Hydro active suspension problem *Solved*

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dannysconnect
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Joined: 27 Jun 2020, 00:23
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Hydro active suspension problem *Solved*

Unread post by dannysconnect »

Hi All

I am sure this has been covered previously but after looking through old posts I could not find exactly the same issue I am having

I'm an Auto electrician but with limited knowledge of Citroens

A garage called me today to look at their customers 2009 C5 Mk3

It has a problem with the suspension system both front & rear have lowered completely

when toggling the ride height on the switch by the gearstick the car does not raise or lower but the display screen shows height selection followed by a in progress message. it also displays when you switch from normal to sport

no suspension fault warning message on dask

1. The motor/pump does not sound or operate when toggling switches
2. when using launch to activate the pump it says that the activation is occurring but no actual activation of the pump can be heard
3. Only 1 fault code displayed in the suspension control module( U2005) something about vehicle speed not received - although live data shows wheel speed when moving

I checked the ride height correction values also & confused me a little

when jacking the rear of the car the rear height sensor value changes quite rapidly whereas when you jack the front of the car the front height sensor value change is minimal (eg value is at 30 steps when on ground and reads about 36 steps when jacked up (front only)

if the ride height sensors were seized, stuck or out of position would it cause the system to shut down & not raise or lower the vehicle

furthermore would a stuck sensor cause a fault code?

if you require any more info please don't hesitate to ask

I am really trying to understand how this system operates in order to know how to diagnose it step by step
Last edited by dannysconnect on 29 Jun 2020, 22:38, edited 1 time in total.

Gibbo2286
Donor 2020
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Re: Hydro active suspension problem

Unread post by Gibbo2286 »

When you click the remote to open the doors does the pump run, you should be able to hear it?

If not then you need to check it is getting voltage to the pump, I do this by trimming back the insulation on the loom near the pump find the three wires to the pump, two heavy and one light, they are the positive the ground and the signal wires, check that you have power on the heavy wires, I use a sewing needle pushed into each and a voltmeter.

The loom can be found behind the RH headlamp in the corner under the bonnet.

If you have 12v there then the pump is likely the problem, if not then you need to look for the master fuse under the fuse board under the bonnet which if blown is often the first sign of a failing pump.

There's plenty about the pumps in these threads.

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EDC5
Donor 2020
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Re: Hydro active suspension problem

Unread post by EDC5 »

Not all pumps blow the fuse due to the following problem, but carbon build up is one of the main causes:
EDC5 wrote:
22 Jun 2020, 20:58
It is possible that your pump has become contaminated with oil and is causing excessive current to be drawn.

This happened to me and I've got details in these threads here:

viewtopic.php?p=579189

And my repair:

viewtopic.php?p=581404

dannysconnect
Posts: 3
Joined: 27 Jun 2020, 00:23
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Re: Hydro active suspension problem

Unread post by dannysconnect »

thank you so much for your help gibbo

very informative


It does not make a sound when you open the door


I will go on Monday morning and check for power at the thick connector


i am assuming the skinny wire comes from the BSI?

EDC5 - I believe the pump has been changed - I just couldn't find the connector for the [ump to check for power

this is a 59 plate - is the main fuse for the pump in the engine bay on these models?

dannysconnect
Posts: 3
Joined: 27 Jun 2020, 00:23
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Re: Hydro active suspension problem *Solved*

Unread post by dannysconnect »

Got to the bottom of the issue

It was a blown fusible link for the suspension

But it is in a different location on the MK3 (2010)

the fusible link for the suspension pump motor is on a busbar which is attached to the side of the battery tray

It is a green 40 amp fuse link & it is the main feed to the brown relay for the suspension

The relay is located is directly next to the Pump Motor

My guess is the previous pump motor was failing & pulling too much current

After replacing the fuse & measuring its amp draw using a scope the replacement motor draws about 19 amps during is operation with an in rush current of about 21 Amps that stabilises after 20 ms

thanks again for your help guys - It's people like you that make these forums successful

until the next time

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EDC5
Donor 2020
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Re: Hydro active suspension problem *Solved*

Unread post by EDC5 »

That's excellent news, and interesting to have a current reading for a properly oeprating pump.

When mine first blew the fuse, I replaced it with a 50A one and it still blew that! After I cleaned the carbon dust off the brush holder it has been fine ever since.