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4r100 falling out of gear
First post here, been on other diesel sites trying to get some info as well.
Well this is what my truck does. OD light will flash when you pull up to a redlight and it feels like the trans looses what gear its in. Once it starts to roll it goes into first and shifts through all the gears fine. This is with the selector in drive. You can put the selecter in first and the trans goes into first and stays there. Well i ran a code scan and got a p0720 code. I know its for the OSS so i replaced that sensor and still getting the same code. So I next i pulled the whole wire harness for the trans looking for breaks or bad wires and ohmed and visually checked and couldn't find any bad wires.
Next i hook my scantool to it and go drive it, in data stream mode the transmission selector switch matches the shifter. As far as in park it says park, drive, it says drive. There is a listing called transmission gear and it says my truck is in 2nd when it should be in 1st. My transmission mechanically feel good. no slipping and shifts 1-2 2-3 3-4 and locks converter in 3 all like it should. When i watch it on the scan tool it says my trans is saying it shifts 2-3 3-4 4-invalid. I don't know understand could make the pcm read this and why i am still getting the p0720 code. Also when the od light is flashing and you shift the truck from drive in park, it will rev up a couple hundred rpms and then back down. Any info would be greatly appreciated.
My trans shifts solid firm and doesn't slip so i'm not convinced yet that its a mechanical problem with the transmission.