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Discussion Starter · #1 ·
2008 T2 Lux Pkg with factory push button start

I learned a few years ago that once a year in sub zero weather the vehicle will not start by push button or even putting the key in the ignition and turning. The only solution was to pull the leads from the battery to reboot (something) and it starts right up. What a pain.

Now...

This winter we are barely getting to 35F and twice now the push button DOEST START but it WILL START if I use the key in the ignition switch.

Anyone have a clue onto what is going on here?

The first problem mentioned made me think the security between the fob and ignition not happy in cold weather but the 2nd part has me confused. I know Vw will have no clue with this issue that cannot be repeated in the lab.
 

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2006 V8 Touareg AIR, nav, hid
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The kessy (button) uses a separate security system then the ignition switch.

Every touareg has the basic key start. The immobilizer just reads a transponder on the key to determine if the touareg starts or the immobilizer kicks in.

The push button switch (kessy) is much more complicated and the security system that it uses is separate and runs in parallel to the key start.

So, it is possible in theory that one system could fail and the other system still operate.

It could be so many things. It will require a vcds scanning the correct blocks to start ruling things out. First thing to test / monitor is the push button switch status. It should show as open (off) when not pushed. It should show closed (on) when pushed down. The ideal time to test it would be when the system is cold and the vehicle is refusing to start.

Now, if the car sees the switch was closed, but does not start, then chances are there will be some codes set. We can start from there.
 

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Discussion Starter · #3 ·
I do have a VCDS (wireless) and use the less functional (iPad) to pull and reset general codes. This concern has NEVER thrown a code. I'm going to assume blocks when done a windows laptop show live values and thus know the open/close status when pushing the button?

So thanks for the in-depth take on how it works and what could go wrong and how best to test. Is there a knee jerk reaction that this occurs regularly and it tends to be reason "x" or are we discussing a fairly unique failure for those who are around here quite a bit?

I've often wondered if there is a relay that doesn't like the cold in the push button assembly but I'm not seeing such an animal from my random searches.

At 175K miles I'm wondering if this will be my last year or if I'll try to ride out the T2 to 250K+ and solving this concern may be the defining reason. I just cannot let the wife drive it in the cold winter because her and 99% of the techs out there couldn't get to the battery even knowing I leave all the tools/sockets todo it!
 

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Discussion Starter · #5 ·
You can still scan the modules for error codes (Autoscan or individually) with the iOS app.
Thanks, that much is pretty much understood do but the part is not clear to me is what he talking about is looking for value triggered and if so can that be done via iOS? (I don't think so) and if not how does one figure out which does what with blocks. For non VCDS nerds this is the hard part to figuring out advanced stuff.
 

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Sorry. You talked about pulling "general" codes, so I thought you were talking about OBD II codes.

I have a small tablet running Windows 10 that I have VCDS and TunerPro (for GM tuning) installed on. Yes, you need to Windows VCDS program to delve further into output tests and measuring values.
 

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2006 V8 Touareg AIR, nav, hid
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I am not 100% sure what the problem is. This is a new one. I don't remember hearing of it before.

Ross-tech is pretty helpful if you are a registered user. If you can post your VCDS scan up to Ross-tech, you can ask how to monitor the push button start and for any other obvious things to check.

Look at post #4 for how to test the switch. http://www.clubtouareg.com/forums/f43/keyless-start-button-wont-work-71782.html Also notice that this person had a constant push button no start problem, but found a wire was loose in the harness.

If it is both the key and the push button, then there is a possible problem with the kessy unit itself.

Things like the engine position sensor and the crankcase position sensor can cause no starts, but the engine will still turn over.

A brake switch sticking or going bad can strop the engine startup routine. Normally you will get the press brake to start notification, but I believe that it is possible for the notification to not pop up under certain failures. If you keep having a problem, I would test the brake switch under extreme cold weather also.

That is everything that I can think of at this time. Hope something in this helps.
 

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I have also encountered this problem in my v8 t2. Thought fob battery so that was replaced but still again when it gets colder I have to put the key in and turn to start. My 12 optima I traded in was also push to start and never had any issues with it in the winter. Wondering if anyone has an answer yet?
 
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