StuckAgainSteve

StuckAgainSteve

Well-Known Member
Getting a fault code (pressure switch stuck on) and the EAS is changing height occasionally uncommanded - my gut feeling says EAS driver pack knackered. The compressor seems fine, logging the pressure switch activation, inlet and exhaust values and going for a drive indicates they are actually operating as expected - so the switch is NOT faulty - well, it's not stuck open as the fault code says.
 
There is no direct link between the pressure switch and the driver pack but pressure switch stuck does seem to be associated with driver pack problems. You can try cleaning the connectors in the EAS box, it has worked for me in the past. Also try running with the lid off the EAS box as since I put ventilator holes in the lid I've had no more trouble. It's early days to be sure that it's temperature affecting the driver pack but my forthcoming trip to the UK should test it.
 
Thanks for that Datatek, I will have a poke round at the connectors, although I think I'll chuck a new drive pack at it - it's only £175. I might stick a PC cooling fan on the EAS case to extract hot air from it however the inconsistent ride height is happening from cold.
 
StuckAgainSteve said:
Thanks for that Datatek, I will have a poke round at the connectors, although I think I'll chuck a new drive pack at it - it's only £175. I might stick a PC cooling fan on the EAS case to extract hot air from it however the inconsistent ride height is happening from cold.
Click to expand...

White plug at passenger side or height selector switch.
 
StuckAgainSteve said:
I didn't want to mess around with plugs under the seat incase I set the airbags off - but if you say the white connector is EAS then I'll have a go at that - thanks!
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Not under the seat, behind the trim in the foot well forward of the passenger side front door in the A post.
Forget the fan, just drill some holes on the sloping edge of the lid on the compressor side.
 
Sadly cleaning all the connector made no difference. There's a new drive pack on its way, at least the car's drivable but has the ride quality of a Shogun when the suspension decides to play up. At least it's not faulting and dropping to the bump stops I suppose!
 
Changed the driver pack and the dancing about has stopped - in fact the ride quality feels much better in general - perhaps the driver pack has never been quite right in the time (2-3 years) I've had the car? It just got worse to the point I noticed it? Anyhow - one happy bunny. :D
 
StuckAgainSteve said:
Changed the driver pack and the dancing about has stopped - in fact the ride quality feels much better in general - perhaps the driver pack has never been quite right in the time (2-3 years) I've had the car? It just got worse to the point I noticed it? Anyhow - one happy bunny. :D
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Think you maybe riding on a bout of euphoria, the driver pack just does as it's told by the ECU. No way can it change ride quality. :)
 
wammers said:
Think you maybe riding on a bout of euphoria, the driver pack just does as it's told by the ECU. No way can it change ride quality. :)
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Hmmm, not sure about that Tony, it drives the solenoids using pulses, slow switching transistors or leakage currents could well change the way the valve block responds. Hard to tell how noticable it would be though but could result in a certain amount of instability in pressure in th airbags:)
 
wammers said:
Think you maybe riding on a bout of euphoria, the driver pack just does as it's told by the ECU. No way can it change ride quality. :)
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I suspect if it's opening/not opening solenoids at random the ride quality would be greatly affected. The "spring rate" of the air bags apparently changes greatly with ride height.
 
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StuckAgainSteve said:
I suspect if it's opening/not opening solenoids at random the ride quality would be greatly affected. The "spring rate" of the air bags apparently changes greatly with ride height.
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Ride height is controlled by readings from the height sensors. If the sensor readings are regarded as high or low by the ECU for the given profile you are in, it will raise or lower to suit. If the driver pack does not do as it's told and lift or lower to suit the ECUs requirements, the ECU will shut down and throw a fault. Driver pack does not control ride height the ECU does. Driver pack just opens and closes valves as needed.
 
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I can see what you're saying but disconnect the driver pack (from a fully filed system) and go for a quick spin you'll notice the ride quality is excellent as the four corners sustain a set height (and therefore spring rate) connect the system back up and you'll notice a slight deterioration in ride quality as the system constantly tries to correct a pitching and rolling car. Also the constantly reoccurring "open pressure valve" fault code has gone even thought it's technically nothing to do with the driver pack. Slow or erratic solenoid operation might might do enough to keep the ECU happy but IMHO it must have a detrimental affect on the vehicle dynamics as the system over corrects itself constantly which a sensitive driver may notice.
 
StuckAgainSteve said:
I can see what you're saying but disconnect the driver pack (from a fully filed system) and go for a quick spin you'll notice the ride quality is excellent as the four corners sustain a set height (and therefore spring rate) connect the system back up and you'll notice a slight deterioration in ride quality as the system constantly tries to correct a pitching and rolling car. Also the constantly reoccurring "open pressure valve" fault code has gone even thought it's technically nothing to do with the driver pack. Slow or erratic solenoid operation might might do enough to keep the ECU happy but IMHO it must have a detrimental affect on the vehicle dynamics as the system over corrects itself constantly which a sensitive driver may notice.
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Sorry does not happen, pitching and rolling has no effect on EAS, it is designed to accommodate suspension movement. What if you have suspension fully articulated are you telling me it tries to adjust corners back to level. It just doesn't. The suspension simply cannot react to roll and pitch as you drive. As a matter of fact it's designed not to. You would need to be a very sensitive driver to notice something that does not happen for sure.
 
wammers said:
Think you maybe riding on a bout of euphoria, the driver pack just does as it's told by the ECU. No way can it change ride quality. :)
Click to expand...

That may be technically correct but I changed the driver pack on my 2000 p38 and the ride quality and handling was instantly transformed
 
wammers said:
Sorry does not happen, pitching and rolling has no effect on EAS, it is designed to accommodate suspension movement. What if you have suspension fully articulated are you telling me it tries to adjust corners back to level. It just doesn't. The suspension simply cannot react to roll and pitch as you drive. As a matter of fact it's designed not to. You would need to be a very sensitive driver to notice something that does not happen for sure.
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No P38 I've ever driven (even new ones way back when) feel consistent over bumpy roads, the suspension must be doing some kind of levelling I can log the EAS activity when driving I bet the various solenoids are being opened and closed regularly. The shifting around I can feel stops if you disable the EAS - I feel exactly the same thing driving some Citroens. Surely a worn or breaking down driver pack will make these sensations worse as it takes longer for various corrections to happen? And yes I am very sensitive to the way vehicles react to bumps etc - probably from my motorbike racing days! :D
 
StuckAgainSteve said:
No P38 I've ever driven (even new ones way back when) feel consistent over bumpy roads, the suspension must be doing some kind of levelling I can log the EAS activity when driving I bet the various solenoids are being opened and closed regularly. The shifting around I can feel stops if you disable the EAS - I feel exactly the same thing driving some Citroens. Surely a worn or breaking down driver pack will make these sensations worse as it takes longer for various corrections to happen? And yes I am very sensitive to the way vehicles react to bumps etc - probably from my motorbike racing days! :D
Click to expand...

The suspension once set at standard profile, subject to the vehicles loaded and distributed weight at the time, allows full travel within that profile. NO adjustments are made for undulating roads, roll or pitch. Other than the front axle equalisation as the vehicle speed drops below 1 mph.
 
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