My question is simple :
If we want to identify if our sensor is pull up or pull down design we check the signal wire wile sensor is disconnected and if we have some power there is a pull down and if not is potentially a pull up. So my question is this is: It is possible to find a pull up design that will have a bias voltage on the signal wire, and could potentially throw you off making you think that is a pull down design?
Never thought of this scenario :huh: I personally have never seen such a thing, but I guess it's possible. Is there a specific situation you're thinking of, or this just a theoretical question?
Well the question comes just on theory. See the thing is I had a little of hard time on a Volkswagen Jetta that I was working on a purge solenoid circuit code, and it was a ground side switch solenoid, and it had about 9 bias voltage on the ground, and to make it even more confusing the power wont come on, unless the car was running. so it trough me off a little bit and this potential variable came to my mind
Eagletech wrote: My question is simple :
If we want to identify if our sensor is pull up or pull down design we check the signal wire wile sensor is disconnected and if we have some power there is a pull down and if not is potentially a pull up. So my question is this is: It is possible to find a pull up design that will have a bias voltage on the signal wire, and could potentially throw you off making you think that is a pull down design?
I have never seen a bias on the signal wire or circuit of a hall effect or any other switch input type signal. Great question though.
Here is a video I did on this subject
Tanks for the replay I did saw the video and i read your book , but what about the case on witch you use the bias voltage to troubleshoot an magneto resistance sensor (ABS), is an switch input after all Thanks
Eagletech wrote: Tanks for the replay I did saw the video and i read your book , but what about the case on witch you use the bias voltage to troubleshoot an magneto resistance sensor (ABS), is an switch input after all Thanks
What about the magneto sensor? I'm not sure what your question is?
These are not switch inputs like the other ones we deal with. The computer is actually monitoring current flow and as I've shown in the 2 or 3 videos I've done on them, they are not all the same.
Topic Author
