94 Buick Century Wagon transmission problem

[cbrownmt]

I have some questions on diagnosing a problem with a transmission on a 94 Buick Century Wagon.

3.1 liter
fuel injected
auto transmission 4T60-E( I think, not verified)(it has 1st, 2nd, 3rd, and overdrive)
Mileage on it is approx 157,500.

Symptoms: Service engine soon light on. Vehicle sometimes hesitates during take off from a stop; seems to shift later than expected; will not go into first gear.

A few weeks ago while trying to diagnose the problem, I first serviced the transmission, which is a 4T60-E I believe(20 bolt pan). Prior to changing the fluid, the old fluid was brown and smelled burned. The filter was also replaced at this time. An oil/filter change, air filter replacement and new spark plugs were also done. After completing this work, the car seemed to run better, but the Service Engine Soon Light was still on, and although the car did not hesitate as much from a stop, it still had delayed shifts and did not seem to go into first gear. After some more research, I decided to try and access the trouble codes from the data link connector (DLC). I read online how some vehicles can have the trouble codes read by using a jump wire between terminals A and B. However, I also learned that some 94 and 95 model vehicles do not have a terminal B and if so, a scanner would be required to access the trouble codes. It just so happens that the 94 Buick Century is one of those vehicles. So when I found out a friend of mine had one of those GM code readers, I got all excited thinking I would be able to diagnose and ultimately solve the problem. Ironically, the 94 Buick Century is one of those vehicles not covered by the GM code reader. I believe it is a GM code reader 1.6.

So here are my questions:

Can another code reader read the codes on this vehicle? Or is a scanner necessary?

Is there another way to access the codes without a reader or scanner, such as the jumper wire method without having a test terminal on the DLC?

After changing the transmission fluid, I realized the new fluid still smelled somewhat burned most likely because the old fluid that remained in the torque converter mixed with the new. Should I change the fluid again and try to remove the fluid from the converter? If so, how do you get the fluid out of the converter?

I verified that the correct transmission fluid was added and that it is currently at the correct level. After much research online and in the Haynes repair manual on the vehicle , I have found many possible causes including the transmission modulator. A hole in the diaphragm would certainly indicate all of the symptoms this vehicle has, but the transmission doesn't seem to be losing fluid and no white smoke is coming out of the exhaust. I have thought of removing the modulator and doing a vacuum pressure test on it but do not want to replace it unless I am sure it is bad.

One other note, after realizing the GM code reader would not work, I removed the ECM fuse for a minute to reset it hoping it would remove any trouble codes and run properly. And when I test drove it, I put the car in 2nd gear and punched the accelerator to the floor. It did go into 1st gear one time, but then after coming to a stop sign and taking off, the Service Engine Soon light came back on and the car did not seem to want to go into 1st gear again.

I hope to get some advice on what steps I should take next and will be waiting eagerly for a response.

[DanD]

If like you said that you have a 12-pin connector for an ALDL (Assembly Line Data Link) and the B terminal is empty then yes you need to use a scanner to retrieve codes.
94, 95 and 96 model years were the transition years from OBD-I to OBD-II and GM was playing some pretty goofy games when it came to diagnostics. Your friend’s code reader must only be OBD-I compatible.
Even if you get the code(s) what are you going to do with it, it is vary rare that a code alone will tell you what is wrong.
Scan data along with the proper test procedures and a host of other test equipment is what’s going to take to repair this vehicle and then that’s only if it’s solely an electrical problem. (Not likely)
I shouldn’t say it’s not but with you saying the fluid is burnt, I think you’re going to end up pulling the trans for a rebuild.
There are so many variables to cause this, that in my opinion, you’re going to have to take the car in and have it diagnosed by someone that is familiar with the operation of the system(s).
Sorry I wasn’t of any help with an easy fix.
Dan.

[way2old]

There is an adapter that is needed to read the codes on your vehicle. It makes the ALDL compatable with an OBDII scanner. The only way to drain the torque converter on your vehicle is to remove the converter of have a transmission flush. A GM dealer may be your only recourse to have the codes read. We purchased the adaptor for our shop cause we had 2 S-10's that we could not read. Good luck. Hopefully it is something stupid like an engine sensor reading off causing the problems. The modulator should not be expensive and is easily replaced. So any scanner will work f you have the adapter installed. If you have a friend at GM, they may read the codes for ya.