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This transmission shifted smooth and strong through all gears until today when it stopped all of a sudden to engage either Drive or Reverse. No previous signs of slippage, hesitation, stalling or lack of power whatsoever.
We checked the linkage to the transmission and it works as intended, nothing loose or broken, everything is in place. If there was something slightly different with it from other similar vans we have then it had a slightly delayed engagement in Drive (it took a second to engage it after you moved the lever) – on all other vans we have the transmission go into Drive almost instantly.
Van is a ’92 Pontiac Trans Sport/Chevrolet Lumina APV with the 3.1L V6 Chevy TBI engine with the 3T40 automatic transaxle.
Any idea on where we should start tackling this issue?
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Does it move in manual 1,2, and/or 3? When engaging drive it shouldn’t take more than a second for most transmissions. If there is a pressure tap on the transmission I would start there. Plug a pressure tester into the tap and check the transmissions hydraulic pressure through the gears.
Sounds like either the fluid pump is broken the input shaft is stripped or the torque converter has a broken roller clutch inside.
It doesn’t do anything regardless of the lever position (R, D, 1 or 2) – it’s like there’s no linkage/command on the transmission.
Checked the linkage and it’s there & working but the transmission won’t react to it in any way… No engine rpm change in gear, no movement, nothing.
Silly question. You did check the fluid right?
If the level is correct, I’d do a pressure test on it. And then I would drop the pan and inspect it for broken internal linkage re: the main spool valve where it connects to the actuator/shift linkage.
If the transmission has zero pressure, fluid is good and at correct level- Then I would stick the fork in it and call it done. Even just sitting there at idle you should have some considerable pressure.
S-
I double-checked the fluid, everything’s in order there.
Is there any pressure/test valve on this transmission?
Dropping the pan’s probably a good idea at this point. Figuring out if this is an easy fix or not is my primary concern before putting too much money into it.
The main spool valve doesn’t seem so tough but if we have to dissasemble the whole drivetrain to get to it then it would be wiser to just swap the transmission with a known good one.
Sounds like you don’t have pressure or something with the manual valve is broken. You can indeed check the pressures to find out if the pump is working. I don’t know if you could rent those or not. You’ll also need to know what service port to hook into. There are normally several on a transmission that all go to different circuits in the transmission. You might consider doing that before dropping the pan. I don’t think you’ll find much, but if you find a clogged filter that could explain the issues as well.
More info on problems like this here.
http://www.ericthecarguy.com/faq/solving-transmission-problems
Keep us posted.
It seems we are all in agreement here. Do a pressure test. Like Eric said you will need to find out which tap in the case is the pressure tap and rent out a tester if you don’t have one(try autozone!) At idle there should be some pressure. Reverse and First gear should have anywhere from 160-200 psi and the rest of the gears should have pressure as well. Usually not as much as first and reverse. Now… the best way to do this test is on a lift so you can rev the engine to attain a vehicle speed. This can be dangerous if not performed properly so do so at your own risk. 30 Mph is as fast as I’d go on the lift(use common sense and proper lift saftey techniques). Also, make sure that the pressure tester is not leaking or you will run the tranny dry(use teflon tape if you have to).
pray that those suggestions fix it because if not, on that car it’s often an internal transmission problem.
Definitively solved the problem by swapping the transmission with a known good one.
Now the TCC has gone south (it comes on ragardless of speed, stalling the engine).
Does anyone know how to fix it without too much hassle with taking the subframe and transmission down again?
I wish there was an easy fix, but follow the quick check I have posted below…(underlined)
I have the diagnosis in a GM service manual, but I found this in the internet. It will take a while to scan the service manual so try this first. I remember the transmission turbine shaft to the torque convertor seal damage doing that. A quick check for that is remove the torque convertor circuit connector (side) of the transmission and test drive to see if the torque convertor is still locked up.
http://www.a-body.net/forums/showthread.php?58-Replacing-Your-Torque-Converter-Clutch-Solenoid
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