P1561
Cruise Vent Solenoid.
- Buick
- 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
P1561 on a Buick refers to the cruise vent solenoid circuit, part of the vacuum-operated cruise control system fitted to some older GM models. The control unit saw a fault in the vent solenoid circuit, such as an open circuit, short or a commanded state that did not match the feedback, and stored the code. The exact test criteria vary by model and year, so check the manufacturer's data for the vehicle.
Symptoms
- Cruise control does not engage or will not hold set speed
- Cruise control cuts out unexpectedly or surges
- Cruise control does not release properly when braking
- Malfunction indicator lamp or cruise warning lamp on in some cases
- Stored P1561 with no other noticeable change in driveability
Possible causes
- Faulty cruise vent solenoid or its vacuum valve assemblylikely
- Damaged, corroded or loose wiring or connector at the vent solenoidlikely
- Split, perished or disconnected vacuum hose to the cruise servopossible
- Faulty or misadjusted brake switch affecting cruise releasepossible
- Open or short circuit in the supply or control wire to the solenoid, including blown fusepossible
- Fault in the control unit driver circuitrare
How to diagnose
- Read the stored codes and freeze frame data, note any other cruise or brake switch codes, then clear and see if P1561 returns
- Check the relevant fuse for the cruise circuit
- Visually inspect the vent solenoid, its connector and wiring for chafing, corrosion, heat damage or water ingress
- Inspect the vacuum hoses and servo for splits, kinks or loose fittings, and check the servo holds vacuum
- Check the brake switch operation and adjustment, as it often controls the vent function
- Measure the solenoid resistance and compare with the manufacturer's specification for that model
- Check supply voltage and ground at the solenoid connector, then test the control wire for continuity and shorts to ground or supply
- Command the solenoid with a suitable scan tool function if available and confirm it operates
How to fix
- Replace the faulty cruise vent solenoid or valve assembly
- Repair or replace damaged wiring and clean or renew corroded connector terminals
- Replace perished or leaking vacuum hoses or a faulty cruise servo
- Replace or adjust the brake switch
- Replace the blown fuse after finding and fixing the cause of the overload
- Repair or replace the control unit only after all wiring and component tests have been passed
Can I keep driving?
Low severity
The car is normally safe to drive, but the cruise control may not work reliably. Book it in at your convenience, and avoid relying on cruise control until it is repaired.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.