D2 CAN system

**Tins** · 24th November 2025, 03:02 PM

Nothing like having a spare.

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**shack** · 24th November 2025, 03:51 PM

Originally Posted by Tins

Nothing like having a spare.

IMG_6698.jpg

Looks pretty normal to me!

**Adarewyr** · 24th November 2025, 03:59 PM

Originally Posted by Tins

Nothing like having a spare.

IMG_6698.jpg

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Hey, I can play that same game! Just don't have quite as wide of a bullbar to sit on

**Tins** · 25th November 2025, 10:36 AM

Ok. I haven’t done this before and I don’t know if I am going to, but if I wind up swapping out the ECU is the security code transferred from the BCU? IOW, the code is stored on the BCU permanently? If I do the swap things like the EKA will remain the same?
I have the transmission harness out at the moment being cleaned so I can inspect it. After that I don’t know where else to go

**Tins** · 25th November 2025, 10:38 AM

Oh, did I mention that I hate buses? They only have one good seat and they don’t let me sit in it anymore.

**thai_tiger** · 25th November 2025, 01:16 PM

Attachment 195039[/QUOTE]

Check to see if oil got into the TCU as it did in one of mine, which gave some weird symptoms

**Tins** · 25th November 2025, 01:45 PM

Thanks, tt. I haven't found any oil inside the plugs and harness for the trans at all, but I did find a plug that had been sitting on the exhaust. Not sure yet what it was for. Other than that, and the 25 years of grime, I can't see anything wrong with it, but I'm glad I pulled it out because the insulation was nearly worn through.
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I'll find what this is meant to be connected to and use deutsch plugs.

**BradC** · 26th November 2025, 12:42 AM

Looks a bit like the wicked witch of the west got caught in the rain.

**sierrafery** · 26th November 2025, 12:50 AM

Hi, first of all the CAN on a D2 is exclusively between the engine ECU(ECM) and TCU nothing to do with others(BCU, IDM, transmission harness, etc), it's a two wire link from ECM red plug pins 32 - 35 to TCU 16 - 44(yellow - white wires) and it goes through C0162/0448 pins 5 - 6(grey square connector near the ECM, it can be dirt or bad contact there too)... so for the CAN fault codes in your first post the problem can be only on that particular circuit or with one of those ECUs, those codes are common if there is oil in the red plug and it gets to the involved terminals.

as about the BCU's security code, the ECM must be forced to learn it with nanocom in "Utility - learn security code" if either the ECM or BCU are replaced otherwise it's immobilised, that's all

**Tins** · 26th November 2025, 08:38 AM

Originally Posted by sierrafery

Hi, first of all the CAN on a D2 is exclusively between the engine ECU(ECM) and TCU nothing to do with others(BCU, IDM, transmission harness, etc), it's a two wire link from ECM red plug pins 32 - 35 to TCU 16 - 44(yellow - white wires) and it goes through C0162/0448 pins 5 - 6(grey square connector near the ECM, it can be dirt or bad contact there too)... so for the CAN fault codes in your first post the problem can be only on that particular circuit or with one of those ECUs, those codes are common if there is oil in the red plug and it gets to the involved terminals.

The yellow an white twisted pair were damaged a little. I replaced them with the same wires from a spare red plug I have. I guess I'll check if I got them mixed up, but I don't think so.

C0162/0448 was full of oil. Cleaned it. I think my issue is that I went down too many rabbit holes at once. So I have been taking my time, repaired the loom over the TC, which was needed, repaired wiring from the red plug. I may have messed that up, but I'm usually good with wiring. So I'll go over it carefully today. I just wish I had the wiring diagram out there with me, and not in here on the screen. *

Until this week I wasn't aware that oil would creep up to C0162/0448. Red plug, sure, and I keep it clean. Now I know....
IMG_6694.jpg

Thank you, sf. I was hoping you'd chime in. The knowledge that the CAN is only between ECU/TCU is helpful. I knew the D2 a true CAN system, but this narrows it down more.

I'll only change the ECU when everything else is AOK, and I do have a Nanocom.

* No, I don't have a printer, or an iPad, and the phone screen is too small for my 72 yo old eyes

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