Just an update, its been all good since.... I did see that B logo come up again just the other day and came o realize that the battery was flat, enough to have lights and radio but does not even try to crank. Now what i did last time was unplug the battery which is not what you should do cause it then Super Locks the Car, I used a Hawkeye to unlock it. Hope this helps
 
Just be patient, IMHO that crossed B is not a sign of weak battery but it could be the cause of it, when that symbol is present the engine might not crank even with good battery due to the datalink failure between the BCU and IDM not other issue... let's hope i'm wrong but better be prepared with a replacement BCU and IDM within reach cos it might not start at all at a point

a.m.o.f. unplugging the battery is not supposed to superlock anything as long as the car is unlocked...eventually immobilise it
 
HAHA, Hmmm not sure im happy just waiting for it to come to be fair!

Id say you have a lot more experience in this field than me, Just that the other day it came up when I had issues with the battery and after I had jump started it went away again. So figured that there was be a link between the two...
But the good news is that Paul (Details Above) has all the Kit to fix it and is able to program everything as well, so when I do replace it it wont cost an arm and a leg.
 
What can i say...fingers crossed, though i've never seen crossed B caused by low voltage, let's hope it's the first time ;)
 
I think it happened to me once.
My little boy was playing with the electric frontseats (car was turned off). After a while I wanted to start and it wouldn't, signs of low voltage.
What do you do in such case (or any case concerning a Disco fault)? Wait a little, pray and try again. Car started but got the crossed B.
Drove home in limp mode (15min. drive). Shut her off, started again and all was well. Never had the B since...
 
offroadmad said:
sorry to jump on this thread but as immobilisers seem a common fault is there any way of removing ???
Click to expand...
if there was, no-one on here would tell you......

"Ere guv, I wanns steal a few landies - will yu tell me how to disable the alarms?"
 
Same thing is going on with my one(1999 disco 2) if i were to buy a new bcu would it need coding in or can i just whack any one in there, cheers
 
Oh noooo! I've got my own crossed B, and I'm panicking a bit as I need the car on Monday!

I know what kicked it off - I was a moron and wasn't careful enough drilling in my wheel well; caught a couple of wires from the loom right under the main fusebox (red/orange, yellow/grey, and ground). Car was fine before that - I'd literally driven it just an hour before - so I presumed not the fusebox and went straight to get my BCU to callrova, assuming I'd blown it. They refurbished it and tested it over the weekend, and it arrived back today. Plugged it back in, reconnected the battery, left it for 45 minutes, and still crossed B.
So I've now ripped out the interior fusebox, pulled the back off, and there's clearly water damage, so I'm sourcing a replacement ASAP. But if that doesn't work too, what next? Could the wires shorting have just exposed that the IDM was ready to go and pushed it over the edge, or could I have caused something else?
 

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We'll speak if the replacement IDM doesnt fix it, do as i said in post #5 and make sure that the fusebox was removed from same modell(facelift or not) facelift IDMs doesnt work well on pre-facelift vehicles nor vice-versa
 
sierrafery said:
We'll speak if the replacement IDM doesnt fix it, do as i said in post #5 and make sure that the fusebox was removed from same modell(facelift or not) facelift IDMs doesnt work well on pre-facelift vehicles nor vice-versa
Click to expand...
It's the exact same part number, I can even see it stamped on the side in the ebay listing pictures, and the seller claims tested so fingers crossed.
 
sierrafery said:
We'll speak if the replacement IDM doesnt fix it, do as i said in post #5 and make sure that the fusebox was removed from same modell(facelift or not) facelift IDMs doesnt work well on pre-facelift vehicles nor vice-versa
Click to expand...
No dice, still exactly the same problem. Six dings and crossed B in the display. I really don't understand what could be the problem now, & I'm getting a bit desperate for a solution 😬
 
Presuming that both(BCU and IDM) are faultless and they have all the power feeds and earts OK you have to check continuity on the data link between the BCU/C0661 -1 and IDM/C0587-17 SK wire... see the connector views in the electrical library. Battery must be disconnected before you unplug those connectors
 
Last edited:
sierrafery said:
Presuming that both(BCU and IDM) are faultless and they have all the power feeds and earts OK you have to check continuity on the data link between the BCU/C0661 -1 and IDM/C0587-17 SK wire... see the connector views in the electrical library. Battery must be disconnected before you unplug those connectors
Click to expand...

Tried but its too dark now. Ugh.
 
sierrafery said:
Presuming that both(BCU and IDM) are faultless and they have all the power feeds and earts OK you have to check continuity on the data link between the BCU/C0661 -1 and IDM/C0587-17 SK wire... see the connector views in the electrical library. Battery must be disconnected before you unplug those connectors
Click to expand...
There's no way for me to actually check if the BCU and IDM are actually OK, though, is there? I'm worried that plugging the BCU back in with a bad IDM (assuming that was the issue) might have fried it all over again.
 
Naf623 said:
There's no way for me to actually check if the BCU and IDM are actually OK, though, is there? I'm worried that plugging the BCU back in with a bad IDM (assuming that was the issue) might have fried it all over again.
Click to expand...
That's not a risk IMO ... i've never seen a BCU "killed" by an IDM cos then both should have been at fault... if the IDM triggers the crossed B replacing it should fix things and same for the BCU... did you check the data link and it's OK?... also what's the symptom beside the B? it doesnt crank like the OP's in this thread or what?
 
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