L322 (2003) No Start - CAN Bus/Engine ECU Communication Issue

Hi everyone,

I’m struggling to diagnose a no-start issue with my L322 and could really use some advice. Here’s the situation so far:

Background
1) Initially, the car wouldn’t do anything when I inserted the key.
2) Took it to a garage, and they dismantled the steering lock, thinking it was a common issue. Unfortunately, this didn’t solve the problem, and they gave up after 5 months.
3) Tried a few other garages, but none were interested, so I’ve decided to tackle it myself.

What I’ve Tried
1) Borrowed several diagnostic scanners, but none could communicate with the engine ECU.
2) Suspected the ECU might be dead, so I bought a replacement from eBay, hoping it would establish communication. The plan was to get the immobilizer removed or clone the original ECU if it worked.
3) However, the replacement ECU didn’t make a difference – still no communication with the engine ECU.
Error Codes I Can Read

Here are the codes I’ve been able to pull from other modules:
1) AT Module: Code 81 - CAN bus engine management system (EMS) timeout
2) Air Suspension: Code 32 - CAN bus fault
3) Instrument Cluster:
Code 11 - Acoustic transmitter fault
Code 8C - Auxiliary sensor incorrect
Code F8 - CAN bus fault - no DMER4 received from engine management system (EMS) ECU
Code F7 - CAN bus fault - no DMER2 received from engine management system (EMS) ECU

My Thoughts So Far

After a lot of reading, I believe the fault may be due to something pulling down the CAN network. I’ve seen posts suggesting the steering angle sensor could cause CAN issues in the air suspension, but that shouldn’t stop communication with the engine ECU.

I’ve also read that a bad battery could contribute to this. The battery was dead since the car sat for so long, but I’ve charged it. Unfortunately, it dies again after a few days. While trying to start the car, I can connect a powerful charger/booster or even jump it from another vehicle. I haven’t replaced the battery yet, as I don’t want to invest more money without knowing if the car will start.


I’m new to this and have been learning from YouTube and forums, but I have no idea where to start troubleshooting this CAN network issue.

If anyone can guide me on how to trace the fault or has experienced a similar issue, I’d be incredibly grateful.

By the way car is left hand drive if it makes a difference at all.

Thanks in advance!

Yes if the battery has sat discharged for a while and it goes flat after a few days then yes it's toast and you need a new one before you go further. If the ECU sees the battery is very low then it won't attempt to even crank and will just sit there

Look for water ingress in the left side rear quarter where a lot of electronics live.

kermit_rr said:

Yes if the battery has sat discharged for a while and it goes flat after a few days then yes it's toast and you need a new one before you go further. If the ECU sees the battery is very low then it won't attempt to even crank and will just sit there

Click to expand...

I appreciate the response, but I think the issue might be a bit more complicated. The battery holds over 12V for a few days, so I don’t think it’s entirely toast yet. If I understand correctly, the current problem seems to be something interfering with the CAN bus network, which is preventing communication with the ECU.
Without communication with the ECU, the ignition lock can’t read the immobiliser information. And if there’s no immobiliser information, the ignition lock and steering lock won’t release. That’s leaving me stuck between having no ECU communication and no ignition.
I understand that ignition uses much less power than cranking. With a powerful booster or by jumping from another diesel car, even a completely dead battery should provide enough power to reach the ignition stage. If I can get to ignition but then cranking becomes an issue, I agree that replacing the battery would be the logical next step.
That said, I’m here because I might have missed something. I’ve read through hundreds of posts and watched plenty of videos, but I want to make sure I’m covering all the bases. If there’s something else I should check or if my understanding is off, I’d really appreciate the advice!

uk_diag said:

I appreciate the response, but I think the issue might be a bit more complicated. The battery holds over 12V for a few days, so I don’t think it’s entirely toast yet. If I understand correctly, the current problem seems to be something interfering with the CAN bus network, which is preventing communication with the ECU.
Without communication with the ECU, the ignition lock can’t read the immobiliser information. And if there’s no immobiliser information, the ignition lock and steering lock won’t release. That’s leaving me stuck between having no ECU communication and no ignition.
I understand that ignition uses much less power than cranking. With a powerful booster or by jumping from another diesel car, even a completely dead battery should provide enough power to reach the ignition stage. If I can get to ignition but then cranking becomes an issue, I agree that replacing the battery would be the logical next step.
That said, I’m here because I might have missed something. I’ve read through hundreds of posts and watched plenty of videos, but I want to make sure I’m covering all the bases. If there’s something else I should check or if my understanding is off, I’d really appreciate the advice!

Click to expand...

12v is not enough for the sensors to accept the battery ... cranking will immediately drag that down, so the ECU dunt bother ...

Anything less than about 12.6 volts with the ignition on and you can forget it. 12 volts is a totally flat battery.

Problem is I am not able to turn the key so I dont have ignition on... but anyway fitted a new 12v battery which is at 12.85 volts.

Even when I unlock car and all internal lights turned on for a while it stays above 12.7-12.8v

I have checked the rear left side which has electronics as mentioned by Datatek - and I have disconnected all connections I can and all have some moisture in them cleaned up and left disconnected to check CAN network.

I tried to measure voltage at OBD port between CAN HIGH/LOW pin 14/16 this is constantly showing between 0v

The resistance between these pins is showing O.L

if the steering lock is stuck in the unlock position you cant turn the key, if its a diesel the imoberliser only stops you cranking cranking the engine, you can still turn the key, providing the chip in the key is present

badfluffy said:

if the steering lock is stuck in the unlock position you cant turn the key, if its a diesel the imoberliser only stops you cranking cranking the engine, you can still turn the key, providing the chip in the key is present

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It is a diesel I should have mentioned that - key is not turning at all - I have even tried a string lock emulator which doesn't allow the key to be turned the key is bit damaged so will try and open it up to check if transponder chip is there

uk_diag said:

Problem is I am not able to turn the key so I dont have ignition on... but anyway fitted a new 12v battery which is at 12.85 volts.

Even when I unlock car and all internal lights turned on for a while it stays above 12.7-12.8v

I have checked the rear left side which has electronics as mentioned by Datatek - and I have disconnected all connections I can and all have some moisture in them cleaned up and left disconnected to check CAN network.

I tried to measure voltage at OBD port between CAN HIGH/LOW pin 14/16 this is constantly showing between 0v

The resistance between these pins is showing O.L

Click to expand...

Not sure, but I think nothing will work on the CAN bus with modules disconnected.

you cant read the ecus properly if the ignition isnt on

Think it's fuse 18 in front fuse box if you pull it and replace it fool's the steering lock ECU and lets you turn the key just once , you could try that see if key will turn.

uk_diag said:

Problem is I am not able to turn the key so I dont have ignition on... but anyway fitted a new 12v battery which is at 12.85 volts.

Even when I unlock car and all internal lights turned on for a while it stays above 12.7-12.8v

I have checked the rear left side which has electronics as mentioned by Datatek - and I have disconnected all connections I can and all have some moisture in them cleaned up and left disconnected to check CAN network.

I tried to measure voltage at OBD port between CAN HIGH/LOW pin 14/16 this is constantly showing between 0v

The resistance between these pins is showing O.L

Click to expand...

Hi

Hope u don’t mind me saying but have u tried measuring the ohms resistance on the canbus circuit yet plse

Have done canbus testing on my D3 and was about to write them here on what pins But then thought is ur vehicle OBD2 compliant being a 2003 diesel

If it is more than happy to share what pins number are used on the obd2 socket

Was just a thought and maybe that’s why some of the scanners didn’t work

Have you got power and ground to the ecu?
If not supply your own and see if you get comms.
A later l322 I worked on that had the key near the Radio had burnt contacts in the back of the ignition barrel mechanism.
It would start in the morning when damp and then wouldnt start through the day, eventually it wouldn't start!
The key would turn and light everything up, crank but no start.
When the ignition was looked at on yours were the contacts checked in the ignition mechanism?