D2 gearbox scare (A8L 2000)

johnny_quattro · #1 21st April 2016, 10:10 AM

I was on my way to a funeral of all things last week, and had the car washed prior to attending. On my way there from Surrey to Hendon, North London - my gearbox went into limp home mode (all lights illuminated on dashboard, namely PRND432). I was rather unimpressed as I'd only had the gearbox done at great cost (£3K) in April 2014. To add to my woes, the range on petrol sank from 55 miles down to nothing in no time at all, due to the added revs to keep the old girl moving.

I had to pull in to get petrol, and thankfully when I started the car again there were no errors on the dashboard. It all seemed to work perfectly. Another couple of miles down the road, and PRND432 lit up on the dashboard. I made it with 3 minutes to spare, thankfully. On the way home, it did the same again on two occasions. Each time, I pulled over and did the IT thing and switched the engine off and back on again. It seemed to be some sort of electronics fault as I didn't get the so-called 'bang/whoomph' when selecting drive.

The next day and every day since that fateful moment have been OK. No further occurrences. I have a sneaking suspicion that this could be due to water ingress in and around the area under the bonnet on the right hand side close to the windscreen. I do have a weird error on the car where it seemed to show the brake drum icon prior to the gearbox fault showing up, which again ties in with my hunch that it's possibly due to water getting in somewhere. I think that the two events are related (I've asked my friendly Eastern European friends to be a bit more careful when washing the car as they do seem to be over-zealous with the jet wash lance.)

I'm hoping to look at the car over the weekend and will report back with my findings. An initial look under the bonnet showed the tell-tale white lines of where water once sat and has since dried up.

Note - scan using Torque app on Android and Bluetooth ELM237 shows no fault codes at all.

The_Laird · #2 21st April 2016, 10:24 AM

You need a scan - urgently!

Could be the infamous F125 switch, but you would have thought that might have been sorted as part of the gearbox work. But a scan should show it up. Also, pop the cover off the electronics box at the back of the engine on the passenger side and look for signs of water in there. I recently had all sorts of electronic glitches that were down to a poor seal on the lid of that box.

johnny_quattro · #3 21st April 2016, 10:28 AM

Thanks for that info. I'd read many threads and saw some of your reported troubles, which I think pointed me in the right direction - much appreciated. I may approach Adrian E to see if he can assist with some freebie VAGCOM goodness.

Cheers,
John G

The_Laird · #4 21st April 2016, 10:43 AM

Or search the VagCom register on this forum for the nearest person to you

Adrian E · #5 21st April 2016, 02:48 PM

Hiya

I'm about most of this weekend if you want it scanning

I would be opening the e-box under the windscreen to check for water ingress - I would otherwise suspect F125 switch, but since you're linking to a recent wash that'd be the first port of call for me if there's no fault codes stored relating to F125.

Usually when the F125 switch plays up it's when you're moving between P-R-N-D and once up and running it's unlikely to play up on that basis

The lack of mechanical noises/symptoms also points to water as the potential cause.

The seal on the e-box can get weak and there's a multitude of ECUs in there - the gearbox one isn't the lowest though, from memory.....

steamship · #6 21st April 2016, 04:16 PM

Quote:

Originally Posted by Adrian E

The seal on the e-box can get weak and there's a multitude of ECUs in there - the gearbox one isn't the lowest though, from memory.....

Correct. The ABS is the lowest ECU, although there is still a bit of room below it. It almost sounds like my MOT failure recently, as I was a tad over enthusiastic with the pressure washer. Managed to get a puddle of water in the electronics box, as well as dousing the internal electrics as well, through Botang's hole. Since mine sits out under trees 24/7, there was grit stuck at the back of the electronics box which I didn't see, and so didn't have a good seal.

Hoping it's only the F125 switch.

johnny_quattro · #7 21st April 2016, 04:54 PM

It's all coming together quite nicely. Thanks chaps for all of the invaluable input.
There have been no physical problems with the gearbox and what with my seemingly connected circular brake drum type graphic on the DIS, I have a feeling that we've got a swimming pool's worth of H2O in there.

Wish me luck with the screws as I've seen some posts detailing a frustrating time trying to get the lid off. My penetrating oil (ooo-errr missus) might come in handy. Not as handy though as Mr Adrian with his laptop ;-)
Adrian - thanks for responding. I've still got your number so will text/call to arrange and see if we can sort something out.

Adrian E · #8 21st April 2016, 05:36 PM

I've had the gearbox ecu out of mine before and it's pretty straightforward to access from what I remember.

I took mine out to test one for a friend!

steamship · #9 21st April 2016, 11:41 PM

Quote:

Originally Posted by johnny_quattro

... and what with my seemingly connected circular brake drum type graphic on the DIS

Missed this in your first post. Do you mean this icon:

http://www.volkswagen.co.uk/assets/c...ring-light.jpg

If so, that is the brake pad wear indicator. Did that only appear after the car wash, or have you seen it lit up before? If you've seen it before and it's intermittent, it could be a break in one of the leads to the brake pads. If it's been on ever since the car wash incident, it's either the brake pad HAS actually worn down and activated it, or there's possible water ingress into that connector as well.

The sensor has a circular connector with two pins in it, and should be secured with a spring clip. The clip on one of mine was put in wrong, so it was just sitting there. It looks like this:

http://www.audipages.com/Tech_Articl...akesensor3.JPG

johnny_quattro · #10 2nd May 2016, 06:41 AM

Thanks for your reply! Lots of good info there.

I've checked under the bonnet and it all seemed dry as a bone in the electronics box at the NSF by the windscreen/scuttle panel. I couldn't see any high water marks but just to be sure, I think I'm going to have to take that box apart and double-check all the electrical connectors. That will be a job for when I'm next off work.

With regard to the brake pads, they were replaced a while ago on the front and I know that the brake wear indicators are only present on the front and NOT the rear. I know it's a generic icon but since I'm such a pedantic old sod, it does annoy me that the graphic shows a brake drum when the car clearly has discs all round. I will get the garage to check the front brake discs/pads this week as the light still keeps coming on. No fault codes stored when scanned with Android 'Torque' app & ELM237 bluetooth OBD dongle. On a related note and with reference to a recent post elsewhere on this forum, I've ordered an OBDEleven dongle from Lithuania with the PRO application - seems to be excellent, according to the reviews I've read.

Thanks again.

P.S. No further gearbox issues, touch wood.