L322 When should the EAS compressor run?

Datatek said:

Swapping parts or leaving things disconnected is not a good strategy on the L322 because so many ECU's are interconnected. Designed by the Marx brothers

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Then how else can it be diagnosed? Apart from ripping the car to pieces and checking every length of wire? I have a very odd fault. Most people with this problem also have other lights on. I can’t communicate with the ABS and Air bag modules. Yet I can talk to the rest. You will note from other threads disconnecting them has solved the issues for other people.

Tried the replacement ABS ECU, still no luck. running out of options now!

Right,

Did a test on the K Bus wire today at the EAS ECU. I have 12v, and it rises when the RR is started

So, tried pulling each fuse. Has no effect. Also the 12v is static regardless of ignition on or off! Does anyone know where in the car the joint X10466 and X10116 is? I see from a google X10116 on the BMW is above the fuse box. done know if the range rover is?

EDIT: My steering column lock doesnt engage too ive noticed. Seeing as this is controleld by the BCM, the BCM is on k line. Also i presume the BCM must be live all the time for the central locking?

K-line will always show 12v with a multimeter but that doesn't mean that it is communicating.
You need a scope really to see if there is any activity on the bus.
https://www.picoauto.com/library/automotive-guided-tests/k-line/

Wazzajnr said:

K-line will always show 12v with a multimeter but that doesn't mean that it is communicating.
You need a scope really to see if there is any activity on the bus.
https://www.picoauto.com/library/automotive-guided-tests/k-line/

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Yes, k line should have more than 7 volts according to this document
http://www.mdv.se/bmw/bmw sheets/ibus.pdf

But less than the system voltage ie 12.

When I start the car it rises to 14v which is why I’m sure I have a B+ short somewhere.

More than 7v required for operation but should be close to nominal voltage so your voltages are fine.
You need a scope on it really to see if there's any activity on the bus.

t20bigjim said:

Yes, k line should have more than 7 volts according to this document
http://www.mdv.se/bmw/bmw sheets/ibus.pdf

But less than the system voltage ie 12.

When I start the car it rises to 14v which is why I’m sure I have a B+ short somewhere.

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If it's 12 volts engine off, it will rise to alternator output voltage engine running.

Wazzajnr said:

More than 7v required for operation but should be close to nominal voltage so your voltages are fine.
You need a scope on it really to see if there's any activity on the bus.

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Seeing as I can’t access EAS, Air Bag etc I’m guessing the bus is down. As I’ve tried all the usual suspects it’s now down to the plain unusual.

My snap on verus does have a scope facility. Never used it so now is time to learn

Datatek said:

If it's 12 volts engine off, it will rise to alternator output voltage engine running.

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Yup. Just put a scope on it. No matter how small I make the sweep, ie 500 micro seconds I can see no activity on the k bus. Tried ignition switching on, starting, using components. So I’m still convinced something is blocking it or it’s shorted.

Hi

Don’t know how helpful this will be, can u do a continuity test on the loom to ensure there’s no breaks anywhere or bad connections , ie dirty / broken pins

Also earth points tested

So then u know at least the loom is ok

gstuart said:

Hi

Don’t know how helpful this will be, can u do a continuity test on the loom to ensure there’s no breaks anywhere

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I’ve done various tests. Checked wiring from EAS to instruments and it’s complete. The ABS and EAS I can’t talk to are both on K line. I can talk the the ABS, SAS and engine/transmission.

t20bigjim said:

Seeing as I can’t access EAS, Air Bag etc I’m guessing the bus is down. As I’ve tried all the usual suspects it’s now down to the plain unusual.

My snap on verus does have a scope facility. Never used it so now is time to learn


Yup. Just put a scope on it. No matter how small I make the sweep, ie 500 micro seconds I can see no activity on the k bus. Tried ignition switching on, starting, using components. So I’m still convinced something is blocking it or it’s shorted.

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500 micro seconds is a lifetime in electronic terms, but I don't know what the speed of K line operation is. However you should see something, the problem will be triggering the scope sweep to coincide with any activity.
The trouble with all these interlinked systems is that one component failure can bring the whole system down

t20bigjim said:

I’ve done various tests. Checked wiring from EAS to instruments and it’s complete. The ABS and EAS I can’t talk to are both on K line. I can talk the the ABS, SAS and engine/transmission.

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Thks, assumed u had, shame there’s not a test sheet to show what voltages etc u should be getting back and outputs , are ur earths also sound

Have u checked live data or will it simply not allow u to read anything on the ads/ eas

What diagnostics have u tried plse , is ur obd socket ok, no breaks etc

What year is ur rangie plse

@t20bigjim

Have u seen this https://www.landyzone.co.uk/land-rover/can-bus-errors.301407/

Also just found the video , hope it helps

So, your next move is to disconnect every ecu on the bus bar one and see if it then has any activity. If not, try with that ecu disconnected and one other connected.
It is unlikely that two will be faulty.
If you still see no activity its down to the wiring.
If you do see activity, plug back one ecu at a time until it stops again and there lieth your fault.
Hope that makes sense!

Wazzajnr said:

So, your next move is to disconnect every ecu on the bus bar one and see if it then has any activity. If not, try with that ecu disconnected and one other connected.
It is unlikely that two will be faulty.
If you still see no activity its down to the wiring.
If you do see activity, plug back one ecu at a time until it stops again and there lieth your fault.
Hope that makes sense!

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Thanks.

Does anyone know, is the k bus live with ignition switches off? It really REALLY would help to know

Done a can bus scope test. Can bus has a perfect waveform,

K bus has a static 12v line with the occasional blip down to 0.



Any thoughts on why this is?

Went to find BCU under passenger seat and found the header I’ve been looking for! It’s the x10466. Tool all connections off. Tested wire to EAS, it’s fine. Found feed from the other header wherever it is! Connected just the EAS and still couldn’t communicate!

This is the header, located next to the BCU.

Hi T20bigjim

Did you get to the bottom of this, and if so what was the resolution? - I think I have the same issue and have headed down the same path as you, so any help would be amazing.

Cheers

Neil.