OBD2 stopped working

[remarklima]

Hi all,

Any ideas on why my ODB2 port appears to have stopped working?

I had a ODB2 bluetooth reader in there and it was all OK, but appears to have stopped working, even with another ODB2 Bluetooth dongle.

The other has a power light, which does show up so there's power, just not a signal? Any thoughts on where to start? Everything else is working fine!

Thanks

 

[remarklima]

One more thought - I've added a DSC controller and 3 axis accelerometer, hence I have disconnected the ECU and battery, and reconnected it all back up with the accelerometer spliced into the CAN bus wiring.

I could disconnect the DSC box easily? And I could unplug the accelerometer with a bit more effort if they're routes to explore?

 

[deMort]

I assume the can bus splice is what's supposed to be done and it is correct ?

If so then there's nothing i can think of .. from memory its a single wire from the gateway that supplies the info to the port .

I would start by having a dedicated tester on the system to prove there is no output at the OBD port .

 

[remarklima]

Thanks as always deMort!

Yes, the splice is working, I can see the values in the DSC sport software changing and the accelerometer returning a value.

Obviously, there a lot of messing around with wires under the glovebox and the rear - I did unplug the ECU / DME to do the splice to make sure nothing was going to be disturbed by a soldering iron, but maybe I'll get back in there and check.

I'll need to check power as well at the ODB2 as well, so out comes the multimeter again!

 

[remarklima]

Hi,

So there's power to the port, however my multimeter doesn't have small enough probes to get into the ports.

First question, is there a way to get to the back of the OBD2 port without removing the glove box? Or a way to unclip and drop it down?

Secondly, where's the other end of the signal wire? I can do a continuity test, as I had the ECU out again to check everything was OK and it's 100%...

The splices are all good, and if there was something up with the CANBUS wiring I'd assume the whole car would go mental - which it doesn't, it runs spot on, just no OBD2 signal :/

 

[remarklima]

OK, so I've managed to pull out the OBD2 socket (I didn't need that skin on my hands after all!).

And tested all the pins... I used the earth in the footwell 12v socket (cigar lighter) so to make sure everything is to a known earth.

This is with the engine off and connected to a C-TEK trickle charger

Row 1:

1 = 12v
2 = empty
3 = 8.8v
4 = Earth - good continuity
5 = Earth - good continuity
6 = 2.5v
7 = 11.3v
8 = empty

Row 2:

9, 10, 11, 12 and 13 = empty
14 = 2.5v
15 = empty
16 = 12v

So, to me that looks good, all wires are correctly presented and providing signal and earth...

Things I've changed:

Head Unit - the ODB2 was 100% working as it came with a bluetooth adaptor and the head unit could read the codes etc...

Removed Nav and CD unit with optical bypass loop. Would this cause an issue? Maybe it worked as did this at the same time as the head unit.

DSC controller and 3 axis accelerometer - the latter is the only thing I can think? I couldn't get it installed up front as the wiring was too tight, but have since had the centre console out and checked the wiring. I had to install the accelerometer to the ECU CAN BUS wires in the rear deck but had everything disconnected and the car runs fine.

Would the nav and CD changer unit affect anything!?

 

[deMort]

Basically your wiring tests seem to be in the ballpark of what i would expect .. you have the feeds and earths required ..

The 2.5 volt ones are can bus .. this would be a switching current but you would need an oscilloscope to actually see this as being correct ... its about correct for a meter though.

If you had connected something wrong or faulty to a can bus wire then you would have a load of codes .. which atm you cant see ! and systems not working so that's unlikely .

Soo .. if the plug and wiring is ok we are left with your tester .. you need to connect another device to see if that works ..

If not then things like the K lead .. maybe an issue there .. i don't know what sort of signal you would get on that wire .

Your issue is of course you need a tester to communicate to a vehicle to be able to check or alter anything .

At a push and if it was me .. i would swop out the gateway CU and then see if i could communicate but we are into getting a garage to look at it there .

As with anything that stops working after work has been done .. you recheck or remove the items to see if it makes a difference .

In short though .. nothing stands out to me as being wrong .

 

[remarklima]

Thanks as always! Yes, the wiring looks fine, and has signals so a good start!

Is the gateway in the frunk, on the left hand side? I've read about it but wasn't sure if it was related?

I'll dig out the nav unit and plug it in... I did try with the accelerometer and DSC module disconnected and it was the same... I've also tried with the neighbours odb2 reader, just a generic thing... It powers up, but again no signal.

I'll try the gateway, otherwise I will have to see what a specialist can find with the right kit, but at least I can say the wiring and voltage looks good.

 

[deMort]

Gateway CU is under a plastic panel and under the wiper linkage o/s/f , X3 phillips screws to remove the panel but you will need a donner gateway to fit ...

This is just a guess from me atm .

This is certainly not a normal gateway issue and these are pretty bulletproof .

 

[remarklima]

Thanks as always for your help, time and patience!

Final question, would a new gateway need to be coded to the car? Or can I just plug and pray?

 

[remarklima]

Double post

 

[deMort]

A gateway would certainly need coding to the car , it would probably need a vehicle handover as well to wake it up if a new item .. done with a tester .

Please be aware .. i'm not saying it's a gateway fault .. i'm merely saying i would swop it out with spares we have at work to prove or discount this as being the cause before moving on .

Garages like mine have these as substitute items for diagnosis .


In this instance i would have to code it from another vehicle then fit to yours to see if the tester could then communicate .

 

[remarklima]

Hi DeMort - the saga continues.

There's a local specialist who I'll try and see what's happening, but I wondered if I'd broken a wire when changing the Head Unit.

So today, got to the gateway unit, and tested continuity between Black / Red and Yellow / Red - the CAN hi and CAN lo from the gateway to the OBD2 port... Thinking a break would mean it'll be a way to track down the broken wire by colour.

However both had continuity

I assume the OBD2 diagnostics run off the CAN network, and not the K-Line ones? As not sure where they go, or if they're relevant?

 

[remarklima]

OK - turns out all along I've been a complete numpty!

Thank you again DeMort for the patience and help, as always I really appreciate it!!

After all that, my OBD2 bluetooth dongle was duff - this is despite my neighbour's two different generic readers also not working.

So, turns out everything was OK... Oops!

Anyway, in reading through I've learnt a bit, so;

9x7.1 uses the K-Line for diagnostics, which runs directly from the DME and not the gateway. It does have the diag CANBUS but I assume this is for PIWIS and coding modules.

The protocol is ISO9141-2.

The 9x7.2 does use the CAN BUS for diagnostics.

Also, there appears to be 4 CAN networks, Drive, Display, Comfort (or Komfort!) and Diagnostics. The instrument cluster and the Sport Chrono have the Display CAN.

There's some interesting projects with Raspberry Pi's or arduino's that tap into the Drive CAN - but thinking or checking out the display CAN.

Thanks again DeMort, all good for now

 

[deMort]

I'm So Sorry young man .. i've been offline for a few weeks now and this post dropped off my radar .. i'm also trying to catch up on rather a lot of posts atm.

K line .. that's DME communication .. i expect the rest of the control units will communicate with the tester via can bus from the gateway .

I can talk to the control units on the comfort can only with a tester when ignition is not switched on ( a dead system ) but i cant talk to drive can components such as DME , Tip or PSM .

I suspect K line is more for a " broken " can system .. not sure there .

As with all testing .. if replacing something then you use a known good item .. hence a tester you know works on another vehicle .. that is a 100 % check .

I will add .. i learnt this the hard way over the years .. i've fitted brand new components that havent fixed an issue .. i've then gone around the houses trying to figure it out ..

The new item was defective !!!

Hence these days .. if unsure i swop with a known good item .. life sucks at times with cars i can tell you .

Once again .. sorry for not replying sooner and well done for figuring it out .. it wasn't easy as you had already replaced the dongle !!!


EDIT .. btw .. if you come across a laptop or device that can connect to a can bus and list what signals are there then let me know please .

On a training course many years ago they had a laptop that could do this .. turns out they thought Porsche techs could break a car with it so it wasn't issued to the garages .. i've been after one ever since .