Daewoo Leganza 2.2L Auto. Won't shift in D. Only fault code is U3F00 ???

lobe

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Hi,

Sorry for the waffle (below) but the history might help someone smarter than me help with this problem. Suspected serial data link, comm link problem. Only fault code when read with snap on OBD is U3F00 ???, it just re appears when cleared ???

******
Daewoo Leganza Oct 2001 2. 2L Auto. Australian model. Transmission won't shift from 1st when shifter is placed in 'D' ( can be operated like a semi auto so is drivable - see last couple of paragraphs )

The trans ( Aisin Warner 50-40 model ) will not shift out of 1st into 2nd, 3rd, 4th in D. This problem occurred after girlfriends 15min drive on the motorway/freeway, after exiting on the down ramp & coming to an intersection, then wouldnt change out of 1st. I picked the car up 3hrs later, disconnected battery for 5mins, checked trans oil level after warm up, then drove car. Wouldnt shift from 1st.
Thrashed it abit in 1st round near top of rev range and it shifted gears. Auto trans working again. After 15 min drive back down freeway, same problem.

Check Engine Light (CEL) had been on for ages prior to fault ( suspected cam sensor ) so difficult to say when a suspected transmission fault problem occurred, other than physical problem of it failing to shift from 1st.
The ATF oil was not burnt but i flushed it anyway, inc disconnecting cooler line to empty torque converter of old oil etc.
Replaced with new ATF. Still the same problems - stuck in 1st gear, accelerating high into rev range in car caused it to shift again, but after brief drive at highway speed, transmission would stick in 1st after slowing down at intersection etc, when the trans shifted down upon slow down but would then not shift up as speed increased.
Accelerating quite high into rev range causing car to then shift gears only worked for say 3 4 times. Now non shift from 1st problem cannot be cleared by just accelerating high in rev range.

Scan some showed fault codes - for cam sensor, crank sensor & park neutral switch (in memory from older problem, since replaced).
1. Cam, crank sensors replaced. Park neutral switch disassembled and checked - ok.
2. Batt disconnected for a few hours to clear ECU. CEL still on. Problem still persisted

3. Disconnect batt. Clear ECU. Fit 2nd hand TCM (transmission computer) , SOME SUCCESS no CEL on. Suspect this has been cause of CEL been on for ages. Transmission still wont shift in D. Tried a 3rd TCM just to be sure, same result - no success.
4. Tried 2nd hand ECU with no success - transmission still wont shift in D.
5. Park neutral switch disassembled and checked - ok.
6. Check gear shift cable and adjustment, park neutral switch setting all ok.
7. Vehicle speed sensor appears Ok, as speedo is working ok.

Note : The vehicle speed sensor did fail about 3 months prior to trans shift problem, resulting in speedo not working. Transmission still worked as normal. Sensor had failed mechanically. Replaced with brand new OEM part. Speedo worked again.


The car can be still driven, by using the following method, to allow it to shift like a semi auto, as per owners manual.
1a) pressing the hold button down on the gearbox, put gear/shift lever into the # L position - gearbox holds 1st only.
2b) Move gear/shift lever into #3 position - gearbox then shifts and holds 2nd gear only.
3c) Move gear/shift into D - gearbox then shifts and holds 3rd gear only.

This method is ok but obviously doesnt shift into 4th when in D and hence not suitable for motorway, highway driving etc. Transmission is actually capable of getting 4th gear - by disconnecting trans computer completely - i. e then it has obviously gone into limp mode (L holds 1st, 3 & D hold 4th as per owners & workshop manual)

Only fault code when read with snap on reader is U3F00 ???, it just re appears when cleared ???

Trans valve cover removed & shift solenoids checked. All operate ok. All ok with resistance check. Wiring harness inside trans checked for continuity - all ok.
Continuity from TCM pin 11, to OBD/DLC pin 2 all appear ok. Ok from tcm pin 11 to ECU pin B13 ( serial data link between tcm/ecu ).


Any ideas, help would be appreciated
Thanks.
 

billr

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#2
I'm refreshing this for you, since I know it can be frustrating to get no reply. Maybe putting it back up at the top of the stack will help; but truth is, Daewoo isn't a very common brand in our North American market. Let's hope someone recognizes the Aisin trans you mentioned from another, more popular, application.
 

lobe

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Thanks mate. Any help is appreciated.

A few were sold here in Australia, prior to Daewoo going under etc but when it comes to fixing them, most people don't wont want to know or just simply 'dont know'. Its far easier to fix a Ford Falcon or a GM Holden.
 
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#4
I can't find specifications, but you should test the input speed sensor. It's behind the 'left transaxle bracket'. Perhaps you could compare ohms values with the output speed sensor (which may also function as the Vehicle Speed Sensor).

A shift solenoid problem would be my next guess. I once made an axillary shift solenoid harness with indicator lamps to light whenever a solenoid had power. 1 light for 1st, 2 lights for 2nd, no lights for third. Light comes on but no shift= bad solenoid.

A one-way clutch problem would be my third possibility.
 

lobe

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Thanks,

Input and output shaft sensors or signal failure problems should throw fault codes P0717 & P0722.

I have the workshop manual for this car with all the wiring diagrams, and ohms values to check etc, so i'll give your recommendations a try.
 

billr

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#6
Have you had any new good luck identifying that "U3F00" code? If it remains a mystery, it might indicate the PCM is hosed, or at least it's memory is corrupted and needs to be re-flashed. Good luck with that...
 

lobe

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No luck with finding out any info on that code yet, including posting on a few other forums too.

Note: I did try another ECU/PCM whilst i was at the car wreckers sourcing a used replacemnt TCM for the transmission. Neither the ECU nor TCM made any difference to the problem. I also tried a 3rd TCM to be sure i hadnt replaced the original TCM with a second TCM from the wreckers which could have also been faulty ( a long shot i know but still possible )

Thanks
 

billr

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#8
Lobe, you probably already know this, but maybe it will jog the memory of someone else: it looks like that trans was also used by Volvo, Saab, Opel, and Saturn; much more common brands here.
 
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#9
Went on a Daewoo /Europe site and found all of the table options codes on the Daewoo, from A to Z, and there ae a lot of them. According to the code listed "U3F", the code relates to "Display Language-English". According to the tables it has nothing to do with the transission or any other diagnostic codes. I know the code reads U3f00, but that is just finishing out the code with zeros to finish off the 5 digit code. I guess the snap on scanner is telling you it is sending out information in English and not Korean.