Torque converter lockup

'92 rodeo with RWD and the 4L30-E automatic. The thing runs like a champ, even with a cracked radiator, hardly even breaks 200F. Problem is that the torque converter will not lock up in D. works in 3 just fine, and will work in D if i pull back ever so slightly on the shifter, checked the linkage for a misadjustment, and even backed it down a hair, no change. after about an hour of driving it will stay locked up without holding the shifter but if i hit a bump on the highway, it may or may not unlock. was thinking solenoid, but it really can't be that simple can it? possible TCM problem? help!!!

How many miles you got on this rig? Sounds like you've maintained it really well, but what has your maintenance interval been with the fluid change outs?

I know my '91 Rodeo, which you confirmed also had the 4L30-E tranny had a transmission dipstick, which made it easy for fluid swaps. I'm not sure if your '92 has the dipstick though - my '97, with the same tranny, has no dipstick, which makes it a pain in the arss.

yeah i've got just under 80,000 i've been to iraq twice and my wife has been out of state for the deployments, so unfortunatly it has sat for a couple years, i change fluid and filter every time i get back, and yet the problem remains exactly as it has. i'm leaning towards an electrical contact problem (sort of like the one you can get with a blower switch only working on 3 out of four settings or only working in that in-between area, i was just looking for a second opinion before i started tearing the transmission apart. i try to keep up on the truck, but its keeping me busy. i've just replaced the carrier bearing 2 u-joints and both collector gaskets. in the future i'm going to need a gearbox a little bit of bondo and i'm looking into buying a locker for the rear end (as its cheaper than buying a transfer and front end). i've also got the same ALDL bit... i've worked around many older model vehicles, this is the only one where i still haven't located the ALDL, and i my check engine bulb took a poo on me and won't light up anymore so i'll have to rip the dash apart to change that someday too. not too concerned, i make about 23 on the highway as an average.

First and foremost, I want to thank you and your wife for all that you're doing, I can't even fathom how hard that is, in going to Iraq and being separated from one-another. My hats off to you and your wife :thumbsup: and may faith bring you both home always.

Do double check for any electrical gremlins, other then that, I've got to be honest, I haven't had any tranny issues to assist.

23mpg is great!

Wow - 80k miles, I've got almost double.