BCU Repair or Replace?

Naki kouyioumtzis · Jan 12, 2020

Thanks again to this great forum for tips and help.
I had the Flashing B Display, the CL and indicators both give up on me all of a sudden, on my 2000 TD5 auto.
I removed the BCU and reflowed the soldering on the main pin/ joins, and it seems to have done the trick, so far? I will give it a test run to make sure. hopefully it’s not just a temporary fix.
The engine runs/ immobiliser is activating etc. So hopefully I haven’t done any damage?

The only one slight niggle, is the mileage display is now flashing for some reason? I guess I can live with that, although it’s slightly iterating. Does it mean something that it’s flashing?
Ps I do not have the Nanoncom yet, though I guess I probably should buy one! I wasn’t sure how long I would run the Disco for when I first bought it, so I held off. But I think it’s coming up to 2 years now, and it’s still going.

Naki kouyioumtzis · Jan 12, 2020

Thanks again to this great forum for tips and help.
I had the Flashing B Display, the CL and indicators both give up on me all of a sudden, on my 2000 TD5 auto.
I removed the BCU and reflowed the soldering on the main pin/ joins, and it seems to have done the trick, so far? I will give it a test run to make sure. hopefully it’s not just a temporary fix.
The engine runs/ immobiliser is activating etc. So hopefully I haven’t done any damage?

The only one slight niggle, is the mileage display is now flashing for some reason? I guess I can live with that, although it’s slightly iterating. Does it mean something that it’s flashing?
Ps I do not have the Nanoncom yet, though I guess I probably should buy one! I wasn’t sure how long I would run the Disco for when I first bought it, so I held off. But I think it’s coming up to 2 years now, and it’s still going.

Naki kouyioumtzis · Jan 12, 2020

Thanks again to this great forum for tips and help.
I had the Flashing B Display, the CL and indicators both give up on me all of a sudden, on my 2000 TD5 auto.
I removed the BCU and reflowed the soldering on the main pin/ joins, and it seems to have done the trick, so far? I will give it a test run to make sure. hopefully it’s not just a temporary fix.
The engine runs/ immobiliser is activating etc. So hopefully I haven’t done any damage?

The only one slight niggle, is the mileage display is now flashing for some reason? I guess I can live with that, although it’s slightly iterating. Does it mean something that it’s flashing?
Ps I do not have the Nanoncom yet, though I guess I probably should buy one! I wasn’t sure how long I would run the Disco for when I first bought it, so I held off. But I think it’s coming up to 2 years now, and it’s still going.

Naki kouyioumtzis · Jan 12, 2020

Ps, I don’t know why my reply have appeared 3x. admin maybe can delete the extra ones?

Naki kouyioumtzis · Jan 12, 2020

Ps/ I just searched the flashing odometer issue. So I will need to get that reset.
I also did notice some water leakage/ condensation above the BCU area. So that’s the next thing to sort out.

Naki kouyioumtzis · Jan 15, 2020

Hmm. Well it looks like my repair did not work after all?
I went out to start it, and the flashing B is back, plus flashing M & S lights, plus bonging. Further investigation needed. It’s raining heavily so I wonder if damp is effecting things.

Naki kouyioumtzis · Jan 15, 2020

It’s not starting at all now basically.

Stanleysteamer · Jan 15, 2020

Someone else will jump on in a moment and give you some more advice but in the meantime there is a famous P clip on top of the tranny that wears through the loom and can cause shorting leading to this sort of thing. Then there is also the XYZ switch which you can take apart and clean out, then you'll need to put it back together again. There are threads on the web about both of these as they are a common problem.
Best of luck. Stan

Naki kouyioumtzis · Jan 15, 2020

Thanks for the reply.
I have replaced the XYZ switch with a new part, and soldered the wiring where it split on the P clip.
previously when i had the flashing M&S lights it did not stop the car starting? I wonder if theres two separate issues going on?

Naki kouyioumtzis · Jan 15, 2020

I guess my car is steadily working its way through every known D2 issue there is.......

Naki kouyioumtzis · Jan 29, 2020

My new Nanocom has arrived.
I have done the set up/ unlock codes on it. I think.
So here’s where I am at now.

Naki kouyioumtzis · Jan 29, 2020

I have tried to get the Nanocom yo talk to the BCU, but all I get is this message. am I doing something wrong? Or is the BCU completely dead, and needs replacing?
Has anyone else experienced this message on the Nanocom?

sierrafery · Jan 29, 2020

As long as that flashing B is on the BCU-IDM data link is failed so is the diagnostic path... also if the vehicle is immobilised it's normal to not have communication with the BCU that message is common. If you did enough research about the ''crossed B" you should know what to do, you have to replace the faulty unit, IDM or BCU it's the only way to rule one out though if you found water ingress in the BCU area and the IDM(interior fusebox) area is dry replace the BCU first, it's completely programmable, disconnect the battery first then after the swap and reconnection turn ignition on 2 let it so 5 minutes(this si valid for fusebox swap too) then go with nanocom in td5 engine menu - utility - learn security code, then in BCU settings you have to set all the options to match your vehicle's spec also to program fobs.... If you dont know how to use nanocom there are guides on theyrs site and a dedicated forum for that. Good luck

Naki kouyioumtzis · Jan 30, 2020

Thanks for the reply.

Naki kouyioumtzis · Jan 30, 2020

I am having a go at this now.
I confirm There as no water/ damp in the BCU.

Naki kouyioumtzis · Jan 30, 2020

I see the internal search function does not seem to work on this site?
I have searched on google for a how to guide on programming the BCU with Nanocom. But I have not found anything other than forum threads of people discussing whether or not to use the Nanocom or EKA codes etc.

The Nanocom site site has 20 pages of blurb, but I can’t find anything that actually shows clearly how to program the BCU?
https://www.nanocom-diagnostics.com/uploads/downloads/Discovery II Valeo BCU ECU Guide.pdf

would someone be so kind as to forward the link to the right pages of I instructions?

sierrafery · Jan 30, 2020

You'll not find a clear guide how to program it oher than how to program the keys cos the programming is vehicle dependant so after the security code was learned by the ECM you have to go through all the BCU settings one by one and select the option which fits your vehicle's specs or your personal choice for ssome features (like SPE, DRL alarm, etc) then prompt ''write settings" at the end

read that guide to understand the meaning of each setting then you should be able ro figure it out

Naki kouyioumtzis · Jan 30, 2020

Thanks.
I have tried to do all of the above.

Security settings aren’t apparently now “learned”. though the security status remains immobilised.

Key syncing is apparently successful according to the message. Yet nothing happens when I press the buttons to use it.

“Sync BCU to Odometer” Error displayed on screen.

I tried do do some of the BCU settings. They appear to be writing, but when I go back in there another time, they have defaulted back to what they were before

sierrafery · Jan 30, 2020

but after the sync did you detect it as in the video ? cos in your snapshot the procedure is not finished

Naki kouyioumtzis · Jan 31, 2020

Thanks yes. I found the You Tube guide eventually.
The car is now running again thankfully.
Oddly the M&S lights were flashing, erroneously, but I cleared the fault on the gearbox section, and it hasn’t returned.
Then I thought it was ready, but the battery seemed low, as the starter seemed to struggle? I connected a second battery. It turned over better, but didn’t start.,I activated the alarm/ locking from the fob, then unlocked again (simply as I didn’t know what else to do), and after that everything works as normal/ it started on the button . thankfully the key code was on a sticker inside the fob, as I don’t think I would have it written down anywhere else on the handbook.

thanks for your help.

Naki kouyioumtzis · Feb 17, 2020

Well, this is rather annoying.
The same issue has returned now, on the replacement BCU, after two weeks working. Am I just very unlucky to have the second BCU fail in the same way, or is something else causing this failure to happen?
I did check the fusebox. It’s bone dry/ no evidence of water.
There is some damp in the car, but the BCU itself is dry.
Any thoughts?

BCU Repair or Replace?

Active Member

Active Member

Active Member

Active Member

Active Member

Active Member

Active Member

Well-Known Member

Active Member

Active Member

Active Member

Attachments

Active Member

Attachments

Well-Known Member

Active Member

Active Member

Active Member

Attachments

Well-Known Member

Active Member

Well-Known Member

Active Member

Active Member

Similar threads