4T60-E Gearbox Problem

I live in the UK and am the proud owner of a 91 Trans Sport.

Currently 500 miles from home and have an annoying problem with my gearbox which I'm told is a 4160-E.

Problem is that when kickdown operates it refuses to return to the high gear until I stop and restart. I'm not looking forward to driving 500 miles back home in 3rd gear and there's no one here who can help.

I believe kickdown is operated by a vacuum solenoid rather than cable?

Can anyone please tell me where to find the solenoid and whether I can safely disable this for my return journey - I have 3 weeks before I need to go back to the UK.

Thanks.

Some confusion here...'91 had only the 3.1 engine with the 3T40 3 speed transmission..at least in America. ...or you have a '92 with a 4 speed 4T60..in which case running in 3rd gear as an emergency procedure back home is not a problem. given the very low axle ratio. HOwever, running the 3 speed in 2nd is not confortable.
"kickdown" from "high" gear (3rd or 4th depending on transmission type) is simply a downshift to the next lower gear, and it is accompanied by release of the torque converter clutch...
Applying of TCC after the 3rd gear (with 3T40) if feeled by many as a 4th gear, though it is not.
IN all cases, solenoids are internal to the transmission...not something one wants to intervene far from home. THe modulator might be the culprit with the 4T60....
WIth the 3T40, there is a transmission cable linked to throttle ...this cable could be binding when you pull it to the end by depressing full throttle and then it keeps transmission from shifting back to high gear....

Thank you for replying so quickly and I'm sorry for the confusion over the vehicle year. I have a 3.8 engine so we must be a '92. I made an SOS call to the place I bought the car from and and they've confirmed the 4T60-E gearbox. I presume it's going to be an expensive job to get this fixed if it's internal? Can you tell me if a vacuum tube goes straight to the gearbox or does the vacuum activate an external switch (is this the modulator you referred to)? In either case as a temporary measure could I disconnect the vacuum? Operation of kickdown is (and I think always has been) very sensitive and needs little pedal movement to activate it. I don't believe in coincidences but neither can I imagine any logical connection but I'll tell you anyway - at the same time as this started the oil pressure guage is playing up with erratic fluctuating readings. Forum messages tell me this could be the sender or a bad ground. Is there any way this could be linked to the kickdown problem? To complete the picture - We have another easy to live with problem that when the car's been standing for a while it takes 20 to 30 seconds for drive to engage. Fluid level is OK and I've been told both fluid and filter were changed as part of the service before I purchased vehicle. Gearchange is OK but not as snappy as I've been used to with British cars. Mileage????? well the clock shows 58,000 miles and the vehicle is in impressive condition but I'm not sure I believe it.

I appreciate your help.

Thanks once again.

Yes the modulator is vacuum activated but disconnecting the vacuum from the modulator is the equivalent of applying full throttle...hence not a solution. The have been a few cases here where this part was a culprit in similar or neighbouring circumstances.the fact that the car was "prime" on kickdown could point in the same direction.
www.avigex.ca/xport/modulator.jpg
check rockauto.com for info on this part and price.
you can vaguely test the modulator action by disconnecting and connecting the vacuum while car is at idle: no vacuum increases transmission oil pressure and this generally translates in the transmission pump buzz increasing somewhat in intensity. reconnecting the vacuum lowers the buzz...but this can be barely perceptible.
HOwever more severe problem is not ruled out....
Ground problems are frequently reported....and I would suggest tracing some ground wire and splicing a new ground wire to a clean ground spot on the engine and frame..just in case. Corroded grounds running under the floor carpet under driver's feet have been identified as culprits in several cases..

Thank you once again. I will follow your advice but I guess there's not much I can really do before I get back to the UK. It may be a while before I can get this sorted out but I will eventually let you know the outcome.
Best regards
Martin
UK

I'm sorry for asking another question but I'm hoping you can help yet again.

The like for like replacement of my Vacuum Modulator is an AC Delco unit part no. 8662967. This is available off the shelf both in the USA and Europe so I can obtain one of these within a few days. However this unit appears to need an additional "Valve" (AC Delco part number 08658375), not supplied with the modulator and only available by special order from the USA.

OEM alternatives (tempting if only because of the cost difference) make no mention of the "Valve".

Can you please tell me what this valve is, where to find it and what it does?

Thanks once again.

Regards

Martin

..yes modulator and modulator vale are both mentioned in the diagnostic list for various problems. YOu can change the modulator without changing the valve....that must be the regulating part of the contraption acted on by the modulator piston. ...Most modulator problems are from the blown diaphragm and do not involve the "valve".
...in fact the "modualtor" actuator is a quite simple device, bell, diaphragm and spring....I can't see how Delco figures out around $100 for that...
THe Delco modulator is quite expensive, compared to others as I can see in the list at RockAUto.com ... so unless I have some positive test , I,d rather try the less expensive alternative I did not have to change mine yet ; the hint I signalled is part from logic and part for the tales of others .

My UK dealer quoted over $400 for the Delco part but there again he charged me $35 for a single headlight bulb until I knew better! I've ordered an OEM plus the valve and am hoping it will all arrive in time for me to fit before my return trip. I'm tempted to take a close look at the current unit but don't want to risk making things worse.

Will let you know how I get on.

Regards

Martin

It's taken a long time to get my 4T60-E problem fixed but the least I can do is to complete the story:
I have no idea why but changing the vacuum modulator seemed to fix the problem, but only for a few hundred miles. When our local specialist garage dismantled the gearbox they found many components, hardware and software, badly damaged. It took us a long time to locate the parts here in the UK but eventually we found them, rebuilt the unit and we're back on the road.
Thank you for your help.