Just had tranny rebuilt due to slipping. Everything working great but noticed after a few days tranny not shifting into 1st gear when coming to a stop. Took it back to trans. shop to explain problem and they said mech. tran. ok and put the problem on the ecm. Took it to another tran. shop and they verified it to be the ecm. Shifting from 2,3,4 is ok and strong. Problem is not consistant i.e. sometimes it shifts fine and other times no first gear. Started looking for refurb ECM and was told it was my tcm that may be causing the problem and not ecm. Any help is trying to solve the problem would be helpful.

 

You only have one computer (like most Rams even the newer ones) and everything is built into it. So your PCM (ECM as you call it) has your TCM in it. So you need a new PCM

 

Trans control portion of the PCM rarely fails though........ (usually its IAC control, or voltage regulator, occasionally a driver for the coil/an injector) I would more suspect that when the trans was rebuilt, they didn't change the electronics, and that's where you problem is. (governor pressure sensor/solenoid.) Cheaper than a PCM too.....

 

There is a trick you can do to test the electronics, you describe it best. Can't type that much on my phone without sounding like chiberish 😂

 

Only because I have typed it so many times.... I should start a document with 'tests' I suggest on a regular basis, so I can just copy/paste. My fingers would thank me.

In any event.....

On the drivers side of the trans, about halfway back, is an 8 pin connector. Unplug it. This disables ALL the electronics in the trans. (and yes, it will set a host of codes.....) Go for a drive, bearing in mind you will have ZERO automatic function on the trans. You will have to up/downshift when appropriate. (and you won't get TCC, or O/D either.....) So, start in first, and shift when you need to. If the trans shifts into the gear you tell it to, when you tell it to, you have an electronic problem, that should be able to be solved simply by installing new electronics. if it still exhibits undesireable behavior, you have a mechanical problem, and the trans will likely need to come out. (or, go back to your rebuilder.....)

 

To be honest I thought you did copy and paste it

 

Nah. That would be a 'smart move', I can't possibly do that......

 

Same here man, same here

 

Ok I have disconnected 8 pin and took truck for a test drive. Unable to manually shift into 1st gear shift lever in 1 gear position but transmission is in 2. No problems shifting from 2 to 3. With 8 pin connected truck will start off in 1 gear initially but once i make one or two stop/starts reverts back to not shifting into 1 gear. Turn truck off transmission will repeat same shift pattern 1 gear but then after stop/start a few times shifts down only to 2nd gear.

 

You have an internal problem then, time to go visit your rebuilder.