gorkyc

History:

1. vehicle ran when i parked it, although transmission was locked up in emergency mode.
2. few months later tried to work on it but battery was dead.
3. charged battery while still hooked into car, charger said sulfated, but pushed in a 40A charge followed by extended 2A charging and it seemed to work, battery held charge for at least a couple of days.
4. vehicle cranked fine, but wouldn't start. kept charger on it off and on for a week and it cranked fine for that whole week.
5. had AAA tow car out of my barn and move it to just outside my garage so i could work on it. Figured it was probably bad crankshaft posn. sensor that probably caused transmission emergency mode to begin with. And that that condition might also cause it not to start (although , like I said engine was starting and running when i put it away)

So now I got car next to garage. Battery is still weak, only holds charge for few days, so on its last legs. But engine wont start. Starter wont crank.

Thought about ignition switch as being a culprit, because I changed that out once before about 10 years ago. But took the steering column apart and ignition switch looked good. Bought a new one anyway and swapped it out because it could have burned a contact on the inside without leaving any exterior evidence. But still wont Crank let alone start. I am assuming car will at least crank when airbag is not connected, because i left everything disassembled when i tried to crank it.

No codes on generic OBD II reader, and none either using the VAGcom Lite interface.

before I rip out the subchassis to get to the starter, what does that inhibitor relay (J207) do? (the one under the plywood on the passengerside feet area?)

gorkyc

I bought the electronic Bentley Manual, but that is the worst manual I have ever owned. It didnt come with any instructions and it is not intuitive to navigate. basically cant find anything that explains theory of operation of any system that I am looking for. And no flow diagrams to debug anything....at least that i can find.

hillpc

J207 is the starting interlock relay, also seen it called something slightly different. The ECM pulls in that relay if the trans is in park or neutral, allowing the starter motor to crank. So if the trans position switch F125 doesn't show the ECM that it's in P or N, that's a problem. Somehow J207 is also hooked up to V94, the Central Locking/Alarm System/Interior Light Delay Control Module. It would take me some study to learn more about what it does.

There's 2 pages about the trans switch and one page about the starter wiring diagram.

I would also be suspicious of the battery, since low voltage (11.5 volts - hearsay only; I can't point you to a reliable source on this right now) can prevent a bunch of ECM things from happening. Do you have at least 11.5 volts while cranking? Put a big battery charger/jumper on it while cranking?

gorkyc

Thank you for info. I haven't had time to work on it again yet, but need to make sure signal from ignition switch is making it to the j207 relay. It didn't crank in P or N but I haven't measured the ECM signal at J207 yet. Wouldn't a F125 failure throw off a code though?

It's probably not low voltage because I have one of those big shop chargers that can supply 200A cranking and I usually had that connected when I tried cranking. And it was cranking with and without that charger connected when it was in my barn.

I hope to get some time to work on it tomorrow. Priority today is to figure out what is wrong with the well. Woke up to no water this morning.... Challenges of living on a farm. )

gorkyc

I looked at the Bentley manual again, and I did find the right wiring diagrams, but I still don't think it's a very good manual, and I prefer old fashion paper manuals any day.

Anyway, don't seem to find that ECM signal. Working back from the starter, looks like the enable signal comes pin 17 on J207 which gets connected to pin 19 when central locking/alarm/interior light module(V94) connector C pin 16 is at the opposite voltage of J207 pin 19. J207 pin 19 looks like it is connected to pin 50b on the ignition switch. Looks like ignition switch pin 50b is open until the ignition switch is activated at which time it gets connected to 12VDC.

So when ignition switch is in the start position, 12VDC comes out pin 50b and goes to pin 19 of J207 relay. And if the signal from pin 16 of connector C of V94 is GND, the J207 is engaged which connects 12VDC to the starter relay.

So the V94 signal must be the ECM signal you are taking about, but I don't see any explanation anywhere about the logic behind that signal.

I've got 12VDC coming out of pin 50b of the ignition switch. But the signal from V94 seems to be high impedance, not GND or 12VDC.

tozoM8

Park neutral safety switch could be bad dirty.

gorkyc

the thing is i know the lock solenoid is actually working because without ingnition on, and foot on brake it wont shift out of park. when you apply the brake, you can hear the clack and the shifter is allowed to move.

i might have early firmware on my D2 because when i put it in neutral i can't turn the ignition off or take out the key, and from neutral it will allow me to shift into any other gear without putting on the brake.

when you say park neutral safety switch are you referring to F125 down under the car on the driver side of the transmission, or the Tiptronic Switch -F189 in the shifter mechanism?

the bentley electronic manual is definitely not easy to use

hillpc

Well, I do like the wiring diagrams better than the giant pages of hundreds of crossing lines I'm used to from American car service manuals. But I miss the description and operation sections that are in GM and Ford manuals, which explain how the stuff is supposed to work before getting into details of troubleshooting and repairs. I buy a service manual for every car I buy, new or used, and read it to find out about the car. I bought one for my wife's 2008 Mazda MX-5 Miata, and found not a peep anywhere in there about description and operation. I had been looking forward to learning about the variable cam timing. Nothing at all beyond "remove screw A, remove part B, replace Part B, replace screw A. I wonder if all the description and operation info is in some other book or manual, or in a training course for factory mechanics.

I understand there's Audi information available at erwin.audi.com; when I briefly went on their website I got the impression it's a subscription service of some sort. They do seem to have training information and description and operation-type stuff as well as repair info and troubleshooting info. Many of the products I saw were in German, though.

update - found a USA page https://erwin.audiusa.com/erwin/showHome.do