2013 Audi A7 doesn't crank/start.

[hangtenboy]

Patience , I'm on a different time zone, looking into it now.

LE: how do I have to read the excel? Columns A and D indicates where the test light has lit? And which one were checked against minus and which one against plus? Because 1, 2 and 4 are minus and there is N indicated, which I would read that it did not turn the test lamp ON, against battery plus. Is this the way to read it?

All were checked with test light connected to ground, so just checking for power in pins, but no ground checked in this test. I did however test 1,2 and 4 on t92 previously for good ground and they were all fine.. So to answer your question, all were checked for +; 1,2 & 4 for -

 

[TTT]

Right. My feedback.

T94/3,5,6 are ecm relay switched plus
T94/1,2,4 are minus
T94/87 is ignition switch plus
T94/64 permanent plus

Which seems in line with your findings. So ecm has good power and grounds.

Next up, to verify communications. Canbus according my notes, its on plug T32, terminals 3 can low and 4 can high. Fire up the oscilloscope, just use one channel to scope each wire at a time. Set the total voltage scale to something like +/- 10V; DC coupling, probe 1x, no trigger, timescale 500 us (play with longer or shorter). Vertical resolution of this scope is bad, but it is what it is. Probe minus cable ideally needs to be on the battery minus, even if that is in the trunk. Do not use a battery charger, if this scope is AC supplied.

Make some pictures of what you see on scope and post here. Maybe a movie or two, up to you. You are looking to have something like this, this one has two channels connected at the same time. If testing is done with plug disconnected, the waveform might be a bit distorted at the rising and falling edges, due to missing 120 ohms end resistor, which lives in the ecm.

 

[hangtenboy]

Right. My feedback.

T94/3,5,6 are ecm relay switched plus
T94/1,2,4 are minus
T94/87 is ignition switch plus
T94/64 permanent plus

Which seems in line with your findings. So ecm has good power and grounds.

Next up, to verify communications. Canbus according my notes, its on plug T32, terminals 3 can low and 4 can high. Fire up the oscilloscope, just use one channel to scope each wire at a time. Set the total voltage scale to something like +/- 10V; DC coupling, probe 1x, no trigger, timescale 500 us (play with longer or shorter). Vertical resolution of this scope is bad, but it is what it is. Probe minus cable ideally needs to be on the battery minus, even if that is in the trunk. Do not use a battery charger, if this scope is AC supplied.

Make some pictures of what you see on scope and post here. Maybe a movie or two, up to you. You are looking to have something like this, this one has two channels connected at the same time. If testing is done with plug disconnected, the waveform might be a bit distorted at the rising and falling edges, due to missing 120 ohms end resistor, which lives in the ecm.

Awesome. I will do this in an hour. Thanks for the detailed instruction

 

[TTT]

Take your time. It’s 20:23 here anyway.

 

[hangtenboy]

Oh, I don’t expect speedy reply from you. I’m just excited to get some more testing done

 

[TTT]

forgot to say, during testing, ignition must be on. Maybe you knew already, just making sure.

 

[hangtenboy]

The plug on the gateway module is a T32. Hopefully this was the component I was supposed to connect to? I followed your instructions, and I see activity which I'll post but I thought that the Can High and Can low were opposite each other, unless I am reading wiring diagram incorrectly? I followed wires from ECU to Data Bus On Board Diagnostic Interface -J533- and it looks like the pins are 5 for Can Low and 21 for High, so I am just checking that I'm at the right pins before I post results in case this isn't what you meant

https://imgur.com/a/cu5e5sI

 

[TTT]

Yep. I got it wrong, I was looking to module 17 instead. Engine is T94 terminals 67, 68, which indeed come to the gateway you indicated. However, since there are some junctions in between, please do the measurements at the engine 1st. Maybe at the gateway terminals 5 and 21 later.

 

[hangtenboy]

Yes, sir. Last night I did decide to do measurements at the 67 & 68. Nothing registering essentially. Each pin had approx .2 v directly at ECU when back-probing the pins with ignition on and ECU connected and the waveform wasn't even close to being right.

https://imgur.com/a/NzODNpU

https://imgur.com/a/0YifNAd

 

[TTT]

Well, that is bit unexpected, from several reasons. One, I did not know you had a picoscope in the meantime. Since we established that ecm is alive and kicking, I would of expect at least 2.5V idle state for canbus. Can you please do same measurement at the gateway pins 5 and 21, ignition on and as well, please increase the scope time base from 500 us, to something higher.

 

[hangtenboy]

Brand new user of Picoscope but I bought it 2 days ago. I will check on gateway pins and post here in a few hours. I know it’s getting late there already

 

[hangtenboy]

https://imgur.com/a/HO3rXLa

I was able to collect data from Pins 5 and 21 at the Gateway module. Not sure if the spikes are caused by me but does the waveform look ok? I was thinking yes, but I'll wait for your determination. This does look like gateway is talking to something or something is talking to gateway, right? I am going to try and see what else is on those wires in my wiring diagrams, if only to learn some more. Also, if the taking pics with ym phone camera sucks and you want higher resolution from Surface, just let me know and I'll stop sending them that way

https://imgur.com/a/W7nV3e4

 

[TTT]

Spikes are normal and predicted by the makers of canbus, in the 70s and 80s. As canbus is differential signal, tranceiver chips will do CAN high - CAN low and all noise will dissapear.
Signal looks ok to me, and there is much more to say about it, but not now.

If (big if) the testing and connectivity of probes were ok in both sides testing, do you agree that can high and can low wiring seem not connected between gateway and ecm? In your scans, gearbox seem to talk, which means wiring between gateway and junction TV33/TV37 are ok. You need to go back to ecm and maybe try front probing with thin probe, and test again to be sure there is no data packages reaching there. With same 1ms per division, but so far, wiring seem to be broken between wiring junction E93/E94 and ecm.

 

[hangtenboy]

I agree. I have am retesting again at pins 67,68 on ECU, just to be 100% sure that there is no activity on them and so I know I am making good contact. I have very small pin probe that slides all the way into back of connector to make contact with metal on pin

 

[hangtenboy]

I reverified that there is no recognizable voltage coming thru to pin 67,68 on ECU. Tracing back to next component between ECU and gateway which is T17a (Left Plenum Chamber E-Box Connector Station, White). Currently trying to locate that. Would the Left Plenum Chamber be the left (driver side) as looking from driver's seat?

 

[Uwe]

Would the Left Plenum Chamber be the left (driver side) as looking from driver's seat?

Yes, left and right are specified from the perspective of someone sitting in the car facing forward.

-Uwe-

 

[TTT]

Up to and including T17a is fine, like I said, gearbox is beyond that point, and gearbox is talking. Concern point is E93 and E94 junctions, but they don't say where that is.

 

[hangtenboy]

Up to and including T17a is fine, like I said, gearbox is beyond that point, and gearbox is talking. Concern point is E93 and E94 junctions, but they don't say where that is.

Great! I will find them. By gearbox, does that mean the TCU? This, right? Address 02: Auto Trans (J217)

 

[TTT]

J217 is the TCU indeed.

 

[hangtenboy]

J217 is the TCU indeed.

Also, I'm sorry I missed that piece about E93 and E94. I'll keep my focus there since you have already said that appears to be where I need to be looking.