P38 spontaneous rise to extended height

I had this in my previous P38 as well, how about you guys? I drive along in town at slow speed, and suddenly the suspension rises to extended height. What is going on?

Driver pack?

Or a height sensor giving dodgy readings. Had the same on mine, it eventually went down with the dreaded 35mph message. It was the front right height sensor. I posted pictures of the sensor internals a while back.

Datatek said:

Or a height sensor giving dodgy readings. Had the same on mine, it eventually went down not with the dreaded 35mph message. It was the front right height sensor. I posted pictures of the sensor internals a while back.

Click to expand...

Agreed, mine does this now and again i do know the N/S front sensor does not like damp conditions. Will get around to changing it before winter arrives. The driver pack can't do anything unless the ECU tells it to.

wammers said:

Agreed, mine does this now and again i do know the N/S front sensor does not like damp conditions. Will get around to changing it before winter arrives. The driver pack can't do anything unless the ECU tells it to.

Click to expand...

Me mates was frequently shooting up to high mode then few minutes later eas fault until reset... he changed the driver pack and it aint done it since... im no eggspurt but thats wot append

do the simple thing first. The air suspension unit has an exhaust passenger end of the plastic pipe outlets. If its blocked it will think there is something fouling the bottom so will extend the height., Changed alsorts on mine and it all came down to a blocked exhaust. Believe or not these are £22. Unscrew it and see what happens. Will sound like a truck brakes when it exhausts but give this a go first. could save a lot of time and expense. I put a small hole in it and works fine now

nathan5346 said:

Me mates was frequently shooting up to high mode then few minutes later eas fault until reset... he changed the driver pack and it aint done it since... im no eggspurt but thats wot append

Click to expand...

Fair enough. Mine occasionally goes to high, i press the button and it goes to normal setting. As i said the N/S front sensor is a little dicky giving faulse readings now and again. I would think any failure within the driver pack would result in a solid fault. The driver pack is a switching unit for the ECU which cannot handle the voltages required to operate the selonoids. If it is solid state, as i think it is, a power transistor either works or it does'nt there is no inbetween as i understand it.

Thats what i like about l/z a great source of information

Same problem I had too. New driver pack and all sorted. I do get a drop in height over night, but I think the airbags are knackered and need replacing soon.

Anyone know common places for airleaks in the system ?

wammers said:

ECU which cannot handle the voltages required to operate the selonoids. If it is solid state, as i think it is, a power transistor either works or it does'nt there is no inbetween as i understand it.

Click to expand...

Unfortunately, power transistors can do strange things. Leakage currents can change, they can turn on and fail to turn off, heat can cause unwanted conduction, the list goes on............. But you are exactly right about the fact that the driver pack is the interface that allows logic level signals from the EAS ECU to activate the solenoids. Ought to be fairly easy to design a replacement if the Driver Pack becomes hard to get. It has the same function as part of the air control system I designed.

Thank you all for the advice. I followed the majority rule and assumed it's the sensors. Swapped left for right with no difference. Next is the driver pack? Incidentally, the car goes to extended rather than high profile: top light flashing after settling down.

dannys said:

Thank you all for the advice. I followed the majority rule and assumed it's the sensors. Swapped left for right with no difference. Next is the driver pack? Incidentally, the car goes to extended rather than high profile: top light flashing after settling down.

Click to expand...

You are still using the same sensors so the fault may still be one of the sensors or connectors/wiring.The vehicle goes to extended height when it tries to lower one or more corners and after a period of time does not detect a height change from one or more of the sensors.The EAS ecu then persumes the chassis is grounded and sets all four corners to the extended height.I think it remains in that mode for ten minutes before in reverts to normal height.

I thoght the sensors were handed?

dannys said:

Thank you all for the advice. I followed the majority rule and assumed it's the sensors. Swapped left for right with no difference. Next is the driver pack? Incidentally, the car goes to extended rather than high profile: top light flashing after settling down.

Click to expand...

If the sensor is shot, no point swapping from side to side as virtually the same piece of track will be used. See the photos I posted under Useless Information.