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From time to time, the P38 EAS throws a random fault, for example "Pressure Signal Constantly High".
I have identified one cause of this. An electrolytic fails in the driver pack, this electrolytic is across the power lines and put crudely it stops spikes getting back to the EAS ECU.
It's easy to replace, I've done 3 now and in each case the driver pack and EAS have functioned without recurrence of the fault.
If it's of interest, I could post photo's if I can find out how to and details of the part required.
I mainly post on Landy Zone.
 

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Hello Datatek, long time since I heard from you. Welcome back. Still living in France? Did you finally fit a HP24 gearbox to your diesel? I don't go on Landy Zone anymore. I can't stand the abuse.

Abuse and profanity is nipped in the bud on this forum. It is testament to the excellent job our forum administrator, RRTH, does.

Yes, I would be interested in a write up on how to repair the driver pack. I have got 2 faulty ones in the garage. As a start, how to get the sealant off. I tried several solvents but did not get very far.
 

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Hi Datatek, I too am very interested in this fix! Mine has been throwing the same fault at random for a while now. I clear it and it'll pop up days or weeks later.

I was really hoping the driver pack would be serviceable - I've seen people replace relays on the BeCM power board, and since the driver pack performs a similar function for the valve block, I figured why not? It would be even easier to know it's simply a cap that's gone bad!
Would love pics and a diagram (and p/n for the bad cap) :)
 

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Below is a picture of a repaired driver pack, you can see in the corner a small area where the potting is different. This is the area that has to be dug out, it should be done with a small blunt instrument taking great care not to damage the printed circuit board. You will reveal an axial electrolytic.
Wire Electronics Technology Electronic device Electrical wiring

You can see in the next picture of a board I have completely un potted what the electrolytic looks like You must only dig out just the corner or you risk causing damage.
When you have it clear of the potting, note the polarity of the electrolytic and carefully snip the wires as close to the component as possible and remove it.
The electrolytic is 100uf, 63 volt 105C rating. A higher temperature rating is good if you can get it bot NOT lower. Capacity and voltage are good as they are.
Insert your new component, with correct polarity into the hole and solder to the wires standing up from the printed circuit board, do not use too much heat or the wire may drop out of the board.
Electronics Electronic component Technology Electronic device Auto part
Electrolytic in lower left corner.

When done, seal the hole with electrical grade silicone compound. You may wish to test the pack first, but if you have confidence in your soldering there should be no need.


Good luck, I hope this works for you if you use it. It is not a magic cure, it only applies to the random “Pressure Signal Constantly High” and similar intermittent faults so may not fix your EAS problem, but it's cheap and easy to do, so nothing lost by trying it.
 

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Bookmarked, and will be trying this later this week (with the help of a friend who designs and builds high end audio boards for a living so I'm sure this'll be a piece of cake. :) )

Thanks for sharing! Hope this cures my random Pressure fault... I ran the pump for 10 min - with a two minute cool down every two minutes - and monitored the pressure switch with a multimeter. It did eventually close, so I know it's working. But I still get that fault randomly!
 

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Bookmarked, and will be trying this later this week (with the help of a friend who designs and builds high end audio boards for a living so I'm sure this'll be a piece of cake. :) )

Thanks for sharing! Hope this cures my random Pressure fault... I ran the pump for 10 min - with a two minute cool down every two minutes - and monitored the pressure switch with a multimeter. It did eventually close, so I know it's working. But I still get that fault randomly!
The pressure switch doesn't go through the valve driver though, its got nothing to do with it per se. Sounds like you've already identified the problem...the switch, leave the driver pack alone, they're far more reliable - IMO - than some seems to think.

The code I think your referring to is due to (LR quote) "...when air usage does not correspond to the implied air pressure..." which it doesn't directly know, but if the switch is giving the wrong readings, seems reasonable that this code would result.
 

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The pressure switch doesn't go through the valve driver though, its got nothing to do with it per se. Sounds like you've already identified the problem...the switch, leave the driver pack alone, they're far more reliable - IMO - than some seems to think.

The code I think your referring to is due to (LR quote) "...when air usage does not correspond to the implied air pressure..." which it doesn't directly know, but if the switch is giving the wrong readings, seems reasonable that this code would result.
Are you sure the pressure switch doesn't route through the driver? When I was researching it before a lot of LR forum posts around the internet pointed to a driver replacement as the only surefire fix, and that the sensor rarely goes bad. I tested it and the switch did close after running the pump so it's opening and closing in response to pressure changes in the tank. If it was indeed stuck closed i'd have gotten consistent continuity in that circuit.

According to the OP the capacitor repair directly affects the "Pressure constantly high" error code. Electrolytic cap's usually only last ~10 years, especially in a high heat environment. Let's hope it's right!
 

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Are you sure the pressure switch doesn't route through the driver? When I was researching it before a lot of LR forum posts around the internet pointed to a driver replacement as the only surefire fix, and that the sensor rarely goes bad. I tested it and the switch did close after running the pump so it's opening and closing in response to pressure changes in the tank. If it was indeed stuck closed i'd have gotten consistent continuity in that circuit.

According to the OP the capacitor repair directly affects the "Pressure constantly high" error code. Electrolytic cap's usually only last ~10 years, especially in a high heat environment. Let's hope it's right!
Well, thats some forums, and some posts for you. Shame you don't look at whats in-front of you, got to prove it I guess.

Electronics Technology Electronic device Auto part Electronic component


Pressure switch wiring is direct (via plugs) to the EAS ecu.

The EAS ecu only has so many inputs with which is make decisions on any potential problems and therefore can get it wrong if its not a specific type error, like height sensor errors (in my experience).

The OP's fix would have to be explained as to what it does and what its actually trying to achieve to comment further, at the moment it's just vague, just like the code it's trying to fix.

My driver pack is original and now 20 years old.
 

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Pressure switch wiring is direct (via plugs) to the EAS ecu.

The EAS ecu only has so many inputs with which is make decisions on any potential problems and therefore can get it wrong if its not a specific type error, like height sensor errors (in my experience).

The OP's fix would have to be explained as to what it does and what its actually trying to achieve to comment further, at the moment it's just vague, just like the code it's trying to fix.

My driver pack is original and now 20 years old.
Ah, yeah thanks for the pictures, I haven't had the valve block out yet so haven't inspected myself. I would imagine the driver pack itself is very reliable, being MOSFET's not Relays (á la BeCM). But I do believe what the OP is saying about the electrolytic going bad. They're not known for their longevity, either leaking or having the fluid inside drying out.
And if it's there to absorb and buffer any power spikes, I can see how the EAS ECU would be unable to understand and start throwing random codes.
Since Datatek keeps saying it fixes the random "Pressure signal constantly high" code that I've been experiencing, and I know the pressure switch is indeed closing properly, I can only hope that a dry/leaky cap is to blame and causing the ECU (which isn't exactly the smartest piece of kit...) to go a little crazy.
 

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I'm not going to dispute that electrolytics do fail (I've replaced enough in just about every form of electronics over the years) but the suggested cure does seem a bit drastic. The danger of damaging something else while digging the potting out, is very real even though the generally accepted way is to use freezer spray on it to make it brittle so it cracks away easier. However, if the electrolytic is across the supply, why not just fit it externally to the potting? The failed one will be losing it's capacity and another in parallel will add to the value. If it is simply for smoothing, then a lower value won't do the job but a higher value won't do any harm at all.
 

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Hi All, been having this EAS fault Pressure sensor high and going on high ride height and beeping at me all the time FAULT.
So thank goodness for this thread.
I have done this work today. Let’s hope it works 😉.
See pics,
cheers,
Paul.
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Having recently acquired a batch of valve blocks from a company that used to do coil conversions, I've been testing the driver packs by putting 12V on the input pins for each solenoid and checking that every output works. What I've found on a couple of them is that only one output has failed, the others all work fine. That would suggest a fault on an individual channel rather than the driver pack itself. If that is the case, I can't see changing a cap across the power will make any difference at all.
 

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I have two driver packs where the input wires are intermittent. All outputs work, but some of the solenoids only trigger when wriggling the input wires. These both cause "Valve Stuck Closed" & "Valve Stuck Open" faults, even though the real problem is intermittent wiring !!

Really annoying, because the only fix is to get the PCB out and re-solder. I have picked out most of the compound, but simply cannot lift the PCB from the metal housing.

Would be really nice to find a suitable solvent, even if only to soften the compound a bit.
 

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I have tried a few solvents with no effect ... acetone, isopropyl alcohol, methylated spirits, white spirit and petrol. It is probably some sort of epoxy, which is pretty inert to solvents.
 
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