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Discussion Starter #1
Hi peeps, desperately Need advice and help! I have an automatic 1994 2.4 and it has recently developed gearbox issues. First of all it went into safe mode and wouldn't move into any gears unless I did it manually with the 1 to 3 shift, so I replaced the autobox ECU and also the wiring that goes to the autobox. Was working well again for a short while, and now has developed another fault in which it sometimes skips 3rd gear, so goes from 2nd to 4th, which isn't an issue until you get to around 55mph, and then it wants to change up again as ECU detects there's another gear change needed resulting in it going into safe mode, which you have to reset by turning engine on and off, so basically doesn't go past 55mph now. When on the rare occasion it does select 3rd everything is ok, although it sounds like it's slipping when going into 3rd.
Heads baffled and no one I know wants to deal with. Does anyone know of anyone who can help or what the solution is? Would be extremely greatful of any help. Would change to a manual but my girlfriend can only drive automatics so that would be no good. I live in Scarborough. Any help would be much appreciated ?

Thanks
 

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When was the fluid/filter last changed?
You're "early" won't have the lockup in 4th like the newer ones have.
Did you get the correct TCU (not ECU)?
Fluid should be "pee yellow", NOT red, or burnt brown!!!
There's also a "multi-plug" that goes into the rear of the gearbox...often (TOO often) the cables to it break/corrode/snap off!
Only people I recommend are Mackies in Glasgow (I drove from Norway to them with a "spare" box I had to be sorted!)


BTW....don't "care" about your girlfriend...I'd NEVER change to a manual!!!!
 

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Discussion Starter #3
Hi, yeah the multiplug has been replaced, that's what I meant by wiring? as it was corroded like you said, and yeah I did get the correct TCU not ECU? as I got it from a van that was the same year. The fluid is a Reddy brown so guessing not been changed in ages as when I got the van was in poor mechanical condition, so changing that will be my next plan of action, and failing that then maybe a trip to Glasgow!
Thanks very much for your help ??
 

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Is changing the gearbox fluid a big job by the way?
It can be a bit of a pain in the backside. Depends if you have the dipstick or not.

If not then yes, as you need to remove a plastic plug under the starter motor on a tube which is about 2" long coming out of the top of the gearbox.
Once you have the plug off you need a length of tube about 3 ft long which fits over the tube so you can refill from the top of the engine bay.

A simple process other than it's a bit of a got to get the brittle plastic cap off without breaking it and getting the refill tube on is an arkward angle as the starter motor is really close.

To drain the old stuff out you need to drop the whole sump pan off which if 5 or 6 10mm bolts so nice and easy.

Plenty of videos on YouTube just search for VW o1m gearbox
 

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Discussion Starter #6
Ah right, well mine has the dipstick so guess it'll just be a case of dropping the pan, replacing filter and filling up again through dipstick, so shouldn't be so bad then, thanks for that?
 

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Discussion Starter #7
Also does anyone know what the purpose of the plastic dial is on the auto box TCU??
 

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Don't know about the dial, as mine is a 2000 box (so different TCU).
Later ones are "software" controlled for 3 settings.....self learning, economy and "sport" settings...maybe that's what the dial does?
You need VCDS to do the fluid change (and it should NOT be reddish/brown....that is DEXIII and WRONG!) as the gearbox temperature has to be at 40-50C when changing the fluid.
It's also done with the engine running in P.
You fill slowly (through your dipstick) until fluid runs out of the sump plug (which has a tube up inside to get the correct level).
If you've had DEXIII in there, you'll need at least 3 changes with the correct fluid, as the torque converter does not drain...so you end up with still around 20% of the bad fluid in it.
Buy from VW....it's a special fluid (and don't forget you may need a new mortgage to pay for it!).
 

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Discussion Starter #9
Ok, well gonna leave that dial well alone then? . And I'm definitely going to follow them steps as I want it running right as everything else has been done on the van, will be the first thing I do tomorrow, thanks for the advice ?. Just discovered I was wrong about it not going into 3rd though. It is going through all the gears as it should, the only problem I have is when it gets to roughly 55mph 3000rpm it tries to change gear again, almost like it wants to go to a 5th gear that doesn't exist! When that does happen it reverts to safe mode, which is why I confused about loss of gears, when you turn the engine off and on again it's back to normal until it gets to 55mph again and then back to square one. I'm beginning to think that despite the fact the replacement TCU was out of the same year/engine van it might be the wrong one. Who's to say the wrong one wasn't put in the donor van at some point. Will try the fluid change first like you said and take it from there. Thanks again for your help ?
 

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Check that I am actually correct about the filling for your year of 'box.
I only "know" the post 2000 (or 1998, depends where the van was supplied to!).
Maybe with the dipstick you can just keep checking the level?
Also not sure if it needs to be running or not....but you'll have to at least run it for a few mins in P to get the fluid flowing before checking the level...and again, and again...LOL.
I have my "spare" 'box (Mackies refurb) in the garage, and a dipstick to fit to it if/when the current one fails. (Simple job, I'm told.....)

Is the "dial" a variable....or a 3 position switch? (Maybe does the same as software on the later versions?)

Please keep us updated...any info on these delicate boxes is appreciated. (y)
 

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Discussion Starter #11
Hi I managed to change the fluid, wasn't a hard job. Ran it in P until at running temp, removed bolts to remove filter and drain fluid, replaced with new filter and gasket, and topped up with correct fluid through dipstick tube. Did not use DEX111. Unfortunately did not solve the problem but did need a good change so was worth doing. Was thinking I might need a replacement auto box However after nearly giving up and , I discovered a cable hanging down that plugs into the side of the fuel pump, so reconnected it took it for a run and it's running as good as it ever has with no problems at all!! I'm over the moon! Went flying past 60 no probs!! I'm thinking the disconnected cable may have been confusing the TCU. All good now! Only 1 engine mount to replace and the van is perfect!? I did find out what the dial was by the way. It's not a dial as such, it is just an air vent to prevent moisture building up inside the box. It just turns round and does nothing really.
 

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Discussion Starter #12
I am also going to buy another auto box as a spare. I know someone who has just converted a van of the same year as mine to a manual, so I'm going to ask for the box he's taken out as a spare, that's where I got my TCU from etc. Be daft not to as the early 2.4 automatics are getting extremely rare! Mines done 215,000 and has most parts replaced in last 2mths to make sure it's right
 

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Discussion Starter #15
Nice one thanks, good to know as I paid £38 for 5ltrs from Euro car parts. £13 for filter kit. Runs a lot better now, real smooth gear changes and not playing up at all 👍
 
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