Ok, have a 1996 Plymouth Grand Voyager, 3.0 motor, 3 speed auto trans, has 195K on the clock.

Trans was rebuilt in 2003 at 128K by a professional trans builder. Engine runs good, has a few oil leaks, but otherwise still strong. The torque converter always had a shudder in it, I just learned to drive it like that. I would let off the throttle to let it lock up & if necessary give it more fuel to unlock, then lock back up. Trans shop added some additive that helped for several years, but then it came back a few years ago (2010). I haven't had to add any fluid to it since rebuild as the levels always remained where it should be. I was told to only use Mopar/Chrysler ATF in it.

I know, I know, I've been very lucky.

My problem started last week, trans wouldn't downshift to low gear unless the gear selector was moved to the "L" position. Then it would drop down. I checked the trans fluid, level was ok but the fluid was dark, not red. No burned smell, just dark colored.

I changed the fluid & filter with Valvoline ATF+4 last Saturday and after about 30 miles of town driving, the downshifting problem went away. It's dropping into low when I come to a stop, drops to second gear when slowing to turn a corner & will downshift/hold the shift if I stand on the pedal. It shifts fine in other words, just like it used to. Except for one problem.

That problem is the torque converter doesn't seem to lock up like it did before. I don't have a tachometer on the dash, so can't exactly tell if the engine is slowing down. I've had it up to 60mph driving & it seems to not be locking up. I'm thinking this will resolve itself with a few more miles on the filter/fluid change, but I want to ask first.

I don't have any codes, so I think (there I go again, using the noggin & search function) the torque convertor lock up solenoid is working properly. I'm thinking the fluid passages were just gummed up & it will just take a few more miles to get the TC to start working correctly. If that doesn't do it in about 100 miles, I'm thinking of giving it a shot of additive, but need a recommendation. I have also read to not use an additive in ATF+4. So, the questions.

Sorry for the long winded post. Any help/advice is appreciated.

 

Oh I forgot to mention, I just pulled the pan, swapped the filter, added a drain plug. The plan is to add a aux trans cooler in a couple weeks, then after 1000 miles change the fluid again. This way, I get up to 80% of the old oil out & the trans will work as it's supposed to.

The cooler will be put in because of the heat here in Yuma.

 

Take a look at the plug going into the transmission case, near the dip stick. Make sure it is plug all the way in. That plug is for you lock up solenoid.

 

I will check that tomorrow after work. I don't think it's out, as the shifting problem started all at once. I had an intermittent downshifting problem about 3 months ago, then it went away. I think the fluid change fixed the shifting problem, now to get the TC to start locking up. I'm also thinking the fluid change just needs a little bit more time, but I'll double check the plug-in.

 

If you have a problem with lock up converter, you would have set a transmission code 37.

 

No MIL light, I'll double check to see if there is a code hidden there.

Much appreciated.

I wonder if I'm just so used to the shudder I've had, that the new fluid doesn't let it shudder & I'm just missing it. I'll see if I have an old Sun tach I can hook up temporarily to see if there is drop in RPM after 45 mph.

 

Ok, no MIL light, plug on side of transmission is in place, I'm not quite sure if the lock-up converter locks up or not. I think it does, but without a tachometer, I'm not sure.

I've drove it around 150 miles & it seems to be getting better, so maybe the fluid change helped it. Still shifts a bit late when first starting out (cold), but after the first shift it shifts just fine. Both up & down. So I'm thinking it's been fixed.......... for now.

Thanks for the help.