Mazda (Ford) PWM idle valve circuit from original ECU

matt_fulghum · Post by **matt_fulghum** » Mon Jul 16, 2007 5:34 pm

I've traced the circuit for the pwm idle valve through my stock ECU, pretty much just for kicks, and I was wondering if anyone was interested in seeing the circuit diagram I made of it. Also, I'm not entiiiirely sure how it works, so if anyone could explain some of it to me, it'd be much appreciated.

I've found data sheets for the two transistors... the SC4065 is a transistor meant for driving DC motors (which the PWM idle valve is)

Jarmo · Post by **Jarmo** » Sun Jul 29, 2007 11:47 pm

You must have SC4065's base and emitter crossed at that schematic.
That c945 could be 2sc945.

matt_fulghum · Post by **matt_fulghum** » Mon Jul 30, 2007 1:39 am

I'm almost positive that the 4065's correct (I have the datasheet for it, and I double checked). It is definitely a strange circuit.

My dad thinks that it's some kind of differential amplifier setup, which it certainly looks like, although I don't know what D801 is in there for...

Jarmo · Post by **Jarmo** » Mon Jul 30, 2007 2:15 am

I won't argue with that but if you turn B and E around then it comes to basic switch, possibly with a current limiting function (R805). R806 and D801 are there for flyback.