Engine start

[Mikel]

Hi all I am looking for help. I own a8 d3 2007 3.0tdi my issue is that I cannot put car just for ignition, like fir scanning. As soon I press start button engine start even without brake pedal pressed. I change for bew beake switch, there is no fault in vcds, I try with key also as soon as you move key to right engine start again without brake pedal. Measuring block shows brake switch working and showing pressure also. Could someone help me please 🙏

[ainarssems]

How about putting gearstick in Drive, that should stop it from starting

[Mikel]

Originally Posted by ainarssems

How about putting gearstick in Drive, that should stop it from starting

Thank you I will try that. But I eventually I will need permanent solution so trying to sort this out

[Adrian E]

Is it possible the brake pedal interlock has been disabled in coding? Might explain it.....

[MikkiJayne]

The D3 has an engine authorisation and start module doesn't it? Not my specialist subject obvs, but I'm sure I've seen it in the diagrams. Maybe try and get a scan of that - perhaps it is faulty and does an engine start on power-up instead of actually waiting for the start command?

[Mikel]

Originally Posted by MikkiJayne

The D3 has an engine authorisation and start module doesn't it? Not my specialist subject obvs, but I'm sure I've seen it in the diagrams. Maybe try and get a scan of that - perhaps it is faulty and does an engine start on power-up instead of actually waiting for the start command?

The car start as soon you press start button or turn ignition with key

[HPsauce]

Originally Posted by ainarssems

How about putting gearstick in Drive, that should stop it from starting

Not necessarily, it depends what is wrong.
When my D2 S8 (OK a different, earlier and simpler model) had problems starting it was identified as a faulty F125 switch. Shorting out the relevant relay that inhibits inappropriate starting, overcame the problem.
BUT having done that it was possible to start the car with the gear selector in any position, not that I did.
As MJ notes, it's a more complex system on the D3, but testing that, if you dare, might help pinpoint the issue.

[Mikel]

Originally Posted by HPsauce

Not necessarily, it depends what is wrong.
When my D2 S8 (OK a different, earlier and simpler model) had problems starting it was identified as a faulty F125 switch. Shorting out the relevant relay that inhibits inappropriate starting, overcame the problem.
BUT having done that it was possible to start the car with the gear selector in any position, not that I did.
As MJ notes, it's a more complex system on the D3, but testing that, if you dare, might help pinpoint the issue.

After scanning with VCDS there is no fault. Car will not start when in gear, tried on P still this same fired up straight away.

[steamship]

Remember replying to this a while ago on one of the Facebook groups.

It might possibly be the ignition switch itself being faulty. The part number is 3D0905865H, item #2 in the attached image. If you could source one from a seller that allows returns, you could try that and if the problem persists, it would eliminate that from the equation and you could return it for a refund.

Can someone confirm something about the push button start. I never used it on mine, but doesn't the key need to be in the ignition for that to work, with putting the key in unlocking the steering column?

[Mikel]

I have keyless start system. But even when I put the key to ignition still thos same just touch to right and car start