C5 height sensors

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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Thanks Marc and icwin,
No I haven't unclamped the the connection to the anti roll bar, just disconnected the dog bone, I had assumed the 5mm locking pin had to be left in until it was re connected but according to the Haynes manual this is not the case, with the pin removed it's a simple matter to attach the dog bone, the rear one I reconnected with the pin in with no problem.

Before raising the rear to change the height corrector the lds was at the normal level with the car on low, upon lowering it back down the tank filled up presumably because the rear wheels had been off the ground.
Am just going to go unplug all the multi pin connectors in the glovebox and spray with switch cleaner to see if this makes a difference, incidentally is there a relay to switch the pump on?, if it's underneath the ecu next to the engine bay fuses it's sealed to the unit, not good news.
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GiveMeABreak
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Re: C5 height sensors

Post by GiveMeABreak »

The relay for the pump is build onto the BHI (Hydraulic Interface) itself - but if the pump is operating then it's not the relay.

I suggest you try bleeding the system:
  • Apply a pressure of 0.5 bar in the LDS fluid reservoir.
  • Start the engine.
  • Wait for the vehicle height to stabilise.
  • Place the suspension height control in the "HIGH" position.
  • Place the suspension height control in the "LOW" position.
  • Turn the steering from lock to lock in each direction.
  • Stop the engine.
  • Check the LDS fluid level.
As it is already on the lowest setting I presume, you can't raise it to the highest position and then lower it, so you'll have to skip that part.

Continue turning from lock to lock slowly about 5 times. Then check fluid.

Start the engine and out the suspension control to normal - but it can take a few minutes to start raising - but you may need to apply some pressure into the tank to get it started. Some use a bicycle pump and a makeshift cap to introduce a little pressure.

As for the height sensors:
Front Height SensorRear Height Sensor
C5 II Height A.PNG
C5 II Height A.PNG (172.49 KiB) Viewed 327 times
C5 II Height B.PNG
C5 II Height B.PNG (189.76 KiB) Viewed 327 times
Disconnect the connector (1).
Disconnect the rod (2), as "a".
Peg the height sensor at " b" using a 4 mm diameter rod.

Remove:
  • The (3) bolt
  • The height sensor (4)
Refitting

Refit the height sensor ( 4).
N.B. : The positioning of the height sensor on the subframe is done with the aid of the pin " c".
Refit bolt (3), tighten to 0.4 ± 0.1 daN.m.

ESSENTIAL: Remove the setting rod from the height sensor.

Connect the connecting rod ( 2), as "a".
Reconnect the connector (1).
Check the heights of the vehicle.
Disconnect the connector (5).
Disconnect the rod (6), as "d".
Peg the height sensor at " e" using a 4 mm diameter rod.

Remove:
  • The (7) bolt
  • The height sensor (8)
Refit the height sensor ( 8).
Refit bolt (7), tighten to 0.4 ± 0.1 daN.m.

ESSENTIAL: Remove the setting rod from the height sensor.

Connect the connecting rod ( 6), as "d".
Reconnect the connector (5).
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Re: C5 height sensors

Post by Gibbo2286 »

I think the lock pin on the sensor is there to set the arb clamp, different to the earlier cars that required the height to be set by measuring the subframe to floor.

But don't take my word for it, I just can't see any other reason for it being there.
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Re: C5 height sensors

Post by GiveMeABreak »

That measuring procedure still applies on all versions of C5 Gibbo - for fine tuning via Lexia. This locking pin I think is to make sure the height sensor retains its position setting when disconnected form the dog bone.
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Stickyfinger
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Re: C5 height sensors

Post by Stickyfinger »

Just REMEMBER to REMOVE the locking pin before you lower it :)

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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Have just been out and pressurised it with an eezibleed but no difference, with the engine running it's very difficult to hear if the pump is running, it wasn't when the door was opened.
The dash display only shows lowest position, no normal, high, etc

This all seems to point to the BHI or electrovalves but I won't have lexia back until Thursday at the earliest, the previous actuator tests wouldn't raise or lower but I don't want to start taking the pump off unless I have to.
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Re: C5 height sensors

Post by GiveMeABreak »

You should easily be able to hear the motor kicking in - it is quite distinct - if you can't then it is likely it is not kicking in - assuming you've checked the fuses - there is a motor relay - which should be on or near the pump housing. It has a 5 pin grey connector with only 4 wires.

X774: body height sensor supply + (Pin 1)
M774: EARTH M774 (Pin 2)
B7740: battery + (Pin 3)
7740: Left-hand rear body height sensor + power supply (Pin 5)
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Just checked, the only connectors in that vicinity are the multi pin plug to the bhi and the motor cables.
Would the relay only be fitted to mk1 cars?
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Re: C5 height sensors

Post by GiveMeABreak »

No it’s also on the Mk III, but has more connections.

The MK III has A technical service bulletin to say the relay can be replaced if the motor fails to operate with no other fault codes. There’s nothing about the Mk II though, although it should be a similar operation.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Hi Marc,
Looking at the wiring diagram the relay seems to be in the BHI (electronic?) you said earlier:
The relay for the pump is build onto the BHI (Hydraulic Interface) itself - but if the pump is operating then it's not the relay.

When I get lexia back online I'll check again to see if it will actuate the motor, if not then I'll take off the whole unit and strip it down, if it runs it looks like a replacement or remanufacture of the BHI.
Is it possible to open these units to check soldered joints or are they sealed?

Dave
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Re: C5 height sensors

Post by GiveMeABreak »

The ECUs are normally sealed as far as I can tell, and there's no further info about the relay - I've never had any issue with any of mine thankfully, so never needed to go there....yet!

Here's a general video on stripping the pump down:

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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Hi.
Have ordered a used suspension pump/ bhi from Edwards & son, specialist Citroen breakers at Buckwyns near Billericay, it's from an estate of the same year but they think it should be ok as it has the ESP feature, suspect I may have to do a little configuring with the lexia but at £75 plus post I'll risk it.

I also had a word with the local Citroen dealer, Holland motors, very helpful, they are of the opinion BHI problems on C5s are becoming more common as the cars age and the main problem is very few of the ECU diagnosing and repairing companies have the software to work on these units as they are relatively uncommon compared to engine or abs ecu's.
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Re: C5 height sensors

Post by GiveMeABreak »

Yes, they are made by Cinch.

It is essential you have the right BHI for your car as there were different BHIs for the different suspension systems H3, H3+, Estate, Saloon, Engine etc. so if you have the label with the number, put it up here with your VIN and I'll see if lady luck has been good.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Thanks Marc,
BHI should arrive tomorrow, the first two numbers are 96 the same as mine but the others are different, if I can't do anything with the lexia I'll put it on ebay but I'm hoping it will at least raise the suspension and prove the original faulty.

If it's not suitable I suppose we'll be looking at £2-300 for a rebuild of the original, assuming there is anyone to do it.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Hi Marc,
The VIN IS VF7**************[VIN obfuscated, can be read by forum staff]
RPO 10816
My original part no is: 966128510406
The new one is : 965581280