P0721 popping up but somethings odd

[diesel_s]

So I took my truck into the dealer because I just cant pass emissions, the first time i have ever pulled up royally failed emissions, it hurt my soul. So after checking the codes myself, I kept getting the drive cycle error code P1000, i had P0455 and fixed that 3 days ago myself, had a catalyst code, and fixed that one myself too. Now i have Po721.....720 popped up as well but they told me its being caused by the P0721 code. So i know i need a flush but what kills me is that none of this started until i got my last flush, ridiculous. Lately my truck had been good after much work performed by myself and a few buddies. Yesterday, my transmission was shifting horribly, out of no where, spikes in RPM, sticking from gear to gear and sometimes it seemed to drop out of gear. None of that has ever happened before. So i took it to the dealer today and after running test on it, they narrowed it down to the oss sensor which they say is inside the transmission and i was quote $670 alone in labor to look at it and that i would be looking at over $1200 to do the job fully. I am a college student, work for my paps family business and freelance out of my buddies shop, Dynamic Sound. I do not have $1200 laying around, wont have that. Has anyone ever done this before? I have tools of all sorts and specialties and I am very handy around a car, i can breakdown an engine no problem but i have never had a thing for transmissions, they scare me. haha. Just wondering if anyone has ever replaced that sensor? The thing that confirms to me that it is the sensor is that after they cleared the code and reset the PCM, the truck drove home smoothly. No spike in RPM, no sticking or slipping, no dropping out of gear, nothing. It even accelerated better. Any ideas?

 

[PopRichie77]

The OSS, sensor, output shaft speed, is on the outside of the trans near the top rear.
The internal sensor is (TSS) turbine shaft speed.

 

[diesel_s]

Thank you for the correction, but I'm just looking for advice

 

[albi1cnobi1]

I think what PopRichie77 was trying to say is if they did tell you it was the OSS (output speed sensor) then you can replace that yourself. The TSS (turbine shaft sensor), if that's what they told you, is inside and requires going into the trannie to replace it.

 

[PopRichie77]

P0721 is the OSS sensor, it is on the outside of the trans, easy to replace, so why not replace it?

 

[drdoom]

EDIT: The OSS (Output Shaft Speed) sensor is the one at the rear of the transmission.

 

[diesel_s]

I see now, but from what they said I believe it's the TSS but I read that for most people it was a simple wire, and that's how it seems for mr because once the codes were erased, the truck drove perfectly fine

 

[diesel_s]

Where is the TSS sensor in the tranny? I'm gonna drop the tranny in the morning, because for the price the dealer wants to change the sensor, I can either it myself or buy a new tranny and have money left over

 

[diesel_s]

So i reviewed the information again and apparently the mechanic told the service writer that the TSS was causing the issue but the code they kept getting was the P0721 which as u guys stated was the code for the OSS, and as soon as they cleared the codes, truck drove like a dream unttil i put 150 miles on it when it began to try to diagnose its "drive cycles" where it then began to act funny again...so at this point, i do know its a sensor if it works fine before the drive cycle diagnostic tries to kick in

 

[PopRichie77]

You said the code was P0741, that is the OSS sensor.
Code P0715 is the TSS sensor.
You need to find out what the code was for sure.

sorry made error it was 721

 

[diesel_s]

I'm getting two codes from it now and those are P0720 and 721

 

[drdoom]

I'm getting two codes from it now and those are P0720 and 721

Those are the Output Speed Sensor.

 

[diesel_s]

Yeah, it's the easy one to change so I'm going to get one now then do a flush

 

[diesel_s]

I went to buy the sensor today and none of the local stores had it so i get it tomorrow morning along with an exhaust gasket I've been needing. Going tonremove the old one in the morning and check the wiring to it to make sure all is well. Sensor only cost $19 to purchase out here.

 

[drdoom]

Where is the TSS sensor in the tranny? I'm gonna drop the tranny in the morning, because for the price the dealer wants to change the sensor, I can either it myself or buy a new tranny and have money left over

Here is a photo of the center support, with the TSS (Turbine Shaft Speed) sensor visible at the five O-clock position.

It is about half-way down into the guts, behind the pump and the front brake & coast clutch drum.

 

[drdoom]

And a little more info I took from the manual:

P0721, OSS, Output Shaft Speed sensor signal "noisy"
(PCM has detected an erratic OSS signal)
Harsh shifts, abnormal shift schedule, no torque converter clutch engagement

P0715, TSS, Insufficient input from Turbine Shaft Speed sensor
(PCM detected a loss of TSS signal during operation)
Increased engine RPM on engagement, harsh shifts, delayed shifts with hard apply (slip/bump feel)

 

[diesel_s]

So I get started today in order to change the OSS and I don't know why this never crossed my mind, but I never checked the dipstick. Because of where the sensor sits, I realize that I can't access it as easy as it thought so I begin to remove the necessary pieces to allow the tranny to hang lower so I can get to the OSS. As soon as I pull out the drive shaft, I get soaked in fluid, so I push it back in and check the fluid level and it is far above where it should be. It is actually sitting on the elbow of the dipstick that is way above the full level. So I call a few shops and a few other dealers and they all unanimously told mr to take it back to the dealer that did the flush and make them fix it correctly, especially since none of this started until they flushed it