Transmission vs. ECM

[ulremember]

Hello to all.
I am back with another question. My transmission is still not shifting properly. No 1st sometimes. 2nd gear starts sometimes. No OD all the time. 3rd sometimes.
Now here is what I found I could do. Unplug the ecm fuse for about two hours and I get my shifts back 1-2 2-3. Tries to go into OD, but the common complaint still exists- slipping out of OD.
Now could it be the transmission or the ECM. I spoke with a ECM repair place and the gentleman stated " it sounds like the ECM due to the fact it is getting VERY warm to the touch and I cannot manually control the gear selection. Says there have been problems in the past. My rig is a 1994 2500 4x4 with the 7.4 CID. Remember, NO CODES anywhere that I can pull. A while ago I hooked up a Modis Scanner by Snap On and my truck went into limp mode right away. This is back when I had 1-2 2-3 shift but no OD. I am curious as to why the tranny will shift for various lengths of time when I disconnect.
Thank you in advance
Blessings
Chuck Butler Jr

[pgutierrez]

Chuck,

I have the same problem!!! I have a '92 Suburban K1500 4wd 5.7 CID. I have no OD at all, the shifts are in the 3K range from 1-2 and 2-3 and this sucks. Please fill me in and what to do or change. Any help would be appreciated!!!

Paul

[longslide]

it kinda sounds like 2 problems at the same time. the no od sounds like a tranny problem im not sure what tranny you have but it odds are its either a 700r4 or the 4l60e. i just had my tranny rebuilt last week and it was having the same od issue and then the r went out. the od issue was in the electronics ( i have 4l60e ). the other shifing problems sound like the ecm. might just be bad luck or timing with the od thing.

[ulremember]

Hello
I have researched and researched! I have dropped the pan a couple of times. all of the solenoids check out to be good. as for the OD, I believe it could be the tcc solenoid. I have read that the bore becomes worn and will not hold the converter in lock up or something like that. Have you checked your speed sensors? My tranny is the 4l80e. I do not if they are the same as the 4l60e. Check all of your ohms readings for the solenoids, change the fluid and clean the magnet. Make sure your cooler is flowing properly. I spoke with a ECM repair place, and they stated that there has been instances when the ECM goes and creates problems like this. He said since I cannot control the shifts manually, he is suspecting the ECM. Suggested that I get one from wrecking yard to check it. Money is soooo funny, it is laughing at itself. could be a bad valve body also (worn or dirty/clogged).
If I find the exact cause, I will reply back.
Dieselplace.com is a very good forum also regarding these transmission. Look for Genbilstien's post. VERY knowledgeable and helpful!
Blessings and good luck!
Chuck aka ulremember

[ulremember]

Also, inside of the ECM, there is what is called a "quad module driver". It controls the solenoids by completing the ground circuit. They go bad. ALSO CHECK ALL OF YOUR GROUND CONNECTIONS. could over work the circuit and then it goes bad

[GarShar]

I kind of have the same problem. I have a 1994 K1500 Suburban with the 350 700r transimission. I get a code 43 wich is the code for the knock sensor. I have replaced that but still I get the same code even after clearing the codes. The thing has no power and I have to manualy do the shifting to start off in what seems to be 2nd gear. I also have no overdrive. any suggestion?