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Disco 2 (td5, manual) B-slash error


bofhdk
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Hi all,

 

Firstly, let me apoligize if this has been covered elswhere, but I don't really know what to search for.

Aaaaanyway, after fiddling with the electrics on my LHD D2 td5 (`99) the car won't respond any more, and I get the attached display in the dash.

There are no other issues (as far as I can tell) and I have no clue as to how to proceed.

The fiddling was me trying to figure out why my LH headlamp dipped beam wasn't working, so I extracted the under-dash fusebox and started measuring things. After reassembling everything, the headlamps worked fine, but the ECU/BCU (or somesuch) had decided to become unresponsive. Central locking, key-fob etc. are all dead, and when turning the key to pos2 I get 6 "bings" and the odd B-with-a-slash in the display.

 

So now I have a 2 tonne lump sitting in the carport :-(

 

d2_dash_error_anim.gif

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Hi. That symbol means communication failure between the IDM(interior fusebox) and BCU, can be any of them but as you fiddled with the IDM the problem is probably there, especially if you didnt disconnect the battery before you unplugged it... better try with a known good one, it has o be off from same modell(facelift or not), battery diconnected and after the swap and battery reconnection ignition on 2 left for 5 minutes to regain digital data comms with the BCU....  that's all

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On 2/4/2020 at 8:51 PM, bofhdk said:

...more info when available ...

So, after a rather chilly few hours checking all the black wires to the IDM/Fuses, BCU and ECU (all had a nice ground) and swapping all 3 units (from a similar vehicle) I'm still stuck with the flashing B-with-a-slash.

I fear this is where I have to toss in the towel and hope to find someone knowledgable to help out as this is akin to rocket science for me.

Thanks for the suggestions though :)

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The ECU has nothing to do wih this so don't waste time with that... all you have to check now is continuity on the data link wire between the IDM and BCU, It's a grey/pink wire between C0661-1 and C0587-17,  disconnect battery, unplug hese two connectors and check wih multimeter across those pins... see Electrical library - connector views and concentrate to identify the correct pins...if you dont have it here it is https://www.sugarsync.com/pf/D8700125_05791262_69063?directDownload=true and if there is continutiy try to swap the engine bay fusebox too.

btw...did you check carefully to not be any corrosion in IDM or BCU plugs?

Edited by sierrafery
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7 hours ago, sierrafery said:

The ECU has nothing to do wih this so don't waste time with that... all you have to check now is continuity on the data link wire between the IDM and BCU, It's a grey/pink wire between C0661-1 and C0587-17,  disconnect battery, unplug hese two connectors and check wih multimeter across those pins... see Electrical library - connector views and concentrate to identify the correct pins...if you dont have it here it is https://www.sugarsync.com/pf/D8700125_05791262_69063?directDownload=true and if there is continutiy try to swap the engine bay fusebox too.

btw...did you check carefully to not be any corrosion in IDM or BCU plugs?

Cheers!

So, loads of continuity on that wire.

No visible corrosion on any contacts in IDM & BCU - plugs & sockets seem fine.

I'm unfortunately unable to procure an engine bay fusebox as the owner of the parts disco is on holiday for the next week or so.

I'm wondering how the engine bay fusebox comes into this as I've only been mucking about under the dash?
(or does the eng.bay fusebox also have some built-in "smarts" like the IDM/fusebox?)

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In all the cases i've seen that crossed B was caused by the IDM or BCU failure and one case when the data link was interrupted. It's the first time i see when all these 3 elements were ruled out without result so my presumption is that maybe a feed into the IDM from the engine bay fusebox is the problem... at this point i have no other ideea(provided the units you swapped are 100% in working order)

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Ahh - ok. Now I understand (a little bit at least) :)

Unfortunately I have no way of verifying whether or not any of the units are OK.

That, coupled with the fact that I really don't have a clue about this sort of thing makes me think that I'm welkl & truly buggered and now need to get shot of a 2T paperweight sitting in my carport.

To quote a certain comic strip protagonist: Augghhh!!

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Btw, when you checked continuity on the wire beween the units didnt you by any chance check against earth too? it would be good to rule out a short to ground on that link as well. As i said i've seen thys symptom many times and it was always cured by replacement BCU or IDM in about a 60 - 40% occurance for the units

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Woohoo! - The "tractor" is running again! 😄

I had apparently not been diligent enough while checking fuses. Fuse F13 in the engine bay was blown.

This fuse supplies the BCU with +12V, whithout which the BCU goes on strike and drags the ECU & IDM with it it seems.

I blame the damp, cold darkness of my carport for the oversight.

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Well - I did check the fuses, but somehow I missed that one (probably due to the less than optimal conditions (dark, rain, cold)) and also that the break in the fuse was small & down to the side of the fusible material.

I'm still kicking myself over it and have made a mental vow to never again think that a fuse is ok without conducting a continuity check in addition to the visual.

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