Greetings fellas....I have a 1989 Deville with 4.5L V8 440T4 transmission with 175K + miles on it and I am getting the E39 code. I changed the VCC solenoid and Brake Switch. I have probed the 422 circuit, the 420 circuit powering the brake switch and I have not found any loose connections nor shorts. Here is the big issue, when I start the car and place it in diagnostic mode and monitor the clutch engagement signal on the display (the front defrost symbol) the system operates properly. I can see and feel the engagement of the clutch....usually when fourth gear engages and I can see it unlock when accelerating or when fourth gear disengages. When I come out of diagnostic mode it takes a few moments and then E39 reappears and the clutch is disabled for the rest of drive even when I clear the code. Once I turn off the car and let it sit for about 20 seconds I can restart it and drive it in diagnostic mode without a failure. If I drive it without going into diagnostic mode E39 trips and the clutch fails. My question is; Why does the system operate when it is in diagnostic mode and not in normal mode? Am I missing something?

 

It will NOT set any codes while in Diag mode, regardless of whether or not the converter clutch is working. There are specific parameters for setting the code(s), and just because you may feel the converter lock up doesn't mean it is holding properly within the RPM range the ECM is expecting to see. The trans could be slipping slightly in 3rd or 4th, or the viscous clutch may be worn, allowing too much slip. Try driving it in 3rd gear, and see if the code sets. If it does, the converter is slipping. If it does not, then you may have a different trans problem. With 175k+ miles, my bet is the trans and converter need a rebuild. If you do rebuild, or just replace the converter, go back with a non-vcc converter. Lock-up will be a bit firmer, but it will last much longer. Plus....it's next to impossible to get a viscous clutch converter anymore.
hth

 

Thanks Adam for the reply.

I will try to test the lock up function in 3ed gear as you explained and check the results. When I do use the diagnostic mode, the clutch usually engages (the front defog symbol) when the trans shifts into 4th gear ( the rear defog symbol ). Sometimes it engages while the transmission is in third gear moments before the 3-4 shift.

This is not the original transmission, I am the third owner of the car. The second owner had this transmission replaced with a junkyard pick I think about 2 years ago. When we bought this car in July, he complained about it slipping during the 2-3 shift.

I personally did an inframe rebuild of this transmission in july. During disassembly, I found large amounts of friction material throughout the transmission however I did not find any metal shavings. The second gear clutch pack was worn with less than 10% friction material remaining. I replaced the bands and clutches (metal and friction discs) and the VCC solenoid, reassembled, and the trans has been running nicely except for code 39. I am not a proponent of a soft shift and if/when I replace the converter it will not be the VCC type (I did not know you can install a non-VCC type converter).

I have three questions;

1) Is there a way to measure the lock up hydraulic pressure?

2) is it possible to drive the car with my MT2500 connected to the ALDL and monitor the torque converter?

3) Where can I find the parameters the ECM uses to operate the torque converter?

Thanks again for your valuable info.

 

IF the trans has been swapped, chances are it has the wrong gear ratio, and THAT is what is setting the code. The incorrect ratio will not have the right 4th gear ratio in lock-up that the ECM is expecting to see. You need to determine what the original ratio for the car was, and then determine what ratio the trans that is in it now has. You can find the trans ratio by looking at the white Service Parts code label on the car, usually found on the bottom of the spare tire cover, sometimes on the underside of the deck lid(trunk lid), possibly on the underside of the center console lid...no telling where they put it. For the trans, there should be a metal tag attached to the trans case, passenger side/rear, towards the pass side axle.
You can certainly drive and monitor trans data with the Snap On scanner attached. Not sure you'll be able to look at TCC slip data, tho, on a 440T4, since it does not use an input/turbine speed sensor. The ECM uses the engine rpm data, along with the vehicle speed sensor, to determine the ratio, and if it thinks the TCC is slipping or not. In 3rd gear lock-up, the ECM should "see" a 1.1 ratio. If you can drive it in 3rd, and the code does not set, you either have the wrong ratio trans, or something is slipping.

Afaik, you can only put a pressure gauge on the TCC release side.





Ignore the red boxes and text in this pic...that info is for someone else

 

Thanks Adam for setting me straight on this Trans. Everything you suggest is correct and I remember reading said info during my research. I forgot about the ratio match between the ECM and transmission. The car came with a final ratio of 2.97 (F79) and I will search for the transmission gear ratio identification.

To give you an update, I did drive the car in 3rd gear for about 20 miles and it did not set the E39 code during the entire drive. When I went back to overdrive, sometimes it would set early (a few seconds) or at times it would set after 5 or 10 miles. I also tried to make it slip during 4th gear lockup while climbing uphill grades, which it did not set until I got on a flat.

I will try to gather some data from the MT2500 (RPM, Trans Temp, etc.) to determine if something is slipping during normal driving conditions.

 

UPDATE:

The Transmission ID plate is missing the bar code sticker and the only info stamped on the plate is the day, year, and shift build date ( 026, 3A, 05 or 06). I am guessing; 26th day of the year 1985/1986 and shift 3A.

My ATSG maintenance manual lists only one final drive ratio for Cadillac years 1985 thru 1989 and that being 3.33. I got my 2.97 final drive ratio from the GM Production Options published Feb, 1997. Interestingly enough, this GM publication does not list a 3.33 transaxle final drive ratio.

Looks like I may have a puzzle on my hands.

 

I'll check my info/charts tomorrow and see what ratios were available. I can bet you that there was more than just the 3.33 for the Cadillacs.
The trans ID could also be a paper/plastic tag on the side cover, if it's still there, and readable. It would only be a 3 alpha/numeric code, such as your F79 Service part code. Unfortunately, those things don't survive very well in the elements....

 

Can't beat Adam's info! He just save me from installing a good 2001 DeVille tranny (Code 9) into my 2000 SLS (Code Y). Not only was the ratio different...his post was the only one which mentioned the Neutral Switch change. Thanks Adam for sharing your first hand experience/knowledge.
Read a step; Do a step; Get a banana. (:-)