4L60E issues; slipping OD?

[Lazerbeans]

First of all wonderful site; lots of great info. I have a 1994 C1500 GMC Suburban 5.7 TBI, I am having issues with. First glance it kind of appears its slipping in OD. If you are running 2500rpm to maintain speed, it drops to around 1000-1500 when you let off the gas. It shifts at around 2500-3000rpm, and that’s it, no other shifts. If I run through gears manually, they all show none of the slippage, except OD. I switch from 3rd to OD and hear a very soft shift back and forth, but the rpms don’t drop when going into OD. The rpms actually rise a little going back and forth, then settle down to what they were, the same either manual 3rd or manual OD. If I leave in in D or 3rd, no slip, rpm’s drop a little as normal, when letting off the gas.
With the background and symptoms the best I can describe, here were I am at. It is throwing a code 82, and nothing else. Which is 2-3 shift solenoid, which makes sense with the 3.42 gears. Sounds like it skips 2nd, goes into third, and maintains around 2500rpm at 55-60mph, which with stock 29’ tires is about right, and doesn’t lock up or go into OD. My overall question does all this make sense? Would a bad 2-3 solenoid, make it act this way? Or am I fighting a bad 2-3 solenoid and maybe a bad TCC solenoid or something. The 1-3 shift (I guess) is solid, just higher than I understand it’s supposed to be.
Thanks ahead of time guys

 

[Lazerbeans]

I am surprised this has you guys completely stumped. I figured someone would have some kind of input. I guess I will post what it is when I figure it out for FYI.

 

[DGA1]

If I were in your shoes, I'd do the work myself. I'd replace the TCC valve with the upgraded one and the 2-3 solenoid. With the fluid and a new filter this will run you less then $100 and you don't have to take the transmission out. Even if it does not end up being either one and you need a transmission rebuild, because you might if you don't get on this soon and it's one of those two things, you'll still know that you replaced one of the most problematic aspects of this transmission...the TCC valve.

http://us.ebid.net/for-sale/7577384...oogleshop_us&gclid=CNDCi6G_pbgCFQHZQgodBFUAsQ

http://www.amazon.com/Acdelco-24230298-Automatic-Transmission-Solenoid/dp/B0065QAB6Q

 

[rhino]

I am not sure of what it is exactly doing? Does it have 2nd gear at all? If it has no 2nd and no 4th, change the shift solenoids.

 

[Lazerbeans]

From what I understand 2nd and 4trh are interconnected through that solenoid. So skipping 2nd and have no 4th makes sense. I do have manual 2nd, so I am going to start with that solenoid and see what happens. The only gear I cannot get manually is OD. The RPM’s don’t drop, but there is a shift of sorts, when manually switching between drive and overdrive. So maybe no lock-up? If it’s that solenoid would it not lock-up, therefore no RPM drop? Thanks for the insight, guys

 

[DGA1]

No lock up could be your TCC valve...any codes, particularly P1870?

 

[Lazerbeans]

I get an code 82 only, even after disconnecting the battery. That's the code for 2-3 solenoid "B" error. Though I have seen on some websites its a 1-2 solenoid "A" error and a crankshaft sensor error too. So I guess I will drop the pan and test both solenoids, and go from there.

 

[DGA1]

They are also cheap enough that since you are in there you might as well replace both. You'll spend more in transmission fluid. I belive they are same part numbers as well. I'd also check the wiring to both while you are in there.