L322 Unable to read codes after ecu disconnect

While fault finding my suspension issue, I disconnected all the plugs on the main ecu to check for any corrosion etc. The engine had been off for 15 mins and the ecu looked good as new. Ever since I am unable to read land rover specific codes. The transmit and receive lights up on my code reader but the error light also shows and no info is returned. Normal obd reader seems to work fine. I've checked fuses, tried a diff pc etc but it seems to be my fault for unplugging the ecu.

Any idea how i can fix this or am I well and truly fooked?

A standard code reader will still access the engine and gearbox ECUs as these by law have to be on a totally separate diagnostic bus to the rest of the car.

CanBUS errors are common on the L322 (and the vehicles it is based on...the E38, E39 and E53 BMWs).....The most common fault is the data signal is permanently in a high state blocking the other ECUs on the CAN from sending packets of information through.

The EAS ECU talks on the CAN to the other ECUs so I would assume your issues are with this databus. Try unplugging the EAS ECU and then plugging your diagnostics in and try connecting to the ABS ECU (which is also on the CAN) if you can connect, it is the EAS ECU at fault, if still no dice, plug it back in and then remove the Headlamp leveling ECU (this is the most common one for clogging the CAN) it is a small white box on the passenger (UK) A pillar at foot well level....it is about the size of a pack of cigarettes. This unit fails regualrly and can be left unplugged with no ill effects!.....

See if you can connect to the CAN again......

It is a case of elimination of which ECU is stuck in a high (or low) state and blocking the CAN from transmitting.

Attached is a BMW document on diagnosing the various databuses and what they do and how they work.......also on youtube is a video my the legend that is Storey Wilson (malafaxdand - or similar to that as he is known in places like youtube) and he goes through some basic CanBUS fault finding on there too.....

If the ecu was disconnected with the battery connected it might of been excluded from the system. You need to tell the system to look for the ecu & then you should be able to read it.

Thanks, but how do I tell the system to look for it?

Thanks too Saint. Found the headlight level ecu. One pin has corroded but with it unplugged the allcomms still can't read any ecu. Abs ecu disconnection also makes no difference.

Checked with eas ecu disconnected today. Still no difference. Allcomms shows error instead of linked when attempting to open an ecu. Seem to also have some electrical gremlins now too. Sat nav thinks I'm 10 miles away from where I actually am, rear window won't operate unless child lock is on and the car has a strange think of not wanting to start occasionally. Turning the key does nothing at alll but then suddenly starts to work again. I'm beginning to hate this car with a passion. Does anyone have any tips please?

K bus issues spring to mind....

How to sort I have no idea aside from Dealer level diagnostics to scope the buses as per the document I attached previously....

I assume K bus as this is what the starter/immobiliser is linked to for a security check.....

Thanks Saint. Is there anything else worth trying before? I think I was getting slight water ingress into the battery area due to a split drain hose although it might be totally unrelated. Also I think my allcomms is a chinese copy (should have guessed by the price) and the problem with reading codes started after it updated the software and didn't like it. I've reinstalled the software it came with and also tried on a diff pc but i'm unsure if this may have corrupted it somehow. All of this seems to have stemed from something simple like a faulty abs sensor

I had major databus issues from a blown headlamp bulb...they are sensitive beasts!!

There is a vid by the Legend that is Storey Wilson on K bus issues.....he suggests disconnecting fuses individually to switch off ecah ECU in turn until you can connect again, failing that....find each ECU and physically unplug them one at a time till you can connect.....

Failing that, a Dealer with the T4 Test Book can do deeper diagnostics by using the software to monitor the status of the databuses and try and isolate the problem.

Did you ever read my thread on my issues? I listed all the fuses and what I did to try and figure it out....in the end, mine fixed itself and I still have no idea what was wrong!

List is post #38

https://www.landyzone.co.uk/land-rover/diagnostic-system-failures-confused.256950/

You're a great help Saint. Thank you very much for sharing your knowledge. It is very appreciated. I'll give the fuses a bash next weekend and will also have a read of your link. I did a lot of reading of your issues previously but the more the better. Thanks once again.

Removed the ecu fuses one by one and tried to read codes when they were unplugged. Still an error each time

Can't understand why this has suddenly started happening.

What code reader are you using??

Allcomms. Tx and rx flash but within a second the error lights up too.

Which version of All Comms....the latest V3 ?

Can All Comms perform this ?

L322's are a pain at the best of times, but I'm not familiar with this All Comms system.

Usually what happens is this. The diagnostics will read the main vehicle file & save this file. You can then unplug & plug in any ecu. The diagnostics will then find that ecu & reinstate it back into the system by using the saved file. This is how ecu's are repalaced.
I need to look at this All Comms system & look at it's capabilities.

Are you familiar with this system Saint?

Rick-the-Pick said:

Can All Comms perform this ?

L322's are a pain at the best of times, but I'm not familiar with this All Comms system.

Usually what happens is this. The diagnostics will read the main vehicle file & save this file. You can then unplug & plug in any ecu. The diagnostics will then find that ecu & reinstate it back into the system by using the saved file. This is how ecu's are repalaced.
I need to look at this All Comms system & look at it's capabilities.

Are you familiar with this system Saint?

Click to expand...

I do have the All Comms Rick, it is a good piece of kit for the price.

It can't re-code all ECUs, it can do the BCU and the Steering Angle Sensor coding, set the EAS ECU into Transport Mode, set a few basic vehicle functions like daytime running lights and speed sensitive locking. Reads all ECUs for fault codes and clear them out, re-calibrate the suspension, show live data for heights, parking sensors and Gearbox Temperature.

Doesn't have functions to test inputs and outputs, i.e. Open or Close windows, flash lights or Activate the locks etc like a Nanocom or Faultmate.....but as a code reader and basic settings, it is very good.

But it can't read ECU data, save it and then re-upload to a new ECU (other than the BCU).

I have two versions of the All Comms, the older first version and then the re-released Version which is currently at V3, at times my older version won't connect and I get the errors, KC talks of, but my V3 does connect and read the ECUs.

Allcomms was bought cheap and I have a strong feeling its a chinese version. It worked fine at first but ever since the ecu disconnect it just shows error. Sat nav also still playing up and always thinks I'm at one of only two locations that I travel past on the way to and from work.