D2 CAN system

I have seen a failed BCU on a V8 cause a multitude of problems.

They aren't that hard to change and shouldn't be very expensive.

The BCU controls a lot of the dash as well, but it shouldn't cause they 1842 and 1843 faults, they are saved in the TCU and read directly back out by the Nanocom.

Can level monitoring is something directly handled between the engine ECU and the TCU.

The position switch fault will be an issue between the TCU and the XYZ switch. Either wiring or switch.

All of this is correct, UNLESS you have a wiring issue or earthing issue or water ingression problem, if that's the case, all bets are off!

Check the earthing points near the battery, I've had an issue with them before.

I'll see if anything else comes to mind.

Going out now to check the BCU for water. I will also take my oscilloscope, why didn't I think of that before, to check CPS etc.

Thanks for looking.

BCU clean and dry. Same for the Wabco next to it. Few more tries and then I think I'll resurrect the D1. No bloody computer in that.

Still, there's a silver lining. It's no longer overheating...[bigsad]

Without any pretensions at being an expert, (as I am just a legend in my own mind and an opinionated git, so still beneath an expert), I am of the righteous not humble opinion that you should disconnect the loom that runs from xyz (I always prefer neutral safety switch but trying to modernize here) across top of transmission to cdl and other sensor switches then up to the tcu wiring loom, it's been a while but I think there is a bung where it runs into the body that needs pushing out, a few inches of loom in the console that you get to by removing the window switch panel and then a connector to unplug and you remove it back out from underneath the vehicle.

Unravel the whole lot and check all the wires, very carefully as easy to miss a bit of insulation chafed off, then rewrap the heat foil and wrap the loom with plenty of electrical tape. It needs to be fixed to stand off from the top of the transmission using clips which may or worse may not be there (they are fixed in place by transfer case to trans top bolts) so that it doesn't rest and rub on the transmission.

I did this while I had console out which made it easier to unplug the connectors on the driver side of the trans.

This solved my irregular tcu codes and out of the blue 3rd gear limp mode, mostly (but sometimes dry weather) when it was raining and puddles splashing up under car.

I've got pics of this somewhere in the what happened to your d2 thread ( i think)

I'm very much inclined to think you have a wiring problem not any actual electronics module issue. But as above I'm not an expert, just making a suggestion.

Yes, John. That's my plan for tomorrow, although I hate getting under the car nowadays. I recall the loom can rub through on a P clip or something. It's just weird that it all comes at once, but then it's happened before with water in the fusebox, so I shouldn't be surprised.

I spent most of today cleaning and inspecting the various control units and their wiring. Found some issues, but nothing changed when I fixed them. I thought I'd found something when the grey plug that connects the ECU to the High low switch, and others, was full of oil. Hadn't heard of that one before.

Attachment 195039

And yeah, I grew up calling it an inhibitor switch...

I though XYZ was a specific LR term, is it modern, generic parlance?

Quote:

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Originally Posted by Tins

Yes, John. That's my plan for tomorrow, although I hate getting under the car nowadays. I recall the loom can rub through on a P clip or something. It's just weird that it all comes at once, but then it's happened before with water in the fusebox, so I shouldn't be surprised.

I spent most of today cleaning and inspecting the various control units and their wiring. Found some issues, but nothing changed when I fixed them. I thought I'd found something when the grey plug that connects the ECU to the High low switch, and others, was full of oil. Hadn't heard of that one before.

Attachment 195039

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I remember reading this way back when..... may be of some help

ZF 4HP22 problems and valve block rebuild link

Quote:

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Originally Posted by thai_tiger

I remember reading this way back when..... may be of some help

ZF 4HP22 problems and valve block rebuild link

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Thank you, ไทยไทเกอร์

Last time I tried it I nearly had a stroke. The Nano lit up with maybe 8 faults. Sheesh. Seems like it helps to reconnect the Red plug. But the P faults and M&S were still there which makes me think that maybe it is the wiring for the trans. Anyway, enough for today.