Hey to all Cadillac owners! I just bought a '97 Eldorado with 92k and i have ran into a problem. So any info would be a great help. The tranny will not shift into overdrive. It shifts from 1st to 2nd to 3rd smooth with no hard shifting but not od. Took it to Aamco this morning and they wanted to rebuild whole thing at a cost of over 2500! (only paid 2100 for car) After reading about alot of the problems with the 4T80E does anyone think it could be the 3rd to 4th solenoid? I was told by Aamco that it was shifting to od but was slipping (although i have not felt it slip) and that the clutch was failing to stay engaged. Does that warrant a total rebuild? Any help with this would be greatly appreciated. I am on a very limited budget and have finally got a car that i have always wanted and i do not have the money to rebuild the tranny. Thank you to everyone in advance for any help you may provide.

 

When you took it to AAMCO, did they get any codes out of the system? If so, what were they?
If they did not pull the codes, or did not tell you what they were, you need to check for any codes. Check out this thread for info on how to get the codes for your car. Any codes it has will help us determine the real problem.

Both shift solenoids have to operate for the trans to have 1st gear, so...if it has 1st, the solenoids are probably ok. Chances are, the O/D band is burnt, which is a common problem. Usually, if the trans is missing a gear, or slipping, it will set a code in the computer for a "gear ratio error", or a shift solenoid code. These codes will also usually turn the "Check Engine/Service Engine" light on, and depending on what code it has, it may make the trans shift hard.
It may be that the PCM is not commanding O/D for some reason, which could explain not having any gear ratio codes, and not shifting hard. Even a coolant temp sensor problem could keep the PCM from commanding O/D, so ALL codes that the vehicle has are important, when it comes to diagnosing a problem.

$2500 is a normal price for a 4T80E around here. It's quite labor intensive to remove/replace the trans, but the actual building of the trans is not that bad...it's just really heavy, and bulky.

Check for codes first, and let us know what you find, and we can go from there.

 

They did get one code and it had to do with me taking the battery loose. I had to pull the air filter box and forgot to plug the sensor back in. So i took the positive battery cable off to see if it would cause the check engine light to go off and it did. That was the only code they came up with.

 

My only suggestion at this point would be to drive the car around, preferably getting some highway miles in, and them check again for any codes. My post above has a link to a thread here that explains how to get the codes by using the climate control panel buttons. Without any computer/module codes, it's going to be difficult to determine what is going on here. If you drive it long enough at a speed that should induce the overdrive shift, and the shift does not occur, or O/D is slipping, there has to be a code set, OR the PCM is not commanding the shift. If the PCM commands the shift, but the rpms do not drop accordingly within a programed amount of time, the PCM will set a code, usually a gear ratio error or solenoid fault.
If it does not go into O/D, and there are no codes set, then we have to assume the PCM is not commanding the shift. This could be for several reasons, such as a temp sensor fault, a speed sensor fault, or even a malfunctioning MLPS(manual lever position sensor), which could be showing the shifter to be in 3rd gear, instead of O/D.
hth

 

ok after driving on the highway and getting up to speed (55 to 65 mph) it never seemed to shift. the rpm never changed or dropped. it was about 2700 rmp at about 65mph. after coming home i figured out that holding the info button down with the key in run position that it told me "monitoring system ok". so is this how you bring up any codes that it may have? also what about the torque convertor clutch switch or solenoid? thanx for all your help.

 

How to get codes

 

Ok i finally got the codes figured out.
PCM P0603
TPS C1225
IPC B1552
the rest of these codes i didnt write all info down correctly:
B2550
B2107
B2103
B2119
B2120
B0856
B1983
Wasnt sure if i should clear the codes or not. they all had "history". i cleared anyway and took the car for a drive and tried to get codes. all showed no codes

 

Also if this will help; i tried manually shifting and there was no change from 3rd to 4th. it seemed as if it is just staying in 3rd gear as there is nothing at all.

 

P0603 is a KAM(keep alive memory) code, if memory serves. It basically means either the battery has been disconnected for a while, or there is a wiring issue that is keeping the PCM from having constant power o it for the memory function.
The other codes all appear to be BCM related, or Body codes, except the one TPS code, which is for the tire pressure monitoring system, and the ICP(instrument panel cluster). I don't have the other codes available here, but I can post them in the morn.

 

Just have a quick question: is it possible to use a transmission from another car such as a deville or sts with northstar?? also what yrs will interchange and what kind of problems might that create??