C5 X7 faulty BHI?

[Monad]

Hello all,

I've recently taken on an '08 X7 Tourer that was going for reasonable money (or perhaps it's just a form of madness )
Engine and Gearbox are sound, but the hydraulic systems doesn't respond to cabin commands and the car is showing "Suspension Faulty".

I'd managed to get it home, gently, and I'm getting stuck into resolving the issue.
The diagbox session I ran when inspecting it revealed the following codes for the suspension ECU:

U1116 x2
U1117
U2005

I've come to understand from browsing a few threads on the topic that these codes aren't uncommon, I've had the front body position sensor out of the car and tested on a bench that it is powering up, and with diagbox monitoring the suspension ECU parameters - both filtered input from the front and rear sensors show "000" with no reaction when manipulating the front sensor.
(I'd pre-emptively ordered a new one on the off chance it was a simple as that, d'oh).

All fuses appear to be intact in the relevant locations, with the original 40A fuse in place for the Hydractive system.
I can hear the solenoids clicking when testing in Diagbox, and when I run the pump test it spins for a second or so and stops.

I've checked the connector for the suspension ECU and the pins appear to have some gunk in them, perhaps some gelled up LDS?

In short, I've convinced myself in the course of writing this post that I think I need to get a new BHI, is there anything else worth trying or checking before I pull that trigger?

Thanks!

[GiveMeABreak]

U1116: Suspension ECU data not valid fault: Protocol controller not functional. This basically means the CAN controller for this circuit is not working.
U1117 is only for V6 and 2.2 vehicles with suspension separate ECU - so shouldn't be relevant to a 1.6.

[Monad]

Hi Marc,
Thanks for that - so what I'm getting is a load of nonsense from it, and a replacement is probably in order?
Not sure what you mean by "1.65" though, the VIN if useful is VF7**************[VIN obfuscated, can be read by forum staff].

[GiveMeABreak]

A typo - I meant 1.6 as in engine size, which only have the built-in suspension ECU within the BHI, and not the separate CDD suspension computer for V6 and some 2.2 models. An d of course I looked at your topmost vehicle list to note the 1.6 Tourer you have, but same applies for the 2.0.

Ok, so with the VIN this helped as this is a general communication fault code (U1117) and can appear on several systems that are interlinked. I checked the ABS / ESP and this is coming up there as a fault. Diagbox should have listed the system where the fault was detected in order to narrow it down, so I can only list the code under the ESP system. U2005 is a normal ghost fault that appears when the suspension ECU is interrogated by the diagnostic tool.

Fault Code:	U1117
Description of Fault:	Fault no communication with the intelligent hydraulic unit ECU: No signal. The time of appearance of the fault code is 2s. No transmission of datastreams by the intelligent hydraulic unit ECU.
Conditions for Fault to clear:	Transmission of datastreams by the intelligent hydraulic unit ECU
Downgrade Modes whilst Fault is active:	No back-up mode
Symptoms:	-
Suspect Areas:	CONNECTORS Line CAN ESP ECU

[Monad]

Aha I see. Thank you for the further detail, I'll dig in some more before I call our local specialist.

[Monad]

Had another look today, and sure enough the global test shows U1217 under the ESP ECU as well.
I've removed the BHI and will try to source a replacement for a next step.

[Monad]

It took a while for it to occur to me - the pump is operational, and the electronics respond during testing.
Exactly as Marc had said, U1117 doesn't make sense to occur on my car - I've re-installed the BHI, checked it's coding and it was set for the incorrect engine type.

After refilling the car with fluid and bleeding, the back end rose up immediately, but the front is still yet to rise much.
A brief pogo-ing drive up and down the road and sure enough the front body sensor is now reporting as faulty.
Good job that replacement is on the way

[GiveMeABreak]

Great, well done and thanks for taking the time to update the thread.

[Monad]

Just following up to close this thread off,

After the BHI being reprogrammed, the ride was terrible as well as the normal ride height being off.
I've just swapped both front spheres and it's now driving wonderfully - and the new ride height sensor has just landed in the post.
A bit more tinkering and I think we're there.

I wouldn't have been able to get this far without the knowledge documented throughout the forum - so thank you all.

[Sloppysod]

Hi Guys, Am I looking at the same issue as Monad?

During pre MOT Checks and servicing I have a few faults still present:-
Re Electronically managed suspension
U1118 - Fault: absence of communication with the Built-in Systems Interface (x2) , Intermittent Fault - Communication error?
U2118 - Triggering (height adjustment receipt anomaly) , Permanent Fault - Communication error?
U2005 - Triggering (vehicle speed receipt anomaly) , Permanent Fault - Communication error?

History.

• The U1118 faults were first seen a few months back, see viewtopic.php?t=76359&hilit=U1118. As all the other faults were cleared and did not return again I never followed it up .

• I fully depressurised the system with Diagbox to help me check suspension joints. However, this did not go as planned, I now have more than 150ml of LDS that I managed to catch as it spewed from the reservoir. Previously I had only checked the level by lowering the car to the lowest setting. The stuff I did not catch covered the pump and its BHI, both of which were wet prior to this!

• Prior to fitting 3 new front Spheres I have ordered, I thought I would also check the heights. I seem to be about 20mm high front & rear and I'm hesitant to change this because, (a) I have never had to adjust the rear, (b) I only adjusted the front a few years back when things got knocked while changing the rack, and (c) the car looks right

The U1118 has been around since May 2023, the U2005 has been around since December 2017 and the car drives okay, apart from not being as smooth as it should?
Any thoughts would be appreciated.
Thanks

[GiveMeABreak]

Ignore U2005 Stu. That's a phantom fault as a result of the suspension ECU (contained within the BHI) being interrogated.

U2118 is an ECU partial triggering fault - that is on the intersystem CAN network - but this is a generalised CAN fault and can appear on different ECUs, but in the case of Diagbox it has pointed this specifically towards the suspension height. As the height sensors on this vehicle are just analogue sensors, the fault is likely to be with the BHI having an issue reading the data correctly. That could indicate some issue between the sensor wiring and the BHI. Given that you've already noted some contamination with LDS leaking onto the BHI and mentioned it was wet already, I would be looking at ALL the BHI connectors, pins and sockets and giving these a good clean up with electrical contact cleaner as a first check.

Fault Code:	U2118
Description of Fault:	Intersystem CAN network: Request for partial ECU triggering not plausible or absent. Communication fault between ECUs detected for 3 secs. Conditions of activation of the diagnostics The following conditions have to be met: - Engine running - Ignition on
Conditions for Fault to clear:	Driving with the engine hot for 5 minutes
Downgrade Modes whilst Fault is active:	-
Symptoms:	Engine hesitating, cutting out Lack of power Starting problem
Suspect Areas:	Engine ECU Intersystem network

Fault Code:	U1118
Description of Fault:	Intersystem CAN network: Loss of communication with the ECU BSI. Communication fault between ECUs detected for 3 secs. Conditions of activation of the diagnostics The following conditions have to be met: - Engine running - Ignition on
Conditions for Fault to clear:	Driving with the engine hot for 5 minutes
Downgrade Modes whilst Fault is active:	Reversible deactivation of the vehicle speed limiter, cruise control and speed curbing functions when there is an engine information fault. Irreversible deactivation of the vehicle speed limiter (Need to switch the ignition off and then on, in order to make the function available again). Deactivation of the tight spot for the cruise control. Reversible deactivation of the vehicle speed limiter. Reversible deactivation of the vehicle cruise control. Reversible deactivation of the vehicle speed limiter, cruise control and speed curbing functions when there is a transmission information fault. Reversible deactivation of the vehicle speed limiter, cruise control and speed curbing functions when there is a vehicle information fault. Switching on of the warning lamp and/or warning message: Warning lamp MIL
Symptoms:	Engine hesitating, cutting out Lack of power Starting problem
Suspect Areas:	Engine ECU Intersystem network

[Sloppysod]

Thanks for that Marc, I have been with the car all day, and now having a rest now.
Had planed to look at the BHI connectors, but forgot, will do tomorrow morning though.
I am suspecting a front height corrector as I have noticed that sometimes when sitting at the traffic lights the car will suddenly correct the front height by lifting the front about and 1" or so.

I think the previous height settings I calculated may have been incorrect and the car was possibly in the Normal+1 position
I have run every suspension actuator test without any failures or error messages - So I assume that any problem is no longer visible - for now
I cleared all the faults and took the car for a 'vigorous' test drive, I found some really potholed roads, in normal mode, normal+1 and sport mode in both - no faults on return.

First thing this morning I checked front and rear suspension heights, engine ticking over, hand brake on!! Front was 169mm, Rear Was 76mm, not bad but still wrong!
After the test drive, I measured the heights again, this time, Front was 173mm, Rear Was 87mm, so they still need adjusting.

Questions
When the car gets a error in either height corrector, does it go into 'Safe' mode by either, raising the suspension a little or default to sport mode?
Also, not sure why the two measurements from today are different, I can only think it being either the "handbrake on" and/or the "Suspension cold" vs "handbrake off" and/or "Suspension warm".
Would, having too much LDS in the tank make any difference?
I done a bounce test this morning, suspension cold, and I thought my diagnosis regarding new spheres was wrong, but when I done another with the suspension warm, I think I was right, would warm suspension make a difference?

Now I have a problem what setting do you adjust in Diagbox from the Height setting option?

• Front & Rear Setting Height

• Front & Rear Filtered Height

• Front & Rear Reference Height Programmed

• Initial Front & Rear Reference Height

viewtopic.php?t=81842

[PaulC5]

'I am suspecting a front height corrector as I have noticed that sometimes when sitting at the traffic lights the car will suddenly correct the front height by lifting the front about and 1" or so.'

Our 2007 C5 does this sometimes but I find greasing the height sensor pivot joints seems to stop it happening for some time.

[GiveMeABreak]

No this is normal operation and is referred to as hysteresis, so don't go adjusting on the basis that those measurements are changing because of this function:

During normal operation, for a selected body height, the integrated hydraulic block corrects the ground clearance in the following cases:

• Difference between the front or rear height and the reference ride height more than -4 mm and 4 mm (hysteresis)
• Difference between the front height and the rear height more than 8 mm

The function takes into account the average height of the body in order to eliminate "interference" and filter the current travel values.

A timed period referred to as the "dashpot" is applied between the time the system detects that the body is outside the hysteresis zone and the time when the height correction comes into operation, in accordance with the conditions below:

• On starting, a timed period of 0,5 second, when the driver requests a change in height or when the integrated hydraulic block ECU is triggered for "height correction"
• When the vehicle has been driven and becomes stationary with the engine running, the timed period is 60 seconds

In the other cases, the timed period is 10 seconds

Note: The height can only be modified when the suspension stiffness pattern is in "soft" mode.

You can't change the reference heights Stu as these are programmed at the factory for comparison against the actual ride heights.

Regarding back up modes:- yes, there are values that will be applied or functions set to limits or inhibited, depending on what the fault is or what info is deemed incorrect, but these are quite complicated as they depend on multiple factors, for example restricting height correction, stopping road condition monitoring, deactivation of hydractive function etc.