Discovery 2 td5 electric problem

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So i check 85 to ground and then turn the switch and do the same for 86 correct?
Shall i also check continuety between the BCU ands the relay contact which connects to the bcu 85 or 86.
Also the red white from the passenger fuse box does it connect to 85 or 86?
 
Does the red white from the fusebox passenger compartment connect to 85 or 86.
Also for the black orange from the bcu does it connect to 86 or 85 just to check continuety of these wires.
Do i check 85 and 86 to earth when i turn the ignition switch?
 
You check voltage across earth and 85 while ignition on crank and if it's 12V across 85 - 86 , if no 12V it means the live is missing if it is then the earth, i cropped the relevant part of the diagram to make it easy for you, for the connectors check RAVE - Electrical library connector views , for example you see that the black/orange(BO) wire comes from BCU C0662-5 see C0662 in connector views cos it's everything there, the white/red wire from ignition comes to C0573-5.... if the earth doesnt come on that wire from the BCU it can be interrupted wire but if it's not that it can be problem betweeb C0571-2 and the relay's cavity within the fusebox or a BCU internal fault cos as long as it started with bridged relay it's not immobilised so cut that wire near the BCU and connect it to earth, if it was BCU it will start if not it's the fusebox.

D2 starter relay circuit.jpg
 
Thx. I will check later in the week when it is not raining. Firts check c0662-5 when connected to earth and than start. I will also check continuety between this point and the fusebox in th enginebay. I need to find the C0573 connector wire 5 and 7.
Thanks again for the help, hope I can return a favour in the future.
 
That's good but you also need a nanocom or similar to program it otherwise it will not work.... C0573 is on the back of the fusebox, check RAVE - electrical library connector views, if you dont have RAVE download rave01.iso from here http://www.green-oval.com/data/lr/
 

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Thx found the connector, I have the rave. Yes I also hav a Nanocom evolution so I can enter the BCU. By programming you mean setting all the settings as in my existing BCU and programming the key code that are in the existing BCU in the new BCU and following the key sync procedure or is there something else to look for.

I will first connect the pin on the BCU to earth C0622-5 and see what that brings.

Thanks again.
 
So new morning new possebilities. I checked continuatie from the fuse 23 (ignition signal) to the fuse-box in the enigen bay, it shows 12 volt when key is turned. Then checked the other relais contact to pin number 5 of the BCU connector C0662-5 and when turning the key there was 12 volt on pin 5, so there is signal coming to the BCU. Then connected the pin 5 to ground and the engine started.

I then checked the read-out on the nanocom for the inputs of the BCU. on Body 1, inertia = set, ignition in, transfer / neutral is off. park/neutral is off (when switching gear selector to reverse it goes to on) on body 2 transfer neutral is always off when shifting gear selector from park to 1 and back the same goes for the park / neutral switch.

All XYZ change state when going through gear selection so seems to be working fine.

Don't know if this helps just as info for fault finding.

So is it as state to which the BCU concludes engine should not start or is the relais in the BCU busted?
 
Seems very like BCU fault cos if the BCU as you say concludes that the engine should not start it cuts the starter + the ECU's security code so the engine should not fire even if you force crank it with bridged relay if you see what i mean.... don't torment yourself with other measurements untill you dont rule out the BCU, for test it's enough to program the starting protocol for the replacement BCU which means to connect to engine ECU -Utility - learn security code and set the BCU to automatic and diesel.... then if it starts you can load all the other settings in it which you can save from the old one but if it's fubar it might not be the best
 
I am learning al kinds of English her, what is fubar?
Where do I find the Enigen ECU Utility - I expect under Engine ECU and then Utility. is it stratight forward? I have downloaded my old ECU setting soem time ago as a prepacution so i have an older file. I know all my key code so no issue there.

And agin thanks for the guidance is realy helps.
 
about fubar: http://www.urbandictionary.com/define.php?term=fubar :cool:

Utility is in the Td5 engine section of nanocom, the ''learn security code'' is compulsory if the engine ECU or BCU are changed
(Utility)
· Learn security code: When the ignition is turned on, the BCU or Alarm, providing it is in
receipt of a valid transmitted Key Fob code and is therefore not in an alarmed or
immobilised state sends a coded data transmission to the TD5 ECU. The TD5 ECU then
decodes this data and compares the code contained in it against a mobilization code it
has stored in it. If the two codes compare OK, the TD5 will allow the engine to start.
This forms the basis of the immobiliser. If the TD5 ECU, the BCU, or the Alarm is
changed, it may be required for the TD5 ECU to re-learn a new mobilization code. This is
done by using this function to put the TD5 ECU into Security learn mode. After setting
the TD5 ECU into learn mode it is required to turn off the ignition for 15 seconds, then
back on. Receipt and acceptance of a valid code can be verified by viewing the
'Immobilisation Status' in the 'Other' section.

you can download nanocom user guides from here https://nanocom-diagnostics.com/downloads
 
Oke, Thanks, A have a spare BCU form a car that is from the same year, software level is the same so should work. I will swap it ans ee if it start after learning and then do all the other bits of settign it up key's and all. I do have to find the EKA procedure as i have not looked at that yet.
 
Oke so swapt the BCU, Set the ECU to learn code mode, waited 15 seconds etc. looked at the security state and it stated NOT IMmobelized. So i expect it to turn over. Nothing yet. I copied all the code from my old ECU to the new, went oke. MAde sure i entered the right keycode and connected the fobs also no iussue there both keys wok fine. I looked at ethe info of the BCU and found the VIN to be not my VIN. typed in my VIN, write it, read it back and it seems to be in the memory. Than when i go back a few steps the VIN reverts to the VIN of my new ECU????

Trying to start the engine, it will not start, bridge pin 5 on the BCU to ground and the car starts and keeps on running.

So my conclusion is it is not the BCU, there must be a signal sequense that is leading the BCU to not allow the enige to start.

I am lost for words.
 
Another lione of attack. I checked the BCU input sections for Body 1 and Body 2 and also the Engine ECU for Park Neutral positions
upload_2017-9-19_17-10-27.png

Is it correct for the Body 1 to have the P/N constant on off where in Body 2 and on the ECU it is clearly detected when shifting the gearlever.
I checked this as 2 weeks ago when i shifted the lever back and forth the engine did start.
 
At lest the BCU is ruled out now, then it might be some interlock which comes into play but i dont have much experience with autos, are your M + S light working on ignition self test? cos if you played with nanocom it used to have a mind of it's own in the BCU and alter settings so make sure in "TRANSM_LOCK WARN" it's not set to manual transmission cos then it will not start
 
Settings all seem to be correct. checked twice. All self test lights work no issue there. What i do know is that 4 weeks ago i had this issue 1 per week and it got progressifly and no it does not start with-out shorting pin 5 on the BCU to ground.
I need to find somebody that knows the interlock states to rule out any of these.
If you know anyone please link them in the tread.
 
This is a very ugly defect cos it's completely out of any path, it can be a misscommunication between the IDM(interior fusebox) and BCU even though then it should be immobilised which is not, if it was a XYZ fault it should have triggered the flashing M+S warnings as well, it's certain that the BCU is missing something but i can't imagine, what, i suspect the P/N input which should be earth to BCU C0663-11, so chek if there is earth there when P is selected cos if it's not that's the problem, then it can be a wiring issue between the XYZ switch and BCU or within the switch if there isnt earth with P selected at C0675-5, it's a BG wire all the way but it goes through a connector under the console and a header so might be that path

the gist is in this part of the BCU's operation i suspectbthat autostart inhibit cos all the others would trigger an immobilised status:
Starter relay
The BCU checks the status of the following inputs and internal BCU conditions to determine whether or not to provide
an output to enable the starter relay:
l Autostart inhibit (vehicles with automatic gearbox only).
l Security start inhibit (immobilisation check).
l Engine running (link to instrument pack).
l EEPROM locked (internal check).
l IDM and BCU matched.
When the BCU receives a crank signal from the ignition switch, an earth path is completed to the starter relay coil,
provided that the security system has been de-activated. If the ECM has not received a valid unlock/ remobilise signal,
the starter relay will be disengaged and the engine stopped. The BCU also receives an engine running signal from
the instrument pack, so that if the ignition key is turned to the crank position while the engine is running, the starter
motor relay will not be engaged.
If the logic conditions are correct to allow starter operation, the completion of the earth path from the starter relay coil
to the BCU energises the coil and the relay contacts close to supply battery power to the starter motor.
When the ignition switch is released from the crank position, the power supply feed from the ignition switch to the
starter relay coil is interrupted and the relay contacts open to prevent further battery feed to the starter motor.
If a communications link failure is experienced, the BCU will be prevented from detecting the 'engine running'
condition and the BCU will default to assume that the engine is not running.

On C0663
 
The M&S are not on. the last i tried this evening was removing the cover on the gear selector switch (center console), wiggled this around and than i could start the engine 3 times before it did nit again tried this once more and it worked again after this no luck. so will have to look there as in your latest you state something about the console. i will check the earth on pin c0663-11. this will not be before the weekend so i will finish for now
 
I know this is an old thread but I thought I would add to it in case it helps anyone with a similar fault.

After swapping an XYZ switch from a known working Disco2 and then diagnosing that we had a faulty BCU, the BCU was replaced.

Although the XYZ switch had been set up manually by rotating it until a position was found where the auto box gear position indicator lights lit up correctly, the Disco wouldn't crank over when trying to start, despite showing no M&S or immobiliser lights on the dash,

Earthing the low current side of the starter motor relay in the engine bay fusebox allowed the starter to crank when the ignition was turned to the cranking position and the engine to run as normal.

As @sierrafery identified in reply #38 above, the BCU will only allow the starter to crank if a series of conditions exist.

And exactly as @sierrafery had suggested, the symptoms pointed to a problem with the immobiliser switch earth.

"so chek if there is earth there when P is selected cos if it's not that's the problem, then it can be a wiring issue between the XYZ switch and BCU or within the switch if there isnt earth with P selected at C0675-5, it's a BG wire all the way but it goes through a connector under the console and a header so might be that path"

The key learning for me was that there is a separate switch inside the XYZ switch body which immobilises the starter unless the gearbox is in P/N. Do not assume that just because the gearbox selector lights/in dash gear position display correctly show P, that the separate starter immobiliser switch will be in the correct position.

The XYZ switch needed rotating very slightly to find a position where both the starter immobiliser switch and the XYZ switches all opened/closed correctly.

The status of the Park/neutral switch can be checked, along with the XYZ switch positions on a Nanocom, under the VALEO BCU/READ INPUTS/BODY2 menu.

DO NOT ASSUME like I did that because the P indicator was lit up on the gear shift / in the dash display,then the starter inhibitor logic built into the BCU will be OK !!!
 
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