i got a hold of one with 104,000 mile on it for 175$ another 100$ for a warranty
is it worth it? my car has 119,00 miles on it...

if it is ok to get the trans what should be replace before installing?


and again before i do all this work people say i need my transmission rebuilt because of the input speed senor is gone is that something i can replace on my own or? that all i see wrong with the transmission i dont think the gears are bad...

Is it the right trans?

ya i called the guy on the phone to day the guy that had the transmission with 29k for the 2001 el do and he has this one in stock...

Didn't the Eldo come in two flavors, 275 HP (3.11 final drive) and 300 HP (3.71 final drive)?

yup... i was looking at the trans for with 29k out of a 2001 but it wont work.. but he has one that will work in stock with 104k... so is it a good buy? or

hell yeah. I paid $400 for one near me. It was only a 60K mile tranny, but it didnt' have a warranty.

alrite so i guess 104,000 mile transmission isnt all that bad then?

I've been trying to follow but I'm hopelessly lost. What is wrong with your present transmission?

the input speed sensor

So... why not just put in a new speed sensor?
The 4T80E is shit over about 80K, speed sensor is gonna run about $20 or less... Those are a PITA to do tranny swaps on! but the sensor replacement books for like 11 hours so i guess if you can find a LOW mileage trans than i say go for it... Personaly i would not buy anything with more than like 50K or so unless it comes with a decent warranty. This last month alone i have probably done 3-4 cadillacs all with less than 100K miles on them. Personaly my '99 ETC has about 110K and it seems to be OK so far but it was driven by an older man who put about 80K on it in the 8 years he owned it.


just my opinion (lead tech at AAMCO for the recrord)

Personaly i would offer this guy $450 shipped for the trans and he would probably take it.
http://cgi.ebay.com/ebaymotors/01-2001-Eldorado-AT-4T80E-Trans-Transmission-4-6L-29k_W0QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247 QQcategoryZ33727QQihZ004QQitemZ140121612735QQrdZ1Q QsspagenameZWD1V

and i believe the only reason i dnt have 1st gear is because of the traction control not working

Not likely. Traction control does not affect shifting or any transmission function. It cuts off injectors and applies front brakes to the spinning wheel. No 1st gear is caused by "A" solenoid failure. followed by no 4th. You can check the solenoid electrically with an ammeter at the plug (or ohmeter 20-30 ohms @68 deg. 8way connector pins E&F. B is F&G. It draws near 1 amp. If it draws right its probably broken. Just pull the pan and you can see it hanging. The speed sensor is easily replaced. It's behind the end cover. Just drop it ( the cradle) down far enough to remove the end cover. Sensor resistance is 1260-1540 ohms.@68 deg. and produces .5 volts @ 100 rpm, 100 v at 8,000 , linear so at 2,000 about 25 volts (AC) It's pins A & B on the 6way connector. Get the FSM its all pretty straight forward. Without it it's hopeless.

i got a transmission i am going to just replace and probably sell the the other one off

does your display say traction control off ?
If so the car will always start in 2nd gear and that would be the problem.

yes it does

Where is there any mention of second gear starts caused by TCS disabled? Couldn't find it in my book under the trans. or TCS sections.

this has been discussed many times cadillacsts2003 actually devised a switch on his etc to make the car still start in 1st gear with traction control off.

From what I can surmise this is true for units built after 93, so BJ's problem probably is this. Thanks

The main problem here is the motor/tranny has to be pulled to either fix your old one or install the used one. This is the major portion of the work, pulling and reinstalling the transmission.

Your other circumstances should decide what you want to do.

If you buy the used transmission, I would repair the shift solnoid, and probably also the A and B shift solnoids, before installing it in my car. Otherwise, at 100,000+ miles, at any time you could be at the same place you are right now.

Are you going to try to do this yourself?

If so, can the car be down for an extended time, or do you need to quickly get it back in service?

If you are doing it yourself, and can have the car out of service for a while, just repair your current transmission and don't spend money for another tranny.

If you are paying for it to be done, I don't see the need for an 'extra' tranny, I would repair my old one.

I think you are actually asking if you should buy a used tranny, about the same milage as your current one, do nothing to it, and have it transplanted 'as is' into your car. This doesn't seem to be a good approach to me, as you will end up with a tranny that could have the problem as you currently have, at any time in the future.

I agree with LCLCLC. The only time I would replace the transmission is if there is major internal damage and the replacement parts are off the board. Then I would rebuild the new one. The only way you will ever know if the new one is good is to take it apart. I've been repairing automatics for over 45 years and 90% of the time without replacing a hard part. Your problem appears electrical. Relpacing all the mechanical parts with those of unknown origin doesn't appear to be reasonable. Especially when the new one will have all the same old electrical parts just as likely to fail as your original. There's also still the possibility that your old input sensor isn't the problem. Try a new PCM about $150. at Rock auto, 30 min job. I replaced the pcm on my 93 ELDO N* because of engine running problems and the new PCM told me the line pressure regulator was bad, it shifted hard and jerked. Yet the old pcm had perfect transmission operation. The third PCM works perfectly. Unless you can perform the diagnostic to prove the sensor bad, you are shooting in the dark and it's an expensive shot. You need to find a knowledgeable and honest N* expert and let him fix it or at least help you. The N* is a masterpiece of electronic control technology where the engine and transmission function together as a single entity. It takes one with specialized knowledge to effectively repair one. There are too many pieces at too high a price to use the old try this method.

Exactly !!!
Find someone knowledgeable to help you diagnose the problem correctly.
And dont just start changing out parts because someone else said they had a similar problem and this or that is what fixed it.

All advice here in the forum is a guide line to help in diagnosing.

i hooked the trans connector to a scope at school and did test on it the sensor is bad i already got the other transmission and i plan on having it tested and replacing w/e need to be place as others said if it isnt broke and is easy to replace fix it later.. i will be doing my self also..

Love it when I hear about the kids in shop class working on Cadillacs......

Ya know there is a reason why the vehicles that are "Learned" on in class are donated.....?
Its because they are pieces of crap as it is and are there for "learning" on.

Your in school and learning all this ???? OK then.
Go for it and have fun......
Its not like its your car and its a Cadillac or anything.......Dohhhhhh......

BTW ? What input have you had from your teacher.....if any ?? Im assuming he doesnt want anything to do with it.
Even though he is the most knowledgeable one in the shop LOL.

Good luck my friend..

he's the one that told me to get the other transmission for one also and so have others on this forum ... why be an ***whole about it .. ?

Oh and removing the trans on those is not as tough as they made it out to be. Support the engine and remove the trans from underneath.
They did that with mine on my 94.

he's the one that told me to get the other transmission for one also and so have others on this forum ... why be an ***whole about it .. ?

And others on the forum have also said not to.
Sorry if Im a bit older and have been in shop classes and have also had friends with there own kids in shop classes and even know shop class teachers.

If your gonna be a smart assed little punk that asks for others advice even though he already has his mind made thats ok with me.
But if you get advice and dont like it shut your punk face and cut out the name calling.

Been there and done that. Grow up.....

yes i asked about a week ago for one.. and for two people have already said to get it i figured it be ok to get it.. yes i would rebuild the old one but i dont know shit about transmissions and i dont have 1800$ for a rebuild.. sorry about the name calling just in a pissed off mood lately lot of shit going on.
thanks for the info i would rebuild it or try to fix it but i wouldnt know where to start.. if you do take me that way or what do you think i should do with the new one. cause i am willing to listen i dont really have my mind set. i really dont want to do this but no money to fix it and i have help from here and others..

............... sorry about the name calling just in a pissed off mood lately lot of shit going on.
........................

Dont sweat it. Id be a lyin sack of shyte if I was to say Id never done the same.
Sometimes its alot easier to let loose in a forum than at home, work, or any where else. And to tell the truth its probably better to get it out here than any of the afore mentioned places. Its done and no real damage done. And if any one has a clue then they will understand..... Not saying to use this as an area to release LOL :stirpot:...:halo:... Anyways

Youve been given some very good and solid advice on the previous page.
Looked to me as the most logical thing to do in your situation. Almost a no brainer really.
You want to pull a tranny to put in another used tranny. There is no guarantee what so ever that the replacement will not fail with the same problem..........Or even something worse for that matter ?????

To fix the problem with your existing trans you would have to pull it anyways ???? Or woulkd you ??? Im thinkin all you would have to do is drop it. I dont believe you would even have to take it right out.

So if your ready to go so far as to replace what you have....Its really a no brainier to just fix what you have. The most complicated part of replacing the solenoid is getting access to it. Once the tranny is out/or down enough to access, its all gravy from there.
Dont make this harder or more expensive than it really is.

When it really comes down to it. The problem may be only as simple as a solenoid. Not a whole transmission.

So this is what the others already said............And it really is the best venue to follow.

And with help forums like this. The best knowledge is personal real life knowledge. So please come back and tell how it all worked out. It will end up in the archives and in the search area for anyone else to be able to reference to.


The main problem here is the motor/tranny has to be pulled to either fix your old one or install the used one. This is the major portion of the work, pulling and reinstalling the transmission.

Your other circumstances should decide what you want to do.

If you buy the used transmission, I would repair the shift solnoid, and probably also the A and B shift solnoids, before installing it in my car. Otherwise, at 100,000+ miles, at any time you could be at the same place you are right now.

Are you going to try to do this yourself?

If so, can the car be down for an extended time, or do you need to quickly get it back in service?

If you are doing it yourself, and can have the car out of service for a while, just repair your current transmission and don't spend money for another tranny.

If you are paying for it to be done, I don't see the need for an 'extra' tranny, I would repair my old one.

I think you are actually asking if you should buy a used tranny, about the same milage as your current one, do nothing to it, and have it transplanted 'as is' into your car. This doesn't seem to be a good approach to me, as you will end up with a tranny that could have the problem as you currently have, at any time in the future.



I agree with LCLCLC. The only time I would replace the transmission is if there is major internal damage and the replacement parts are off the board. Then I would rebuild the new one. The only way you will ever know if the new one is good is to take it apart. I've been repairing automatics for over 45 years and 90% of the time without replacing a hard part. Your problem appears electrical. Relpacing all the mechanical parts with those of unknown origin doesn't appear to be reasonable. Especially when the new one will have all the same old electrical parts just as likely to fail as your original. There's also still the possibility that your old input sensor isn't the problem. Try a new PCM about $150. at Rock auto, 30 min job. I replaced the pcm on my 93 ELDO N* because of engine running problems and the new PCM told me the line pressure regulator was bad, it shifted hard and jerked. Yet the old pcm had perfect transmission operation. The third PCM works perfectly. Unless you can perform the diagnostic to prove the sensor bad, you are shooting in the dark and it's an expensive shot. You need to find a knowledgeable and honest N* expert and let him fix it or at least help you. The N* is a masterpiece of electronic control technology where the engine and transmission function together as a single entity. It takes one with specialized knowledge to effectively repair one. There are too many pieces at too high a price to use the old try this method.

alrite but i have to replace my oil pan gasket so the tranmission is coming out.. i may add the other reason i was looking for another transmission it shift really hard and some times jumps forward really hard when put in to gear

The hard shifting could be from a motor mount and have nothing to do with the transmission itself. Check the mounts for cracks and breaks before you assume it is the transmission.

As I believe I mentioned earlier Mine did this after replacing the PCM (refurbished unit) other likely cause is the TPCS transmission pressure control solenoid. It's located on the side (upper control valve body) midway up on the right. The resistance should measure 3.5-4.6 ohms. 0 current draw produces maximum line pressure, 1 amp produces minimum. the code is PO76 on the older OBDC I don't have a table for the ODBCII. The current draw of the TPCS is an output of the PCM (PD74 on the older) so you can read it directly. With a scope you can see the TPCS signals. The HIGH input is 292.5HZ Pulse width modulated based on load. The Low (GND) is on-off to provide instantaneous response. If a picture is worth a thousand words, a scope image is worth a million.

where are the A and B shift solnoids, and how hard would it be to replace the input speed sensor

The shift solenoids are on the bottom valve body. All you have to pull is the pan and valve body. The valve body must be separated from the lower channel plate and there are 4 check balls that are sitting on top. The FSM shows all this in detail. The valve body should separate easily without hurting the gasket. If the gasket is not perfect it should be replaced which means removing the accumulator housing with 4 more check balls. Alignment of the gasket and bodies is critical. There are factory tools for this but of course no one has them. Just take your time and install all bolts gently and loosley until all bolts can be wiggled equally and the gasket is free and lines up perfectly everywhere. You also have to use a long stiff shim like a big ty-wrap (I forget what I used) to hold the low reverse band in place on reassembly into the case.
The input speed sensor requires removing the end cover and also the transmission side cover. I believe its not necessary to dissassemble the pump or upper valve bodies just the side cover. The sensor is between the two drive sprockets and the book is vague as to whether the chain and sprockets need to be removed but I believe they just slip out with a little gentle prying (the sprocket bearings are a snug fit.). The sensor mounts with a single bolt but it looks like the whole wiring harness is fastened to it. There is probably a plug somewhere close. Someone else here bound to have already done this. I believe I saw Ranger has done it.

Not I. The farthest I have been into a 4T80E (or any trans for that matter) is dropping the pan.

There is a step by step with photos at this link http://www.cadillacforums.com/forums/cadillac-tech-tips/38769-input-speed-sensor-p0717-replacement.html?highlight=input+speed