C5 x7 2.7 suspension error

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chris_reade
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C5 x7 2.7 suspension error

Post by chris_reade »

Good afternoon

I have a 2008 C5 X7 Tourer. Briefly, took to a mechanic (miles from a dealer unfortunately) to have some bushes replaced. Mechanic failed to open the LDS tank, and when he lowered the car off the jacks it sank down and stayed down. Pump inoperative, and getting a suspension ECU communication error.

I had it recovered to a mechanic who knows what he's doing and has a Lexia.

Suspension pump was failing due to previous LDS infiltration, so we've replaced it with one from a 3.0 C6 and coded it. Also replaced LDS tank.

Pump now activates but communication error with suspension ecu still there, and car won't rise.

I will ask him for the exact code, but in the meantine he would like to know the precise location of the second suspension ecu which this vehicle is supposed to have in the rear somewhere.

Also any circuit diagrams pertaining to the suspension system would be greatly appreciated.

VIN VF7**************[VIN obfuscated, can be read by forum staff]

Thanks in advance. Aren't C5's fun?
Kees
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Re: C5 x7 2.7 suspension error

Post by Kees »

You don't tell what kind of engine you have, because the pomp from a 3.0 has a different suspension system.
Not only the BHI on top of the pomp, but also a ccs computer.
This last one is connected with the 4 height sensors.
So if you don't have a V6 petrol/diesel the you should use youre BHI from the tourer.
Greetings,
Kees.
Kees
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Re: C5 x7 2.7 suspension error

Post by Kees »

The location of the CCS ecu is on the left side, on top where the fuses are.
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GiveMeABreak
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Re: C5 x7 2.7 suspension error

Post by GiveMeABreak »

He has a 2.7 V6 Kees (in the title of the Thread :-D )
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Marc
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Re: C5 x7 2.7 suspension error

Post by Kees »

Sorry Marc,you're right, but even so, the C6 needs also information from the sensors on the strut tube and other info, so i still think he has to replace the BHI from the tourer.
Greetings,
Kees.
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Re: C5 x7 2.7 suspension error

Post by GiveMeABreak »

Yes the 2 suspension ECUs have different functions on V6 engines and you need to remember that the C5 X7 models do not have AMVAR, so the suspension ECUs from the C6 may need configuring or checking which is done with Diagbox. So I would agree it's better to keep the ECUs from your original vehicle.
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Re: C5 x7 2.7 suspension error

Post by Kees »

I know there was someone on this forum, or in the Netherlands, who built everything from a C6 with amvar on a C5 X7, but it was for him not possible to tell the system, that he has ths CCS from a C6 diagbox still recognized it as a C5.
Greetings,
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Re: C5 x7 2.7 suspension error

Post by GiveMeABreak »

I expected as much. :wink:
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Re: C5 x7 2.7 suspension error

Post by chris_reade »

Thanks guys, I think we knew most of that. But the comms error existed with the old pump and BHI, and it's still there now with replacement pump and BHI.

The pump does at least work where the old one didn't.

Still unsure of exact location of the second ecu. Kees, you say it's on the left side where the fuses are? Could you be more specific? Under the bonnet or in the back by the battery?

I think eliminating the comms error is key. Once we've done that the system should activate at least. If it doesn't work as expected we could then replace the original BHI.

Any pictures or circuit diagrams would be much appreciated.

Cheers

Chris
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KennyW
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Re: C5 x7 2.7 suspension error

Post by KennyW »

May I suggest you check the wiring to the diagnostic socket for continuity. Likewise other parts of the system for continuity.

I had a similar problem on my C5x7 and it turned out to be the diagnostic unit itself. I presume your mechanic's Diagbox is fully working and recognising all the ecu's fitted to your vehicle.

Kenny.
C5 x7 2.0 HDi 160 hp Estate exclusive, moved on.
Xantia 2.0 Hdi 90hp 1999 only 189,000 and rising!!!!!!! Moved on to a new home
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Re: C5 x7 2.7 suspension error

Post by GiveMeABreak »

chris_reade wrote: 09 Jul 2024, 15:07 Thanks guys, I think we knew most of that. But the comms error existed with the old pump and BHI, and it's still there now with replacement pump and BHI.

The pump does at least work where the old one didn't.

Still unsure of exact location of the second ecu. Kees, you say it's on the left side where the fuses are? Could you be more specific? Under the bonnet or in the back by the battery?

I think eliminating the comms error is key. Once we've done that the system should activate at least. If it doesn't work as expected we could then replace the original BHI.

Any pictures or circuit diagrams would be much appreciated.

Cheers

Chris
X7 27 CSS Suspension ECU.png
(9) Variable damping suspension (CSS) ECU (dedicated to the power steering and the body height sensor).
(Note: despite name, there is no variable damping (AMVAR), it's just retained the same name from the C6.
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Re: C5 x7 2.7 suspension error

Post by chris_reade »

Thank you for all your help. I'll let you know how we get on. Chris