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2003 V35 Coupe - please show me your OBD wiring!

Adam P
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Adam P Rookie

Adam P

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Hi all, long time lurker, first time poster. I've used this forum many times for information and its been a godsend, thank you to all the contributors I've relied on over the years.

Now its my time to ask for some help directly.

In short if you have a V35 couple from 03 or thereabouts, can you please take a look at the back of your OBD port and tell/show me the pin/wiring assignment?

 

Background:

I'm trying to read the ECU to confirm mine is compatabile with uprev, however no matter what I've connected to the port nothing works. My latest attempts have been trying to use Nissan Datascan II https://www.nisscan.com/NDSII/index.php with 2 different cables. The second attempt was with the bluetooth connector, however I noticed that the connector did not power up at all and I couldn't get bluetooth to even pair with my phone. I put the dongle into another car (a toyota) and while it could not read the ECU (of course) it did power up and pair to my phone.

This made me wonder if the OBD port is even wired, so I took a look.  It is connected, however the wiring does not follow any reasonable OBD spec according to any google search. Here is an example:

https://en.wikipedia.org/wiki/On-board_diagnostics#OBD-II_diagnostic_connector

My OBD connector is attached to the post. You can see for example that power is on pin 3 (and it is live I've checked). Power is normally on pin 16 at least on all the standards I've looked at.

So what I'd like to find out is this normal? Hopefully its not, and I can rewire it back to normal, but to do that I'd like to see what is going on your car.

If anyone out there has an 03 v35 or has seen this before and knows what is going on, please help... this is putting a terrible spanner into my project!

I'd also like to suggest a sticky thread related to v35 OBD go up or maybe added to the FAQ, I've seen similar issues come up in here quite often without a clear answer as to what is going on with the v35 OBD port.

Thanks everyone, I appreciate your input you'll definately be on my xmas list if this can be figured out.

DSC_0540.JPG

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The Max Mentor

The Max

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Question for you. Did you switch ignition on to see if it powered up then? I would have to check my vehicle later on as well but I have a theory about Nissan having wired it up in a possibly unconventional way and rely on power from the ignition circuit rather than direct to the battery on pin 16, for whatever reason.

Adam P Rookie

Adam P

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I did power up the car to check that, no dice. I am planning to put power back on 16 but I'd like to see what everyone has first... however I believe the dongles I've used are looking for power only on 16.

 

Edited by Adam P
Adam P Rookie

Adam P

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interesting, thanks sonicii. Have you used OBD2 software to talk to your car's ecu?

your peach coloured pin 14 (CAN-L) and my red coloured pin 3 (vendor assigned) are the only differences. Probably stretching it but if you have a volt meter can you see what you get out of ping 16? (the red/white wire, I only get about 3v out of it which doesn't sound like enough)

I can't get into the car to check again (healing from surgery) but its killing me to find out what is going on here.

Adam P Rookie

Adam P

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For anyone following this a shop with experience on v35's has told me to move my red wire to the location of the pink wire in the second photo; move pin 3 to pin 14 - the exact difference in wiring between the 03 and 05.

I'll update this thread when I get to test this out (going to be a while, but I can't wait to see if it works!)

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sonicii Veteran

sonicii

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Posted

I have a OBD2 reader I use with NissanDatascanII and it works fine, I also have a consult2 clone which works fine.

Let me know if you still need me to measure the voltage on pin16

  • 9 months later...
Adam P Rookie

Adam P

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Guys time to reboot this thread Ive been away from it for a while but the problem is still outstanding - I cant talk to the ECU with anything.

This has lead me to looking at the CAN circuit checks as per the FSM for 03 G35. Now this is has really blown me away because I run into frequent differences between what the FSM says I should see and what the car actually has, especialy when I go through the SMJ connectors they are always not pinned in the blocks I should be seeing stuff.

Avoiding those checks - wtf - I went to the CAN comm circuit check as that should its pretty simple. Disconnect ECM, TCM and connector F102 and check continuity between the ECU connector pins 94 and 86 (continuity should not exist).

Of course, continuity doesn't exist, because it can't; pin 86 isn't even wired in the connector.

Pin 86 by the way is CAN-L so I'm struggling to how this is so.

Can someone with a v35 please take a look at their pin 86 in the ecu connector and let me know if you have it?

I'm really starting to think my car is wired different :( I've got no idea how or why or if I'm just a dingus who should put down the tools.

Attached is references, thanks.

 

lan-52.png

ecu.png

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sonicii Veteran

sonicii

Posted
Posted

Probably can't help right now, but can only suggest you keep in mind you have a V35, not a G35, there are differences!  USDM vehicles sold after 1996 were required to be fully OBD2 compliant, Japan has no such requirement, one of the reasons many generic OBD2 readers don't work on V35s.

That said, I wouldn't expect the wiring to be all that different.

  • 3 weeks later...
Adam P Rookie

Adam P

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Quick update.

Traced the engine harness to confirm everything connects back to right places on the ecu. It does, with a couple of not so important exceptions. 

Traced the CAN H/L lines across to the obd plug. Found a short, thought eureka, fixed it, but no, thats not my problem.

I'm trying to connect to the ecu via k-line (pin 7 in your obd connector using nissan datascan), so it meant nothing and I still couldn't get it to talk. Infuriating!

Broke out the soldering iron, made a complete bench harness for the ecu. Plugged it into my pc with the ecu and obd cable, and it worked. Put my lap top on to check it that way and it didn't go.

wtf. 

This was the 4th computer I tried, and 3 different cables, but finally a break through. The bloody laptops were pretending to talk to the cables but weren't. Couldn't believe it!

However when I took it back to the car with the pc, it didn't go.

wtf, again.

Researching the k-line network, its a star topology, typically every module is wired to a single point. If the voltage is off, chances are one of the modules connected has a short. The multimeter said it was a little low... but the FSM for it is a little vague on what it really should be.

Testing this I found that if I disconnected every module I could reach except the ecu, I could talk to the ecu with my pc. Getting somewhere...

With more testing I found that if either the body control module or the AT control module are attached, no dice. So either they are both shorted or there is just something wrong with the way they are set up out of the factory.

There is a shit nest of aftermarket japanese radio / highway card wiring in the way, its tapped into fuses and shite... thats coming out next to see if this is causing it. I found a blown fuse behind one of the taps, maybe it is.

But at least I've been able to confirm the ecu will take uprev as I could see the serial number in the ROM. I also know a lot more about the wiring in a V35 than I really care to.

Only took 10 months of stuffing around to get this far. Should be easy from here.

LOL.

 

 

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Adam P Rookie

Adam P

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Toll card reader wiring removed, and now the body control module also works on the k-line network.

Just the AT control module to go. Problems with this circuit are less obvious, but I figure, worst case, I could just cut the k-line out for this module, maybe hook the ends of that wire up with connectors so I can reattach it to keep troubleshooting. That would mean no diagnostics for the auto... but it wasn't working before either so no loss. 

Does anyone know if the assumption that k-line is only used for diagnostics, and the CAN bus for inter-module communications is correct 100% of the time? Given the k-line network has been inoperable the entire time I've owned the car (5-6 years) it would seem to be so. But it would be nice to be sure about something for once before diving in.

 

  • 2 years later...

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