Please help Discovery 2 on the verge of extinction

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Hi guys. Thank you for the additonal help. Took the vehicle to the nearest landy specialist with a nanocomm. No communication to the ECU. The chap thinks that there may be a break in om of the ECU wires. He thinks this may possibly be causing the whole issue as the communication issues may cause issues with the system clearing the codes after the work was done... does this at all make sense? Does anyone have a wiring diagram for the obd harness?
 
In your first post you said...
Fuse2904 said:
Whilst doing the sump, my father in all his wisdom asked them to do brakes and front suspension. Since then the car has had the 3 amigos lit up and the handbrake light.
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From that I read that the car had no warning lights before it went into the garage, and those pesky Amigos lit when it came back (and not before).

Fuse2904 said:
Tried to read the fault codes but the OBD isn't reading on any machine, power to all the leads into the OBD and the machine lights up but no communication.
Click to expand...

As you don't have a fault code reader I assume this was done by the same garage.

Fuse2904 said:
There is a power drop between the main fuse box and the ECU drops down to 7v. When you run a second cable it continuously lights all the dash up but the lights do not go out.
Click to expand...

@sierrafery asked you some pertinent questions that you appear to have dodged, trying to determine what actions you took whilst trying to diagnose, and to clarify what you did.

Fuse2904 said:
and it is just a coincidence?
Click to expand...

I doubt it, but if you're poking around blindly with jumper wires there's a high risk of doing some damage and compounding the problem.

Fuse2904 said:
No communication to the ECU. The chap thinks that there may be a break in om (one?) of the ECU wires. He thinks this may possibly be causing the whole issue as the communication issues may cause issues with the system clearing the codes after the work was done... does this at all make sense? Does anyone have a wiring diagram for the obd harness?
Click to expand...

As the car appeared to have no problems of the electrical system before it went to the garage, I doubt the 'broken ECU' theory. The OBD harness is (from the Haynes manual) fed with 12v from fuse F20 via the purple wire on pin 16 of the OBD socket, pins 4 and 5 go to earth, data comes from each of the control units (SLABS, SRS, Cruise control, ETC, BCU, etc.) onto pin 7 (pink).
Again from memory, I think that the OBD connector is connected to all these systems via the SLABS module. Could it be that attempts to find the previous fault(s) included disconnecting the SLABS connectors. Check the location and security of these plugs.
Check pin 7 of the OBD connector is in good condition.

MM
 
Hello MM.

I didnt dodge the question, when it comes to electrical testing i have left it to my truck mechanic at work and i have been waiting for an answer from him. I have checked the obvious mechanical things but electrics arent my beat subject.

The lr specialist we saw today seemed convinced that there is any issue with the obd harness hense why i was asking for a wiring diagram to see where it tracks.
 
Can't help you with posting an OBD diagram, my IT skills aren't up to that, but see previous post from me for info on the power and data pins of the OBD socket. Your electrical geezer should be able to make sense of that.
Again, I doubt that a broken ECU wire is to blame, though it seems that to continue you must achieve OBD comms.

MM
 
Logical head now, it wasn't there before so it must be something they have done! They have replaced front brakes and suspension so the hubs would have been off. So I am thinking replace both front hubs, rings and sensors to see if the problem goes away? Or a cheap ECU in case they have fried that but I would have thought if that was the case the vehicle wouldn't start?.

Thank you in advance.[/QUOTE]
I can't think why the hubs would have been off to do this ?? That's not to say they couldn't have damaged the abs sensor leads though !!
 
Hi all bit of an update.

Had an auto electrician look at the vehicle today. Obd lead all powered up but no communication, he is suggesting abs ecu and or main ecu...

Where can i get these cheap?? Can i get these plug and play. Any suggestions please.
 
Fuse2904 said:
Had an auto electrician look at the vehicle today. Obd lead all powered up but no communication,
Click to expand...
Hi, did that electrician use a diagnostic tool which is fuly compatible with the D2 Td5 ? ...cos if it was some generic OBDII tool that might not communicate without being an issue on the data link ...
Fuse2904 said:
...he is suggesting abs ecu and or main ecu...
Click to expand...
that's another suspect thing which makes me think he doesnt know what's about cos each ECU is connected separately from a dedicated menu of the scantool so you can' just suggest it's one ECU or another eventually just the one which doesnt comunicate cos it's quite unlikely to be two faulty ECUs at the same time, there are 4 ECUs on a D2 (5 if it's auto), which one doesnt communicate???... IMO you are on the wrong path
 
The fact that the diagnostic socket has power doesnt mean that the data link is OK as well... and what kind of tool was used if it's not a secret? ... it seems that you are convinced that those two ECUs are ''fried'', do you mean that the scan tool had no comms with the SLABS nor with the ECM but it had comms with the other ECUs?
 
T4 mobile and evo pro. Quite a bit of experience. Also this is the 2nd person to plug in. The first person was dna 4x4 who could not get comms either. All wiring is good with no breaks at all. There is no comms with the car at all.
 
Fuse2904 said:
There is no comms with the car at all.
Click to expand...
That would mean that all the ECUs on the vehicle are dead as long as there is feed in the port as you said?... i dont want to insist against specialists but are you sure they checked continuity of the data link from OBD port's pin 7 and the related pins of all the ECUs?... cos i doubt that somebody went to header C0286 which is a nightmare to reach as it's wrapped into the main harness behind the fascia on the left side

Diagnostic socket diagram.jpg

C0286 RHD.jpg
 
I have just messaged him to check. If there was an issue that would lead back to wiring issues causing no comms?. Its turnung into a nightmare getting this sorted. Also i forgot to mention in my update that on top of the 3 amigos and handbrake light the box is locked in 3rd gear when in D and has m and s flashing on the dash a D flashing on the box
 
The only thing which can cause a complete lack of communication of a proper tester with ALL the ECUs (which means "the vehicle") is an interruption between OBD port pin 7 and pin 15 of that header... the 3 amigos are triggered by the SLABS ECU and the flashing M+S by the autobox ECU, the engine ECU (which i presume your electrician named "main") is not even involved in these

i've seen cases when the receptacle in the OBD port pin 7 was loose
 
Last edited:
Sounds like i would be better suited giving the landy to you haha. Ok so i have messaged him that info to see if he has tested it. For arguments sake if he has... the 2 ecus mentioned.. slabs and gearbox. Can these be ebay bought and plugged in without coding?
 
the SLABS needs programming while the autobox ECU is plug and play but it's good to reset addaptive values in it so tester is needed anyway... though i really doubt that the ECUs are at fault
 
If the slabs went down on its own could you still connect to the other 4 ecus? Would the xyz switch be in the running as having an issue also? If i was to buy both ecus used off of ebay and try the tester to program them in would that be worth a punt?
 
IMO first of all you should be certain that it's not a data link issue cos if it's that you can buy all the ECUs in vain... there are rare cases when an ECU fails as to not communicate at all while if it's that the other ECUs would communicate without problems
 
I am not convinvced the data link has been checked properly based on the reply i have had. Please could i get some advice to try this myself. I have picked up the 2 ecus anyway as they were not astronomic money.
 
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