Daewoo Questions


Mon, 26 Sep 2011

Daewoo Reviewed by lobe on .

Hi,The auto gearbox ( Aisin Warner 50-40 model auto gearbox ) ...

Hi,The auto gearbox ( Aisin Warner 50-40 model auto gearbox ) will not shift out of 1st into 2nd etc. This problem occured after girlfriends 15min drive on the motorway/freeway, after exiting on down ramp coming to an intersection, then wouldn’t 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.  Wouldn’t shift from 1st. Thrashed it 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 well 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 at 1st opportunity i.e when exiting highway/slowing down at intersection etc.

Accelerating high into rev range causing car to then shift gears only worked for say 3 – 4 times. Now non shift from 1st problem is permanent.

Scan showed fault codes - for cam sensor, crank sensor park neutral switch (in memory from older problem).
1.       Cam, crank sensors replaced with new. Park neutral switch disassembled and checked - ok.
2.       ECU/ TCM (trans control module) wiring checked, connections etc.
3.       Batt disconnected for a few hours to clear ECU.

CEL still on. Problem still persisted

4.       Fit 2nd hand  TCM, SOME SUCCESS –  CEL off. Suspect this has been cause of CEL been on for ages. Transmission still won’t shift though.
5.       Tried 2nd hand  ECU with no success - transmission still won’t shift.
6.       Park neutral switch disassembled and checked - ok, nothing obvious.
7.       Check gear shift cable and adjustment, park neutral switch setting – all ok.
8.       Suspect throttle position sensor, disconnect CEL light came on immediately. Reconnect clear ECU.
9.       Inspect wiring to park neutral switch, gearbox temp sensor – all appear ok.
10.    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 doesn’t shift into 4th when in D and hence not suitable for motorway, highway driving etc.

**** Next is to drop pan inspect for solenoid short on wiring etc. If solenoids are at fault, why would gears still shift using above method outlined in 1a, 2b, 3c ?

Any ideas, help would be appreciated Thanks.

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