Cruise control will not engage or drops out unexpectedly
- Cruise control fails to cancel promptly when braking
- Cruise control warning or service light on, where fitted
- Engine management light on
- Cruise speed hunts or surges
Possible causes
- Faulty cruise vent solenoid or servo assemblylikely
- Damaged, chafed or corroded wiring to the vent solenoidlikely
- Poor connection or corrosion at the solenoid or control unit connectorpossible
- Vacuum leak or split hose at the cruise servo affecting the vent operationpossible
- Faulty brake switch or related cruise input causing inconsistent operationrare
- Fault within the control unit driver circuitrare
How to diagnose
- Read all stored codes and freeze frame data, and note whether other cruise or brake switch codes are present
- Check that the cruise control behaves as described, including cancelling when the brake pedal is pressed
- Visually inspect the solenoid, servo, vacuum hoses and wiring for damage, chafing, heat or water ingress
- Inspect the connectors at the solenoid and control unit for corrosion, bent pins or looseness
- Check the supply voltage and ground at the solenoid connector against the manufacturer wiring diagram
- Measure the solenoid coil resistance and compare with the model specification
- Command the solenoid with a suitable scan tool function, if supported, and confirm it operates and the circuit responds
- Check the vacuum supply and hoses to the servo for leaks, following the model-specific procedure
How to fix
- Replace the cruise vent solenoid or servo assembly if it is faulty or out of specification
- Repair or replace damaged wiring and ensure it is properly routed and secured
- Clean or replace corroded or damaged connectors and terminals
- Replace split or perished vacuum hoses and refit securely
- Replace a faulty brake switch if testing shows it is at fault
- Clear the code after repair and road test to confirm it does not return
Can I keep driving?
The car is generally safe to drive, but cruise control may be unavailable or not cancel as expected, so avoid using it until repaired. Book it in at your convenience, and stop using cruise at once if it fails to release when braking.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.