I've done some reading, but have found this error. Previously, the transmission threw a P0748. The transmission is slipping while engaging 1st gear.

My solution so far was to lower FMC values for low torque sections of the FMC tables in order to signal more pressure to the PCS, and the transmission no longer slips into 1st. I'm aware that this is a temporary fix as it shouldn't be slipping to begin with. It has been suggested that an accumulator seal can be to blame for this.

Right now my biggest concern is this P0742, because when it goes off, the transmission goes into limp mode and its very annoying to drive.

People are saying this can be a bad or stuck TCC switch, bad internal or engine wiring (which I will be testing), or a stuck/clogged PCS solenoid.

I'm planning on bringing this car into the garage to fix the above outlined problems. I need all the help I can get here. If I do drop the pan to replace the filter and gasket (which both need to be replaced), I will be be lowering the entire engine and trans to get the side cover off as well.

While I'm in there, what should I replace? Should I replace all of the solenoids? Should I replace the pressure switch manifold? Should I remove the valve body, and if I do, is there anything else I should replace as a preventative measure while I'm in there?

I'd like to have all of the information and all of the parts I need before I begin with this.

I just realized something. Is it at all possible that I've set the pressure too high and that its causing the TCC to stick on?

How can we help you if you haven't done the testing we suggested on the wiring/soleniods to determine if you need to go into the sidecover?

I'm ready to help, but don't understand how to do so.

And yeah..sorry for being a bit of a jerk, but this morning there'* a multithread for one issue bonanza going on and you joined the Koolaid drinkers. =0)

It started with the PCS solenoid, and I tested that already. The wiring to the PCM is good, the solenoid'* resistance is within spec.

I haven't yet tested the TCC solenoid for the same thing, but I'll be able to get to that today. Some of this is second nature for you guys, but not for me. I'm just learning about transmissions, so its still all fairly new. Also, this new TCC stuck code is very intermittent. Its not a constant code. It will go off randomly one day and not at all for another 2 days. I set the pressure back to stock settings in Utah while driving from LA to Chicago this past weekend, and it didn't go off at all the whole way here. Yesterday I decided to put the firmer tables back on because it was slipping into 1st, and it worked fine all day, till today on the way to work I got this code again. I can't tell if the pressure is at all even related. Lowering the FMC values to raise line pressure is also something I had not attempted in the previous thread, but the simple fact is that it works, and I thought that it might be of some relevance that it does work for those who know something about transmissions.

The only thing I have left to check as far as the slipping into 1st gear issue is that accumulator (is that what is called?) seal(*) when I drop the pan. I want to be prepared to have to go further if I find nothing wrong, which is why I created this thread.

Just a side note, it seems that this guy is having the same problem:

https://www.gmforum.com/1992-1999-91/tranny-swap-rebuild-options-293078/

If you manually shift in to 1st, do you have the same slippage? The problem cal also be worn clutches. When you drop the pan look at the magnet. Also, take out the shift modulator and open that up. It'* right there so you may as well check it. Check for smooth shiny cylinder walls. If you have that, sand with some 400 grit just to scuff it up. Inspect the O rings. I've seen adding a shift kit remove slipping mainly because it engages faster.

If I manually shift into 1st, it doesn't slip. It doesn't actually "slip" at all if you will. It just doens't engage 1st gear. You can sit there and as you accelerate, it will not have 1st engaged until it will just..."pop" into place and all 1st gear will engage. Once you are in 1st gear though, it doesn't slip.

I'll take out that shift modulator probably tonight and take a look. I suppose dropping the pan isn't that big of a deal.

I'll also look through that shift kit writeup and go ahead and do that as well. I'll report back once that'* done, although it still doesn't explain this P0742 code.

That'* not really a slip you just described, but a bang start.

http://www.tripleedgeperformance.com...ts__P0742.html

What your describing isn't the modulator. That sounds like the forward band. The solenoid to engage that is on the rear of the transmission near the diff cover, a little to the left of the cover. You will see what looks like a cup mounted on the back of the trans. 3 bolts I believe. Now, taking it off is a bit tricky. There'* a spring behind the cover. So as you back off the bolts it'* going to start coming out. Inside there is a piston with a rubber O ring. I think I would start looking there after dropping the bottom pan. Watch for any chunks in the pan.