Output shaft speed sensor (OSS) problems

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Nov 6, 2023 | 05:32 PM

RemingtonCG

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Output shaft speed sensor (OSS) problems

I have an 03 6.0 that I just replaced the trans in, new trans is out of an 03 as well. Long story short I got it all back together and it’s giving all the usual signs of the oss going out. It’s throwing the p0720 code. I replaced it and nothing changed. So I checked the resistance for all the wires that go to the sensor, when I checked them all individually, From sensor connector to the pcm connector (c1381b). I got zeros all across the board, but when I checked between the 12v (reference voltage) wire to the ground (signal return) wire I got 1970 on my meter. I’m not experienced with a multi meter or electrical problems. But dose that mean I have a short between those two wires. I did check between the 12v and ground wires whilst it was running and got 12v every. Any advice is appreciated.

Nov 6, 2023 | 05:38 PM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

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From: SE Florida

Was the harness disconnected on both ends when you checked the resistance?

Nov 6, 2023 | 05:48 PM

RemingtonCG

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Oss

Quote:

Originally Posted by Mark Kovalsky

Was the harness disconnected on both ends when you checked the resistance?

Yes, I was just sitting here wondering if that would make a difference

Nov 6, 2023 | 06:04 PM

RemingtonCG

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Oss

Quote:

Originally Posted by RemingtonCG

Yes, I was just sitting here wondering if that would make a difference

I checked from the pcm connector to the sensor connector when checking each wire individually, but when I checked the 12v and ground wire I checked them both from the sensor connector. The pcm end was unplugged while I was taking that measurement.

Nov 6, 2023 | 07:48 PM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,739

Likes: 2,669

From: SE Florida

Was it also disconnected at the sensor end?

Nov 6, 2023 | 09:24 PM

RemingtonCG

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Solution

Quote:

Originally Posted by Mark Kovalsky

Was it also disconnected at the sensor end?

Well I did some more poking around and checked the ohms on the OSS and I had a bad out of the box unit. Swapped it out and that problem if solved. New problem is the transmission is throwing an incorrect gear, ratio code. Which is causing it to go into fourth gear and cause my overdrive light to flash again. Is this something that if I just keep driving it gently it will relearn or is it going to be a deeper problem try than that?