Was doing a small service on my son's EF gas.I was interested in how the BBM worked,I read in the workshop manual, 12volts is applied to a solenoid at a certain rpm which allows vacuum to open the vacuum motor.At idle there should not be any voltage.But I noticed on my son's car, that when he starts the motor the vacuum motor has full vacuum and I tested the switch and it has 12v.Now, is there a fault with the PCM (what's a PCM) or is it supposed to do this because it has gas.I did not think to try it on petrol to see???

Vaccum is applied to the actuator from 0 to 3800rpm. This keeps the BBM locked in long runner mode.

At 3800rpm, the solenoid vents the vaccum, which releases the actuator and opens the short runners in the BBM.

From memory, 12v is constantly applied to the solenoid, it is the ground that is switched from the ECU.

So what is happening is correct. Sounds like the book is giving the wrong impression.

Yep, stupid workshop manual.I should have checked my BF.It opens up when its been started.Thanks