C5 suspension fault

[Simple76]

Hi have c5 mk1 with serious suspension fault. Pump motor works when feeding signal wire with 12v. Can run motor with diagnostic machine (not Lexia) but only for about 2 seconds. And will run if you turn the ignition on for about 2 seconds . Supply to pump motor is good all fuses good. Any ideas would be greatly appreciated.

[GiveMeABreak]

Hi and welcome - have a look at this post:

viewtopic.php?f=22&t=60565&hilit=suspension

This is for an X7, but similar for the MK I. You'll probably find that there is some oily residue in there and some gunk. Don't operate it too long when it is playing up or you may cause overheating.

[Simple76]

Hi have removed and cleaned motor and bench tested. There doesn’t seem to be a problem with motor . There must be something (possibly bsi) seeing another fault and not letting it run . Have checked supply voltage and signal wire . Problem being supply wire only triggered for couple off seconds.

[GiveMeABreak]

I was going to suggest a Lexia - as you will get far more information than a generic code reader - this may give us some fault codes to work on - an example - if there are any faults in the height correctors then a backup mode will be enabled and that will prevent the pump or height correction.

Are you testing this on the vehicle? If the car battery is in a poor state of charge, it will shut off systems until the engine is started. Like the Economy mode - it seems that it is stopping the pump consistently at 2 seconds....

These are some of the faults that can be read with Lexia:

• Battery voltage low
• Battery voltage high
• Ignition+ input in the suspension ECU is absent
• Hydractive electrovalves 3+ defective
• Front raising electrovalve defective
• Front lowering electrovalve defective
• Rear raising electrovalve defective
• Rear lowering electrovalve defective
• Electropump motor defective
• Steering wheel angle sensor defective
• Absence of communication with the ABS ECU
• Invalid data from the ABS ECU
• Front body height sensor: low ground clearance (open circuit, short circuit to earth)
• Front body height sensor: high ground clearance (short circuit at 12 V)
• Rear body height sensor: low ground clearance (open circuit, short circuit to earth)
• Rear body height sensor: high ground clearance (short circuit at 12 V)
• Invalid data from the front body height sensor
• Invalid data from the rear body height sensor
• Absence of communication with the engine ECU
• Invalid data from the engine ECU
• Absence of communication with the built-in systems interface
• Height push-button defective
• Suspension ECU configuration not carried out
• Suspension ECU defective
• Defective communication on the CAN network

[Simple76]

Ok thanks possibly need to invest in Lexia . Had one before but was cheap and nasty .

[GiveMeABreak]

Check out the Diagnostics section in case you haven't seen it:

viewtopic.php?f=51&t=60112

[white exec]

There was a Lexia for sale here, a couple of days ago...
viewtopic.php?f=7&t=60875#p585365

[Simple76]

Ok thanks . I can get most off the readings up on my scanner electro valves etc .

[EDC5]

Could it be the motor relay module built into the pump motor housing.
I believe it's a solid state switch of some sort so may have failed?

[Simple76]

If I give the relay a feed it works fine. It’s the supply to the feed wire that’s the problem it’s only supplies voltage for a short period ie 2seconds .

[Simple76]

I’m thinking it must see a fault somewhere and it’s not letting the motor. Probably bsi

[GiveMeABreak]

Ok, so I'm just trying to get a feel for the original problem.

So previously you were getting a suspension fault message on the car multifunction display?
Were there any symptoms that youi were aware of apart from the message that affected the suspension?
Were you able to lower and raise the car suspension manually and was car complying / pump working?

Normally, the pump does not operate for more than a few seconds anyway, under normal conditions, maintaining the height through the exhaust electrovalves.

If there is a particular suspension fault, one of the backup modes may be kicking in, which will prevent height correction taking place and limiting suspension to 'Normal' height setting. If it is one of these backup modes, then it won't operate properly until the fault is resolved - which is why a Lexia is really essential to get the specific fault codes, as there are so many possibilities.

If the suspension ECU (which is built into the Hydraulic Block), or data received from the BSI (speed information, steering wheel angle sensor on ESP equipped models), height correction data from the sensors or a CAN fault as examples indicate a problem, then it is DESIGNED to limit functionality for safety reasons.

If you can get Lexia on it and provide us with some codes it really will help with suspect areas - there's just no way to do this properly without a Lexia to be honest.

[Simple76]

Ok thanks original fault was serious suspension fault displayed on display. Vehicle was at its normal ride height but would not let you raise or drop the suspension . Now I have depprusiesd can’t get it to lift even if I run the pump by feeding signal wire with 12v although pump will run as long as I hold supply on .

[GiveMeABreak]

If you fully depressurised the system, it may take some minutes to start rising - if it doesn't, then you may have a faulty electrovalve (s). Do you have the VIN, so I can consult some data?

[Simple76]

Yes it’s VF7**************[VIN obfuscated, can be read by forum staff] thanks again.