P38 EAS random problems

[Boblofty]

Looking for some help guys. 2001 P38 AES. Just out of the blue it has started doing the weirdest things. Sometimes when the engine is shut off it will chase it's tail trying to self level until it is on the stops. Sometimes it wont.
Some mornings it will be down completely on the right hand side....sometimes it wont. Other mornings it will be down at the back...sometimes it is not.
On just the odd occasion it will be perfect and act as it is supposed to and performs perfectly on the road in all aspects.
What have I done so far.
I have replaced the computer.
Rebuilt the valve block (twice)
Eliminated all and any leaks.
Rebuilt the compressor.
Changed the sensors side to side back and front.

The weirdest thing of all is that it will run happily out of shape (in any configuration) until it 'alarms' out (which it doesn't do all the time) it will then reset with the 'kicker' and act normally for maybe a day or a week and then back to its random faults.
About the only things I haven't done are replace the self level relay or the valveblock driver.
Self level will be replaced as soon as I can get one delivered. I have Story Wilsons software but it is either corrupt or my laptop is so I can't access the AES computer to fault find or make any changes.

Now my knowledge of the system is pretty good and my engineering skills are very good but this has me stuffed.....it is looking like repair by replacement until I get it right.



Any suggestions would be appreciated, I have run out of hair.

[finallyrangie]

You could try replacing the timer relay with a standard yellow one, that should stop the computer getting involved overnight, might give you an idea if it's electrical or a more physical air problem, you might want to try downloading the eas software again, you might get lucky.

Good luck and keep us posted

[TheTree]

Hi

Check the OBD connector they are known to get a bit of corrosion in them. Clean it up and you will most likely be able to connect.

Secondly pull the EAS relay at night and see how it behaves, if it is OK then the problem is most likely the valve block driver

Steve

[Boblofty]

You could try replacing the timer relay with a standard yellow one, that should stop the computer getting involved overnight, might give you an idea if it's electrical or a more physical air problem, you might want to try downloading the eas software again, you might get lucky.

Good luck and keep us posted

Thanks' finallyrangie. That will be tonight's exercise. Just finished the valveblock rebuild late yesterday and left the vehicle stand with a full tank of air and measurements at the corners. Cold evenings here in Canberra but the losses after 3 hours were about 1/2cm at all corners and bugger all from the tank. Hoped I had solved the matter but thismorning it was down at the back and although it came up to height quickly, after golf it was back down again and although it came back up on the way home, as soon as the engine was turned off it settled to the stops chasing a level. arghhhh.
That (I hope) can only be the relay waking up after 5 hours in the dark and the whole system getting out of wack after that.
This is definitely an exercise in self control and leave the matches locked away.
I will get this solved. Cheers

[Boblofty]

Thanks' finallyrangie. That will be tonight's exercise. Just finished the valveblock rebuild late yesterday and left the vehicle stand with a full tank of air and measurements at the corners. Cold evenings here in Canberra but the losses after 3 hours were about 1/2cm at all corners and bugger all from the tank. Hoped I had solved the matter but thismorning it was down at the back and although it came up to height quickly, after golf it was back down again and although it came back up on the way home, as soon as the engine was turned off it settled to the stops chasing a level. arghhhh.
That (I hope) can only be the relay waking up after 5 hours in the dark and the whole system getting out of wack after that.
This is definitely an exercise in self control and leave the matches locked away.
I will get this solved. Cheers

Yeh thanks Steve. I considered that but the fact that the kicker works every time made me discount that as a possibility. However in the words of the immortal Khan...never assume anything. I will check

[TheTree]

If the kicker works every time I would be looking at the earth points around the EAS system and thinking the valve block driver may be dodgy. Does the epoxy in the driver look OK or is it crumbly ?

Steve

[Boblofty]

If the kicker works every time I would be looking at the earth points around the EAS system and thinking the valve block driver may be dodgy. Does the epoxy in the driver look OK or is it crumbly ?

Steve

Steve. You have inspired a new way to look at this problem. There is a common point to all of the system and that is the OBD port...if as you suggest there is corrosion and this is causing an intermittent earth, this could (possibly) trigger one or more of the suspension bag relays (or others for that matter) to operate in a random fashion.
I went out briefly tonight and after driving for some time with the right side down, I stopped briefly and when I started off again the bloody thing came up square and by the time I got home *about 10 mins) it was behaving itself.
In preparation for the electrics off test tonight, I replaced the standard relay with a 4 pin yellow and was standing by the gauge waiting for the tank to top up (I have fitted up a charge point and pressure gauge) and I noticed that the compressor seemed not to be charging the tank. It has just been rebuilt and so I pulled the silencer to check suction and it was sucking and therefore pumping so the air had to be going somewhere.
Turned the engine off to see if I could hear air escaping and one (and I don't know which one) of the relays went off clicking like mad (power should be off remember) and then stopped.
Obviously something is capable of feeding power to the valve block despite the system supposedly being electrically isolated.
In answer to your comment regarding earth points around the system, impossible to check everything of course but it is fair to say that the back of the drive looks like it has been mildly cooked or is just a dirty brown colour.
I have been a 'sparkey" for over 40 years and it doesn't smell cooked, just looks it.
Tomorrow I shall check the OBD for corrosion and seriously consider both a driver and relay second hand from Adelaide.
Thanks for all your responses thus far.
Cheers Bob

[daf11e]

Bob I have a spare driver here in Sydney if you'd like I can post it to you to try before you commit to buy.........just send me a PM


Jim

[Keithy P38]

I am helping an elderly gent up here in Townsville with the exact same issue you are having - to the word.

The only thing we haven't done is replace the driver unit or put it on coils. We've checked earths, checked for leaky air lines, replaced the valve block, replaced all air springs with new, traced wiring looms, etc. I've made an emergency bypass kit for him so he can set the P38 at his desired height and remove the delay relay to stop it moving in the event it plays up. It's a temporary fix, but allows him to pump up at the servo or using his own compressor if the gremlins creep in.

I cannot connect to his EAS ECU with my nanocom, but he has a kicker and Faultmate FCR that both communicate with the EAS ECU with no dramas.

His OBDII port is clean and corrosion free.

I will:

a) Follow this thread with much interest, and
b) Reply back with findings if we discover the problem.

As I said before, his P38 has the EXACT same issue you have. It's a '98 HSE.

Cheers for posting!
Keithy

[TheTree]

Hi

Apart from the under bonnet earths, which you would think are OK since the compressor runs, there is also the earth under the passenger seat.

Might be worth checking

Steve