Electrical Experts step in...

ravege

Active Member
Joined
Jul 10, 2008
The Park/Neutral switch: it takes a voltage, probably 12v, from the ECM (pin B10) to the P/N switch (orange/black wire). When the transmission is in Park or Neutral, it connects the B10 line to ground (black/white wire) and the ECM sees the circuit closed (and applies IAC, which isn't important for this thread).
Presumably, this only happens when the car is on. I want to use the P/N switch, but I need it to work in a car-off condition as well. In other words, car on or off, keys in or out, I want to be able to determine if the transmission is in P/N.
In a car off condition, I would need to splice in a 12v source to the B10 line - I think that's pretty straightforward. But when the car is on, wouldn't that spliced in 12v keep the circuit closed, thereby fooling the computer to think the transmission was *always* in P/N? Obviously not a desirable condition. Can someone think of an elegant solution to this? I'm clearly not an electrician, don't be too hard on me :notworthy: Or maybe there is an alternative to using the B10 line? The functionality will be tripping a relay that I only want active in P/N.
 
So, the Park neutral switch actually doesn't have 12v on it. It's a switch to ground. So, technically it will work all the time. Whatever you're adding to the circuit will be able to sense park or neutral regardless of the power on/off state of the car.
 
Thank you for your reply! But to sense that ground connection, a voltage has to be applied to see that the circuit is closed? I'm attaching an admittedly bad picture of the Buick wiring schematic and it shows a 12v within the ECM going out B10.
345413
 
Top