4T40E Missing 1st Gear

[miker33]

Hi All,

I am using a Daewoo 4T40E from the Lanos along with a PCS TCM2000 Transmission Controller.

When the car is in D it can only select gears 2-4 electronically, 1st is unobtainable even when using manual gear selection on the TCU via a laptop. You can only successfully use 1st gear if you physically select 1st on the shift lever.
Is this a problem that has been seen before as I have tried 2 transmissions and they both show the same symptom (also tried 2 different TCM controllers and looms to elimninate that as an issue)? I tested both shift solenoids on each gearbox and the resistance is good and you can manually engage\disengage them with a clear click noise as they are engaged so don't think these are the problem.
Is there anything different about the Daewoo version of the 4T40E transmission that would make it behave differently to other generic 4T40E transmissions used in other GM models?

Many Thanks,
Mike

http://www.twinenginemini.co.uk

[RSZT4]

seems like a TCM issue still, did the ones you replaced it with work properly?

[miker33]

Hiya,

Thanks for the reply, in the end I discovered that the 4T40 transmissions seems to override 1st gear when they are completely unloaded in any gear selection other than 1st directly with the shift lever if the wheels are off the gound (I couldn't try it loaded at the time as there was no suspension on the car) but once it was used on the ground it works fine.

Cheers,
Mike

[RSZT4]

So wait, you had the car up on a hoist? and you were testing this?
You might want to add that into your explinations, thats a HUGE thing, your car must be under load for the transmission to work properly.

[miker33]

Unfortunately i've had no experience of working with auto transmissions before so no I didn't know that it wouldn't work properly at the time when unloaded, every other gear behaved correctly apart from 1st. There is virtually no useful information around auto transmissions and people who do know about them don't share the knowledge very freely at all.

When building the car up from scratch (it was a manual before) it was a matter of testing before completing construction of the vehicle's suspension since removal of the engine\tranny is a very large job already without adding the complete removal of the suspension again, as it happened with no reply's after a month I completed the build anyway and it was fine once on the ground.

[RSZT4]

Unfortunately i've had no experience of working with auto transmissions before so no I didn't know that it wouldn't work properly at the time when unloaded, every other gear behaved correctly apart from 1st. There is virtually no useful information around auto transmissions and people who do know about them don't share the knowledge very freely at all.

When building the car up from scratch (it was a manual before) it was a matter of testing before completing construction of the vehicle's suspension since removal of the engine\tranny is a very large job already without adding the complete removal of the suspension again, as it happened with no reply's after a month I completed the build anyway and it was fine once on the ground.

hmm, well there is tons of information out ther about the 4T40E transmissions they were used in many different cars. Theres lots of stuff out there about them, just have to look and search, Glad you didnt pull it all apart again and have found out nothing was wrong. Just for future refrence make sure you add in details it can make someone give you the correct answer sooner.

here are someother links that might help you down the road if needed.

http://www.vibratesoftware.com/html_hel ... ssions.htm

http://spacecoastfieros.com/tech/440-4T60/

http://www.zoom-tech.com/downloads/supp ... /4t40e.pdf

http://www.avigex.ca/xport/4t40_1.jpg

http://www.avigex.ca/xport/4t40_2.jpg

http://www.avigex.ca/xport/4t40_3.jpg

and you must have load on the car to test it, this goes for pretty much all auto transmissions

[miker33]

Hi,

Thanks for the links, I had already got to most of those apart from the Fireo 4T60 one. While i've found loads of base technical data and mechanical construction info the one thing that is missing from most web info is guidance on the low level function\problems of the transmission which is where i've been struggling as there was no baseline to compare since the transmission was already removed from the donor vehicle and I only had the aftermarket TCM-2000 unit so it left me a little in the dark.
Hopefully I can get it all working well now, still having a few issues around the driveshaft RPM speed detection as it only detects around 7-8 pulses per rotation on the controller (i'm sure it should be closer to 30 after counting the teeth on the sensor wheel) where it's showing a clean strong signal on the oscilliscope but will give PCS a call to discuss (it's doing it on both engines\transmissions so don't think there is a sensor problem).

Thanks for confirming my final suspicions about needing load to perform correctly as I thought it was just my imagination at first or I had done something wrong with the installation\wiring

It's so much easier driving a twin engine auto car than a twin engine manual car as the 2 manual clutches used to really wear out my leg in traffic queues.

Cheers,
Mike

[benzino]

twin engine?

W-W-WHA-???