Mk5 gti electrical nightmare

What's the battery voltage like the rest of the time? Defintely worth having at least one BM2 bluetooth battery monitor/logger. It's fairly short range on BT V4, but it only uses 1mA and stores up to 35 days syncs with an app. They only seem to be UK stocked at amazon at the moment.

 

Excuse my lack of knowledge I'm used to mk1&mk2 golfs (I know where I stand).
What is the canbus gateway is it a plug.
A data box,I'm clueless lol.

 

No worries!

Here’s the guide GVK posted. Take the battery off before removing it, just see if there’s any corrosion or damage first

 

For testing, you can get any gateway module (of the same part number) and plug it in and the car will start, it will need coding though to your cars options/features.

You really need some diagnostic equipment to be able to do this job i'm afraid.

From what I know if the gateway is completely buggered the car won't start and doesn't allow for any comms to the scan tool, which yours obviously does as you have the codes from matey's Launch tool.

Quick check on ebay shows can gateways for between £10 and £35, you need to get the part number off it first though.

 

So the situation was when problem first occurred the car would still start but just before the ecu was removed for checks the car got worse it would start and die immediately.this box with the red plug (position unknown)but led to beleive its between pedals and scuttle.i suspect this box may have water in it wouldnt surprise me at all.so just to refresh me is this a control
Gateway module/box thingy.if wet its toast
And will need another.but correct me if its changed things/systems will start to communicate then interaction can take place
With programming through the odb or am I talking twaddle or somewhere near.lol

 

Check the link Nates2 posted of mine, on the GTI mk5 there are 3 possible positions to the gateway module.
Get the part number (starts with 1k0) get a gateway module off ebay. Plug it in and see if it starts, should start the car without coding.
Yep if it's wet it's scrap!
Yeah can be programmed (coded) with VCDS via OBD. I've never coded modules with VCDS so i'm not sure how to advise on that. Obviously you need a pukka version of VCDS for a start though (£225)

There are you tube videos for coding and threads with info on mk5 gti.co.uk You have to do some research.

 

Ok thanks think it could be that.lets.gope so
As I've found 2 for sale at a yard near me
One ends code 930e and the other 930f
Think it could be one of these with luck.so when this gateway is plugged in car may lose
The ability to start becouse of the imobllizer
On gateway will have to be synced with ecu
And a few other bits I'm guessing.
Bloke who initially looked at car has got an upto date bit of kit.but he never mentioned this gateway at all perhaps he not aware of it.
This is where I'm heading for next anyway

 

I theory it should start I think, it will just have a load errors because the Gateway doesn't necessarily have the write modules coded to it to match your car, and will probably have component protection activated because again, its not aware of your car. Ideally you'll get a huge amount of errors still but they'll be different once they've been cleared.

ECU is just Engine Control Unit, Mk5's have an ECU for the engine and lots more control units for, Instrument cluster, ESP, ABS, Airbag, Radio, door, etc. These all talk to each other through the gateway, and hence the gateway has to know which modules your car has to work properly. For example, not all cars have handsfree, but if yours does, then the Gateway needs to know about it, this goes for all modules on the car. Hopefully, your broken Gateway is working enough to get the coding off it transfer to the new one.

Try and find someone with VCDS, really the only tool thats going to give you an accurate picture of whats going on and allow coding

 

Ok sort of understand but no signal to ecu would indicate nothing is getting past the gateway correct??
It's of now and I've had and looks to me like no sign of water damage that's not to say it hasn't failed although I cant see any burnt bits on this board.

 

It looks ok visually, but you never know if any of the components have failed.

Was a recent post on mk5 golf gti.co.uk where the gateway had failed and he just plugged another in and it started, as I have said previously it will need coding to the car but should just plug in and run for testing purposes.

As nates2 posted ideally you need vcds to code the module, erase faults etc.

 

Ok just get another to see if any different
Not like it's much money.i am out of my depth with this sort of thing but dont mind
Unplugging stuff and trying new stuff but that's where it ends for me really.if I plug a different one in does immobiliser come into play on a different one?I sort off get what your saying this unit is unique to this car but some systems will just work correct???

 

The coding will tell it if its dsg or not, that kind of thing.

I'm only going by what I've read elsewhere on if it will run or not, I've never used vcds to code anything either.

If you plug another gateway in , you still need to remove the faults from the last scan , but from what i've read the car should run.

 

The immobiliser components I believe are the cluster, key, and engine ECU. The gateway I don't think has any play in that part.
The Gateway handles diagnostic and relaying signals between the 3 CAN buses, so if it goes wrong at all it can cause a huge variety of errors across modules on all buses because they aren't seeing data they expect.
Clearing the faults its very important, might be worth clearing them with your module too just to see if that helps. Once faults have been logged like that the modules have limited functionality until their cleared.

 

Got another gateway module from a local breaker.and is the same part code down to the last letter mine ends 530f and that's what Ive got.some I saw just end with different letters like "e" but the numbers always seen to be the same just a different final letter at the end.spend some time on it tomorrow.
Tested ecu is also back now too.
And confirmed as not faulty.

 

They revised the gateway part number due to battery drain issues with certain stereo units, so you can fit a later(final letter) one no problem.

Have you got any way of clearing the faults?

 

Today I refitted the tested ecu.fitted the replacement gateway and the car started.
And the sun was shining happy days.
Then the auto electrician just happened to drive by while I was playing about.he was on way to a job.told him what I'd done.he said
He quickly throw his vagcom on and see.
He cleared all the faults.then he said now the
ECU is getting messages let's try the old gateway again.changed it and well I never all is working(he cant explain it)
But has said keep the other gateway and if it happens again he,l code it in for dsg etc.early days but the car is working.
Thanks all for your pointers something has sorted but dont understand what and neither does he.

 

Great that it's working but they are the worse kind of faults that can't be explained.

At least you have someone that should be able to code it should it play up again.

 

I should be pleased I kind of cautiously am.
But would prefer to find a definite fault then I would know its rectified.as it cant really be explained the concern is it will reappear at the wrong time.maybe it wont.done a few short bursts in it 1 or 2 mile and that's it then back home.got learn to trust it again lol.
Have ordered a new Bosch s5 battery today from tayna.should come tomorrow or sat.
As i/we dont know the car that well and the battery was trickle charged all last night.
(Did that make a difference)who knows!!
So the battery not so much on this but I've had duff batteries in the past that have done weird sh+t to cars so taking no chances.
It's the good one 770a 75ah I think decent anyway.car even looks happy or am I seeing things lol.

 

Fingers crossed all the work has sorted it, nice car.

 

Daughters not mine lol.
Gone from a 1.4 75bhp polo to this.
Must feel like a rocket to her.
To be fair the dsg gti is a quick car.
And I'd have too but having a mk1,mk2&a bluemotion passat something would have to go and that would be harder than buying a mk5.