Technical 4x4 AWD not available / What might be the cause?

[BlackForest]

Hello,

No resolution so far, but some observations:

If the IBS is deactivated by pulling out the connector on the battery load sensor, the ABS is dead (cf. <NoLinNoABS.jpg>). This explains why I could observe a dip in voltage greater 0.5V when the coupling solenoid is engaging (cf. <CCMNoLin.jpg>) but could not observe a dip when observing the ABS controller.

What I did check is the ground pole on the battery. Just to exclude, that this is not resistance in row after everything.

Terminal (that is the one big ground connector) to car mass no resistance measurable when disconnected, no voltage measurable when connected. From the

False pole to battery pole no voltage drop, no resistance.

Battery pole to car mass no voltage, no resistance.

So, this part seems to be sound.

I took the battery out, charged it over night, cleaned the poles and installed everything as neatly as I can.

So next thing would be to check ground as seen from the ABS controller (anybody knows, where the Coupling Control Module is located?) to the battery pole.

Am I right, that the ABS controller (which is one part with the hydraulic block, in the MultiEcusan it is called Bosch ABS ESP 9, cf. <abs9esp.png>) uses only the mass on the connector, or is this only used for the "intelligence" (vulgo: CAN and steering signals) ?

Looking at the pin usage it looks as if this is only "intelligence":
1. +
2. speed car (from CAN)
4. signal front right
8. signal front left
13. - (ground)
16. supply sensor front right
17. supply sensor rear right
18. signal rear left
19. supply sensor rear left
25. +
26. C CAN high
27. C CAN high
28. Line K
29. signal rear right
31. supply rear left
38. - ground

If ever the "work" has its own ground, my question would be where the ground for the pump and the valves is located. Or do they use the pins 38 and 13?

Any contribution appreciated!

Thx,
David

 

[BlackForest]

Sorry, in the last posting I did not include the column headers and the description was "context german". So just for the ease of interpretation a complete version of the same data.

 

[Jerseywurzel]

I do not have a 4x4 but might I offer a suggestion?

Are you sure you had and at the beginning?
Is there a switch to change from awd to 2wd?

Just going back to basics there [emoji6]

 

[jackwhoo]

Hi , I don't have answers to you questions.
You now know more about this than most people!

I remember reading somewhere that the 4x4 system or perhaps just the electronic diff lock automatically switches off above 30kmh . There are very good reasons why it should operate like that.

You should limit your tests to low speeds certainly below 30kmh

Is abs non functional when IBS unplugged?
No abs check light when ignition first switched on?
Or abs fault light on?

Or is the edl non operational when IBS unplugged but abs brakes working?

 

[Jerseywurzel]

I do not have a 4x4 but might I offer a suggestion?

Are you sure you had awd at the beginning?
Is there a switch to change from awd to 2wd?

Just going back to basics there [emoji6]

 

[jackwhoo]

Sorry I see from data you posted edl definitely not working while IBS unplugged.
Does edl try to work , keeping wheel speeds below 30km with IBS reconnected?

I'm beginning to think IBS could be faulty causing battery control ecu shut down other ecus down to stop battery going flat. Maybe battery control ecu shuts other ecus down if IBS unplugged.

Don't know how much the IBS is but could be worth looking for a replacement ( they are very fragile so handle like they are glass)

 

[Herts Hillhopper]

I do not have a 4x4 but might I offer a suggestion?

Are you sure you had awd at the beginning?
Is there a switch to change from awd to 2wd?

Just going back to basics there [emoji6]

As a 4x4 owner, I can tell you there is no switch to 'force' 2WD, but you can 'force' 4WD (the switch - or rotary control on the Cross - offers 'auto' or 'on') The engagement of 4x4 happens automatically if wheel slip is detected (via the ABS sensors) and this activates a solenoid in the rear diff to engage the rear drive.

 

[Herts Hillhopper]

BlackForest jackwhoo
This does seem to be a recurring fault in the 4x4 models. You may already have read these two threads, but if not they may provide some insight. I think there are others too but these two came up from a very quick search:

https://www.fiatforum.com/panda-iii/457985-panda-4x4-not-working.html - the solution is in post 13 (but note people carried on offering advice after the problem was fixed)

This, from the older 169 model, but where the Cross version used the same rear diff as the present model: https://www.fiatforum.com/panda/175397-panda-cross-4x4-system-failure-update-3.html

 

[jackwhoo]

BlackForest jackwhoo
This does seem to be a recurring fault in the 4x4 models. You may already have read these two threads, but if not they may provide some insight. I think there are others too but these two came up from a very quick search:

https://www.fiatforum.com/panda-iii/457985-panda-4x4-not-working.html - the solution is in post 13 (but note people carried on offering advice after the problem was fixed)

This, from the older 169 model, but where the Cross version used the same rear diff as the present model: https://www.fiatforum.com/panda/175397-panda-cross-4x4-system-failure-update-3.html

I did get a bit confused reading those threads, but first thread problem fixed by a fiat dealer doing something to an ecu (maybe)

Second thread more interesting ,
Failing coupling valve on rear diff
Giving 4x4 not available message on dash.
I looked up valve part number in thread and it looks like only 40 euros, could be worth a go as so cheap.
solenoid valve is: 55228875

 

[Herts Hillhopper]

I did get a bit confused reading those threads, but first thread problem fixed by a fiat dealer doing something to an ecu (maybe)

Second thread more interesting ,
Failing coupling valve on rear diff
Giving 4x4 not available message on dash.
I looked up valve part number in thread and it looks like only 40 euros, could be worth a go as so cheap.

I agree - and I think replacing that part would have been my first action... the battery side of things has been very interesting but I suspect is an unrelated issue. I presume that even after replacing the valve, there may be a fault code to clear?

 

[jackwhoo]

I agree - and I think replacing that par would have been my first action... the votary side of things has been very interesting but I suspect is an unrelated issue. I presume that even after replacing the valve, there may be a fault code to clear?

David is getting super efficient with his mes so I'm sure he can clear any fault codes.

I hate part swapping unless confident part faulty but sometimes the only way to know is to change the part.

As far as I know David is not getting any stored fault code for why message 4x4 not available which is not helping.

I am sure David will beat the problem and looking forward to his win and knowing root cause.

Cheers
Jack

 

[BlackForest]

...
Does edl try to work , keeping wheel speeds below 30km with IBS reconnected?
...

Valid point with the 30km/h. The question wether one wheel above is sufficient aside, I have evidence, that the problem occurs at lower speed :-(

ELD was deactivated in that test anyway.

BTW, to my understanding, 4x4 is well active above the 30km/h. It is only the ELD which ceeds the place to ESC above that speed.

And furthermore we see in the data of the sheet attached, that there is no voltage dip when the coupling control solenoid is (because ELD is deactivated) is not active.

For the very moment I think I will check the "mass band", this device linking the body to the engine. And then I will shop for the coupling valve.

Thx for all of your contributions!

David

 

[BlackForest]

And what is really, really weired is the fact, that the valve causes a voltage dip, but not so the pump!

In my tests I did the same for all of the valves (8 ABS, 4 ESC, 1 Coupling Control) and they all had the same pattern of a voltage drop when actuated.

Can't remember how this was with the pump. Will have to repeat this one.

Thx,
David

 

[jackwhoo]

And what is really, really weired is the fact, that the valve causes a voltage dip, but not so the pump!

In my tests I did the same for all of the valves (8 ABS, 4 ESC, 1 Coupling Control) and they all had the same pattern of a voltage drop when actuated.

Can't remember how this was with the pump. Will have to repeat this one.

Thx,
David

I have read the thread again and the fault condition of some of the abs/edl valves jump out at me .
Do you know if the 4x4 not available message happens at same time the abs/edl faults happen?

 

[BlackForest]

Did check my logs:

4 ABS Load valves caused a drop from 12.26V to 12.07V
4 Traction valves caused a drop from 12.26V to 12.07V
4 ABS Drain valves caused a drop from 12.26V to 12.18V
ABS-Pump caused a drop from 12.26V to 12.18V
Values are per valve. Concurrent actuation is not possible, so I can't tell you what happens.

The coupling control solenoid valve caused a drop from 12.315V to 12.189V as documented in the screenshots already posted earlier. (<on.png>, <off.png>)

NOTE: The screen showed shortly a deeper reading and in the recordings (also posted earlier) we see a dip in the magnitude of >0.5V.

Thx for your attention!

 

[BlackForest]

new coupling valve is ordered!

Stay tuned ...

 

[Panda IIs]

new coupling valve is ordered!

Stay tuned ...

Still tuned; intrigued to know what happened?

 

[Jerseywurzel]

Yes, me too

Still tuned; intrigued to know what happened?

 

[BlackForest]

:-(

Did take a while - to no avail. What happened?

First I did replace the valve. Much the same behaviour. So it was not the valve.

General Problem: Could have measured that - if there where any points to tap into the circuit - into the circuit as it lives. But it is closed. So no way to measure the voltage from the valves mass to the battery as the valve is working. And the resistance, which could be measured if the valve is disconnected is hard to interpret if you don't know the resistance of the intended workers in the line. Remember 40Amp fuse with 12V we are talking about resistance near to nothing that counts. But how much nothing is worhtwhile an effect?

Then I went to the fiat dealer. Old story: "We have the best OBD, we can see what the others don't see, trust me". Well, they even couldn't see the errors the Multiecuscan reveils. And they can't log the behaviour while the car is running - no way to reproduce the fact. And they can't actuate the valves - probably for security reasons, as releasing the pressure on the brakes is something that can be dangerous if done in the wrong moment.

Well and then they did what they (we) all do: Without measuring anything they cleaned blindly the mass points. To no avail.

So I am left with the confirmation, that it is by design: You are not supposed to fix electric problems on modern consumer devices (such as cars). Where the computer can't overtake the burden of reasoning you should put the device in question into the disposal unit ...

Well you see me somewhat clueless and demotivated. But we will come back ;-)

Will have to invent something to measure from the coupling valve to the battery mass in vivio and ...

... to identify the fuses for the ABS and the Coupling ECU and ...

... to measure from the load side of these fuses to the batteries mass in comparison to what the ECUs see as the valves are operated and ...

... wether there is a (significant) voltage drop on the fuse(s).

My guess for now is, that both ECUs are on the same fuse. As far as I know, it is a 40Amp japanese fuse. No clue how to get this thing out to confirm it is the right one ...

Thx for your compassion!

 

[varesecrazy]

I'm disappointed for you

A lot of effort.. and significant cost.. with no great improvement...

Charlie