P38 EAS issue

[daveturnbull]

So after 2 years of ownership, the air suspension on my P38 has died.

Current status is the air spings are all down, the lights on the up/down button are doing as expected, there are no messages on the dash, no fault lights, but the pump is not running.

Things I've checked:

• There is power at the fuse.
• I swapped the relay for another, no change.
• At the pump, I have continuity between orange and black, so thermal cut out is fine.
• If I put 12v direct to the pump it runs. Doesn't seem quite as 'vibrant' as I think it should, but it still runs fine.
• I have continuity at the smaller green / black on separate plug (I think this is for the pressure switch)

I then left the car running with the pump hard wired and a screwdriver handle jammed between a tyre and arch to see if it would start to lift. 10 mins later it's not moved a dot.

So to sum up, no apparent faults, but the pump is not running.

Any thoughts on what I should check next?

[MikeAK]

Hi,

You could try looking at http://www.rswsolutions.com/index.php?option=com_content&view=article&id=53&Itemid=56 free diagnostic sofware for EAS. The download also has pdf of instuctions to make diagnostic cable.

I've used it several times to diagnose both classics and p38s. You get proper fault information, much easier than guessing at what the ecu is unhappy with. It also clears the fault codes and resets the system.

[pete3000]

do you have any air pressure in the tank or at the pressure switch?

[daveturnbull]

How do I check for air pressure?

[pete3000]

http://www.nigelhewitt.co.uk/stuff/eas/pinout.html

use a spider wire linkage to connect pin 1 +12v timed to pin 26 inlet (inflate) solenoid and select a corner eg pin 10 front left or 11 rear left, 27 front right or 28 rear right swap pin 9 for pin 26 to deflate instead of inflate, i.e join 1 to 10,11,27 and 28 to open all corners then pin 26 to inflate. to deflate all, connect pin 1 to 10,11,27 and 28 and 26

pin 13 is pressure switch voltage.

to check compressor will run connect pin 1 to pin 8 (bypasses pressure switch caution)

connect pin 8 to pin 1 to run compressor, 2 mins power at pin 1 once becm is awake, re awaken by open/close door.

all done with ecu harness connector disconnected under passenger seat.

[Escape]

Short term solution would be to use a mains compressor to fill the air tank, simply connect to the upper pipe of the dryer and fill to 7-8bar.

With that pipe disconnect, also run the EAS compressor with pigtails and check for pressure and flow coming out of the dryer.

If you don't get pressure at the dryer, take the exhaust out of the valve block and check for air escaping through there with the EAS compressor running. A faulty diaphragm valve wil vent all/most of the pressure the EAS compressor is building before it gets to the tank. The valve is operated from the same feed as the compressor.

When testing the wiring on the compressor, the thin wire (O I think) needs to be grounded (i.e. connect to the thick B wire) if the thermal switch is closed.

Rest assured, your EAS has not died, it is merely a bit ill. ;-)

Filip

[P38 Paul]

I bought spare a pump off e-bay once & upon fitting to the car found it would not run , fitted the old pump back on & that run ok , hard wired the new pump & it ran ok , fitted it back on the car & still wouldn't run , I recon that your pump has gained the same fault as my spare pump had & I never found out what the problem was , the only way of proving it is to fit another pump . Good luck .

[Escape]

I bought spare a pump off e-bay once & upon fitting to the car found it would not run , fitted the old pump back on & that run ok , hard wired the new pump & it ran ok , fitted it back on the car & still wouldn't run , I recon that your pump has gained the same fault as my spare pump had & I never found out what the problem was , the only way of proving it is to fit another pump . Good luck .

If the EAS compressor runs when hardwired, but not when triggered by the ECU, it's usually a problem with the thermal cutout. Easy enough to check and replace.

[daveturnbull]

Not had much chance to do any in-depth manual wire shorting, but did get half an hour on it today.

I had a spare time delay relay form a friend, so replaced that (after a fight with the stupid fir tree trim clips, now deceased). No change.

I took the pump right off and shoved 12v up its contacts. I could easily stop the little air it was producing with my thumb. Guessing this means it's not well?

With my proper compressor, I fired a good amount of air into the blue pipe (with engine running and pump electrics connected). Didn't raise at all. When I turned the engine off, the exhaust valve did release a few 'shots' of air back through the blue pipe.

Next move I'm thinking I'll have to buy one of those diagnostic cables for £20ish off eBay and use the freeware to read and reset any faults. I now have the MAX 35MPH message on the dash, so it has at least registered a fault now.

[Escape]

Re-read my earlier post, if you want to use a separate (proper) compressor to fill the air tank, you have to connect it to the upper pipe of the dryer, not to the blue pipe of the compressor because it wont reach the air tank unless the diaphragm valve is also powered. If the EAS isn't powering the EAS compressor, usually because of a faulty thermal cutout, it wont power the diaphragm valve either. You could bypass the compressor relay, but much easier to use the pipe from the dryer, it's just a push-fit and easy to reach.

If you can stop the flow from the compressor without much force, it does need a rebuild wit new seals. If you also check (and fix if necessary) the thermal cutout, you should be good to go again.

Not had much chance to do any in-depth manual wire shorting, but did get half an hour on it today.

I had a spare time delay relay form a friend, so replaced that (after a fight with the stupid fir tree trim clips, now deceased). No change.

I took the pump right off and shoved 12v up its contacts. I could easily stop the little air it was producing with my thumb. Guessing this means it's not well?

With my proper compressor, I fired a good amount of air into the blue pipe (with engine running and pump electrics connected). Didn't raise at all. When I turned the engine off, the exhaust valve did release a few 'shots' of air back through the blue pipe.

Next move I'm thinking I'll have to buy one of those diagnostic cables for £20ish off eBay and use the freeware to read and reset any faults. I now have the MAX 35MPH message on the dash, so it has at least registered a fault now.

[daveturnbull]

Ah, right - didn't realise the blue pipe would be the wrong side of a valve. I'll whip the pipe off the dryer and shove some air in there instead when I get a chance.

On the pump I have continuity from orange to black, so the thermal cutout should be ok.

From reading around, it seems like at the very least I need a new pump and a cable so I can reset the fault to kick it back into action again. I guess with the diagnostic kit and the ability to read faults I might uncover more issues.

[daveturnbull]

Popped over to visit my local LR specialist at lunch today, had a good rummage through his 'stock' of bits and came up with a few arm fulls of EAS pumps in various states. Spent a few mins testing them on the bench with a jump pack and found one that seemed to have a fairly sensible output, so took that away to give it a try.

Just been out and fitted it to the car, and success! It ran straight away. Very slowly everything started to creep back up to normal ride height. I even went for a celebratory drive round the block. Almost forgotten how lovely air suspension is.

I've left it with the time delay relay removed to see if any particular corner sinks overnight - just incase a leak may have contributed to the original pumps demise.

So why did my original pump refuse to run when I had continuity across the orange / black? New pump has continuity too. Could the thermal cutout have failed in such a way that it still has continuity until under load? Very odd...

[elbekko]

Maybe it was running but you just didn't notice because the seals were *that* bad?

[Escape]

Glad you got it sorted out! The thermal cutout shouldn't see any real current passing through it, so unlikely to fail under load. If you take of the end of the compressor, the cutout is clearly visible, would be worth a look!

Good thinking on checking for leaks. If it went up fairly straight away, everything is probably in good shape, but better to be sure

Instead of removing the timer, you can also take out fuse 44 (less hassle). Or modify the wiring to prevent self-levelling when the ignition is off (recent topic on here).

Filip

[daveturnbull]

The saga continues...

So this morning, with the relay having been removed overnight, the only corner that looked like it hadn't sunk was the off side front.

I braved the drive into work (20 mins), popped the bonnet when I arrived to find a rather warm pump. I also noticed when I was parking that it was constantly adjusting, by some reasonably large amounts, and as soon as I stuck it in park it pretty much went right up to high (but the light on the switch didn't)

Time for a new valve block and driver unit too?

[Escape]

Hmm, it does look like you have leaks. Spray some soapy water on the connections to the valve block, could be as simple as that.

Any leaks in the system can and will cause strange behavior as the EAS tries to compensate. So it's best to try and sort those out first, before digging deeper.

FYI, the valveblocks can be rebuilt with new O-rings, no need to get a new one. Internal leaks (between solenoids or across NRV) can cause the car to rise without reason, so it could be the valve block. With the timer unplugged, the driver unit isn't powered, so that can't account for dropping overnight.

[daveturnbull]

It's been a while, time for a bit of an update on this.

I managed to borrow a spare valve block and drive pack for testing purposes from my local friendly specialist.

I went round the car spraying every joint, union, connection and all 4 air springs with soapy water, then got it moving up and down whilst checking for leaks. Nothing. Not a single bubble. Oh well, might be a leak inside the valve block, lets fit the spare one. 20 mins later, try the same test again. Bubbles everywhere. Valve block looks like it's got rabies. Bugger. Ok, lets put the borrowed drive pack on my valve block. 30 minutes later, same test. Now my valve block is leaking a little at the air lines, must have been because it got disturbed. Fingers gettting cold so retreat inside to warm up and order a valve block o-ring kit.

Few days later, O-ring kit turns up. Valve block removed from car and installed on kitchen table (much to wife's disgust). Over a couple of evenings, all gets rebuilt with the new o-rings and diaphragm. Not too tricky to do at all.

Popped out last night to fit it all back on the car. I think the local football team had a game on the telly, and judging by the screams of excitement and enthusiastic swearing coming from my neighbours front room they were doing fairly well. (Not a footballist personally, couldn't care less about it). Quickly connected everything back up, fired up the ol' 6 cyl diesel and left it ticking over for a while as the pump does it's thing. Right next to neighbours window. Do I feel bad? No. benefit scroungers with not so much as a part time job between them and 5 sky tv boxes. A few minutes later, all is looking good. Car has risen back up to where it should be, no bubbles at valve block, tank is full, pump has stopped and I can no longer hear any swearing. Maybe the diesel fumes have got them. Turned engine off, shut the bonnet and went inside for a celebratory cuppa.

Drove 20 mins into work this morning, and all appears ok. Pump was warm to touch when I got in, but have been told that they do tend to run fairly warm. Considering cutting a hole in the cover and rigging up an old 12v PC fan.

[Kev66]

Have 1996 range rover p38 dse diesel  automatic. Went to go out and no gears just message 35mph come up engine starts fine  and running on springs not air so any help would be grateful 

[Escape]

Kev, not exactly the right place for this question, maybe an admin can move it?;

The 35mph message is because someone castrated the EAS and replaced it with coil springs (and didn't even do a proper job...). But nothing to worry about if on springs.

No drive could be transfer box in neutral. Check fuse 11 under the seat, it should be empty and is only used to put the transfer box in neutral when being towed. If it's the transfer box, you should be able to push the car even with the transmission in P.

Other possibility is the gearbox itself. Check fluid level (with engine running) and go through all the gears to see if any work. Often when 'D' fails, you can still drive off in '1' and shift up from there.

Filip