12v hall effect power feed

2007 Lincoln MKX 3.5l AWD.
Long story short, there's no out put from the turbine speed sensor or output shaft senor.
Both are internal to trans and share a 12v power feed. There's no power from the PCM with the trans harness connected, and 12v disconnected.
Should the 12v feed to the 2 Hall effect sensors be able to carry any current? I want to load test the power feed to see if I'm dealing with a voltage drop from inside the PCM or if one of the sensors is shorted and pulling the voltage to ground.
Thanks!
Noah.

I'm not sure to be honest. Never current clamped a sensor as such. Will the 12v supply support your test lamp?


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Thanks for the reply Matt!
All I had was a scan tool and my old Vantage. I'm guessing it wouldn't have lit a test light even if everything was fine.
I wanted to put a bulb in the circuit, but decided not to. Mainly because even if the bulb didn't light, it wouldn't have been any proof either way. After all, it is just an input sensor power feed.

After watching the class room lectures on hall effect testing again last night, I'm going to treat this as if it were a 5v circuit. It has to be a shorted sensor in the trans. There's no short to ground on the feed or either signal wire.
If it's not a junk sensor, then something is pinched in the trans. Either way, I'm confident enough to drain the trans and pull the cover now.

That's if I can work on it today....

Classic example of needing a loadpro!! Haha

In all seriousness, can you see the two speed signals in live data? Can you tell if they're high or low side switched? If they're high, would jumping from the 12v feed and tapping quickly on the signal not confirm the pcm supply?
I think I'd better refresh on my basics. I feel I'm missing something obvious trying to reply to you.


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lol @ loadpro

That sounds exactly like the test i didn't think to do that would have proved the source and the signal circuit integrity.
Thanks Matt, I always forget I can do that

I think I was meant to say low side. We know what I meant.


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Subscribing to this thread for later.

I really don't know if that kind of 12V feed should support current or not. I remember reading GM flow charts for some of their Hall effect sensors, and they DO suggest using a test light to check the 12V feed (from the PCM) and ground. But, who knows if this Lincoln plays by the same rules. :silly: