MK4 Tiptronic VW Transmission: 3rd gear disappeared, but reappears when it is raining

Maintenance/Repairs
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1

OK. I have a 2002 VW Jetta 1.8T with that weirdo tranny (09A for those in the know) with the psuedo manual tiptronic transmission. I don’t think the tiptronic has anything to do with this, but here’s my problem.
3rd gear has gone missing. The car will over-rev high in 2nd and then BAM into 4th (and not, using the Tiptronic does not ameliorate, nor does using the 2nd to 3rd to 4th on the automatic shifter). Interestingly, when doing tiptronic the car will reflect on the dash that it thinks it is in/going thru 3rd, but obviously is not.
HOWEVER
When it rains, 3rd gear re-appears.
I would not say things shift like a dream, but certainly not like the aforementioned nightmare. Up shift and downshift occur on time with an occasional hard shift.

My thoughts are that this is due to solenoid(s) conking out. VW says it is lifetime ATF and makes changing it next to impossible for an ape like me.

Anyone been here? Any idears? Is it definitely something (solenoid or something else?)?

THANK YOU IN ADVANCE!

2

Sounds like a screwy electrical connection to me.

3

sound like a cheap and obvious “screwy electrical connection” by chance?

4

I would start with the wiring connector at the transaxle. Remove it, clean all the contact, and reconnect.

5

Now I will let my ignorance shine:
Is this just a single wire that energizes the transmission? Any idear where it/they is on a MK4 5 spd tiptronic?

6

I don’t know it specifically - never looked at one. But there should be a fairly substantially sized main plug with a pretty big wire loom going into it. These are often located toward the top of the transmission someplace. But there will also likely be some smaller plugs on there for various sensors. The first thing I would do is just get it up on ramps or stands and do a through visual inspection, especially of any wiring that is toward the bottom - where it might get wet. If I saw nothing then I’d pull and clean every plug I could find.

7

About 15 years ago I had a somewhat run down luxury car with “cornering lights” The one on the left was corroded so much it was impossible to remove and normally didn’t work… except when it rained or was very damp outside. Apparently enough moisture and the poor connection that caused it to fail would be completed. Once it dried out, no more light again.

Like others have said, I think this is an electrical problem and your transmission is doing something similar to what I experienced. I would start by thoroughly inspecting the electrical connectors to the transmission and associated wiring for corrosion, tightness, and water intrusion.