so i took my truck in to have the headgaskets replaced. truck ran fine other than oil leaking down the side of the block and it had gotten worse over the past year.

when i picked it up, the overdrive "off" light is blinking and it shifts really hard. i had the code ran and it was the output speed sensor.

Where is this sensor located?

i removed the one for the speedometer, but it doesn't look like the one that I got from the autoparts.

The one they gave me looks the same as the one I put on the top of the rear end.

I plan on changing the speedometer one as well since it is only $18.

 

The OSS is on the drivers side, midway up the transmission and in front of the extension housing.

Darrin

 

how far forward is it from where the drive shaft yoke slides into the transfer case?

 

On a 2wd truck, it's about 13 inches forward from the base of the seal that the yoke slides into.

Darrin

 

mine's a 4wd truck. so that doesn't help me find the oss. does anyone else know for sure?

off memory, the speedometer speed sensor with the little gear is about 8"-1 foot from where the yoke slides in.

 

Ah, the fact that it's a 4wd is handy to know when trying to help

I am also assuming something else here since you didnt' specify, and that is that we are talking about a 4R70W transmission.

On that transmission it's really simple to find. On the drivers side of the transmission it's the only small sensor that is in the body of the transmission itself. There are no sensors on the passenger side by the way.

As an FYI, I happend to have a really handy situation here. The kids are on fall break right now and one of them likes to come to the shop with me whenever she can. So, just to test to see if the info I am giving is sufficient, I told our 13 y/o daughter that same exact thing and also told her that the drivers side of the transmission was the left side from where she was standing. She was able to point right to it on a transmission sitting here in the shop.

Trust me, it's super easy to find if she can do it. LOL

Take care.

Darrin

 

speedometer

http://shop.advanceautoparts.com/web...S_521808185___

abs

http://shop.advanceautoparts.com/web...S_521692923___

 

i changed the abs and found the speedo one last night. i will look for the oss tonight.

 

OSS sensor

http://shop.advanceautoparts.com/web...S_521821698___

well of course they gave me the wrong oss. this is the one that is in the transmission. however, it was tought to get to with the front wheel drive shaft in the road. i got it out, and the one wire was pulled out of the connector. i'm assuming this must have happened when the engine was pulled to do the headgaskets. i fixed this and the transmission seems to be working normal now and no flashing overdrive off light so far.

thanks

 

Dude, you will not believe how often I get into pissing matches with customers over stuff like this. They tell me "My transmission wont shift. All I have is second gear and reverse". Instead what I hear is "My wiring somehow got messed up during installation". Then, invariably, they tell me that it can't be on their end because their old transmission shifted and the BS begins.

You don't know how happy it makes me to see someone like you who took the initiative to figure out the problem and fix it. I don't see how so many can have such a hard time with simple diagnostics like that. In the end it was actually pretty simple wasn't it?

Blows me away...

Congrats on having the wherewithall to figure it out and fix it on your own.

Darrin

I think I am going to keep a link to this thread handy. I think it might be useful. LOL

 

yea, like i said, when i took the truck for the headgaskets it was running shifting fine.

i didn't want to go back to the guy who did the headgaskets if i could avoid it because he did me a favor even doing the headgaskets since he is so busy doing easier types of work (only charged me $500 for labor for the job and that included getting out the rusted exhaust manifold studs when he put the new exhaust manifolds on.

i think what must have happened is when he was disconnecting wires or didn't prop up the tranny good when he removed the engine to pull one wire completely out. it seemed like that particular wire didn't have much slack in it.

i was kind of thinking all along it was a bad ground or a ground wire didn't get hooked back up.

best part is, i only changed the sensor in the rear end, even though i didn't need to evidently, and it only cost $13.

i really wish i understood electronics/testing resistances/ etc. in trouble shooting but no matter how hard i try, i am baffled. unless someone shows me a picture of exactly what to do and what setting to have the meter on, i'm clueless. haha.

 

And see how easy it was for you? With that, do you see how it's so easy for me to get quite frustrated with 'professional shops' who are supposed to know how to diagnose and troubleshoot?

Like I said, it just blows me away sometimes. It also says a lot about the 'industry' in general that it happens so often. F'n amazing really...

We need more people out there doing this stuff who are willing to do the simple stuff to run the problem down. Usually it really is just that easy.

On top of all that though, you did it when it really wasn't your job. Trust me, that says a lot.

Darrin

 

yea, i do 99% of my own work on vehicles. thanks to these car forums i've been able to solve / diagnose a lot of problems. i don't trust most garages to do work, especially the chains.

there are two reasonable priced garages near me though that i'll get things done at once in awhile if its a tough job or i'm in a hurry.

my dad ended up putting $2200 in a tranny/torque convertor rebuild from amoco in his ranger. only for it to go out again in a year, but the mileage was over the warranty. they charged another $700 in it for them to fix it again. it took him almost 2 months to get it back the second time also.

The head gasket job on this truck i didn't want to tackle though. too many other projects/home improvement projects going on. the guy even said the hatching was still in the cylinders at 170k.

doing head gaskets/engines/etc. on smaller trucks or cars isn't bad (4 cylinders), but i don't have a garage and good place to work, and i didn't want to have the truck down for an extended period of time, in case i need to haul or tow something. bad time of year in pennsylvania with the shorter days and cold weather setting in.