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Joined: Apr 10 2018
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Had a few weird issues with the car today inasmuch as the height went to max and eventually onto the bump stops. The 4 neon height indication now has all lights lit, warning on the dash about not exceeding 35mph and no sign of the EAS compressor kicking in.
I have checked the appropriate fuses and relay - they are fine.
I don't know where the thermal switch is, so could do with some guidance on that.
Tailgate is closed so that ain't the culprit.
Should I bridge out the EAS relay load connections to see if the compressor runs or is there something else I should look at first ?
Pleased I kept the Freelander as a spare...lol !
P38 - 2001

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You need diagnostics, either a Nano or similar or the free RSW software and lead (like this https://www.ebay.co.uk/itm/Fits-RANGE-ROVER-P38a-EAS-AIR-SUSPENSION-FAULT-CODE-RESET-DIAGNOSTIC-PC/122111172488). Going up to high signifies a soft fault (which would have cleared if you had switched off and restarted), dropping to the floor shows it has hard faulted and has to be reset.

Without knowing why it has shut down you won't be able to faultfind it. If the system detects a fault it shuts down to protect itself but you need to identify the fault. The thermal switch is in the back of the compressor, unplug it and check for continuity between the orange and black wires although I very much doubt that is the fault. The thermal switch only kicks in if the compressor overheats which it won't do unless you have another fault, either a worn out compressor or leak. It is supposed to reset when it cools down but they tend to saty open circuit is they have operated lots of times. Even if you jump the compressor to build pressure, the ECU has gone into fault mode so won't try to do anything until reset. Did you have any other warning signs? Dropping to the bumpstops overnight or taking a long time to rise up to normal?

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Joined: Apr 10 2018
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Thanks Gilbert, there were no other signs of misbehaviour from the EAS.
I found some YouTube info on the thermal switch - but thanks anyway.
Looks like I'll buy the re-boot software if I can't suss it out.
Next job is to get the trusty Freelander an MOT...
Getting too old for hassle with cars -being 70 I should drive a small reliable Toyota..................who said bus pass ?

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What the software can do is here http://www.rswsolutions.com/index.php/p38a-eas-unlock-videos. Despite being free it is actually very good and if your EAS system has gone into hard fault, you need to be able to reset it before it will start to work again. If you've got no leaks, then the most likely cause of a problem is an iffy height sensor, but you still need to identify which one.

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Joined: Apr 10 2018
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Thanks again Gilbert for the software info.
I tried to jumper the compressor via the EAS relay over-ride - but no joy, I'm now thinking of appyling 12v to the compressor green + and black - to see if it kicks in to life.
I was also thinking the delay relay has thrown a wobbler, but I'm probably clutching at straws and the software is the way to go, as per your advice.
On the bright side the Freelander passed muster with a minor advisory so I have transport ( and a bus pass for back up )

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If no joy with 12V on the green wire and ground on the black, the compressor has died. If it runs but not by jumpering in place of the relay, then check Maxi fuse 2 if a pre 99 car (GEMS) or fuse 40 is 99 or later (Thor).

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If MF2 or F40 have blown, the engine won't crank either, as they power the starter solenoid via a relay in the fusebox.

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Joined: Apr 10 2018
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Got the compressor to run by applying 12v to the required wire and ground to the black wire - also had continuity on the thermal switch, so that's a few quid saved.
By-passed the relay and got a neutral (ground) at the compressor but it didn't run, engine running no open doors or tailgate at time of test
All fuses are OK
From what I gather the relay switches a ground to the compressor, I suspect the 12v is from the EAS module but I really don't know the sequence of how that is achieved.
If a height sensor has gone AWOL and is replaced / repaired,will the software set the ride heights to the factory default positions ?

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You don't need to have the engine running or even the ignition switched on. No, the relay doesn't switch a ground, the ground is there permanently on the black wire to the compressor. Power comes from one or other of the fuses and arrives at pin 3 on the relay (Relay 20), pin 2 has a permanent ground on it so a 12V supply from the ECU on pin 1 of the relay pulls it in and the power on pin 3 then goes out from pin 5 to the green wire on the compressor.making it run. So if you jumper pins 3 to 5, it will run unless it is dead. If it gets too hot, the thermal fuse opens which removes a ground to the ECU telling it that the compresor has overheated so it no longer energises the relay. If you have continuity between orange and black and the relay isn't being energised by the ECU, it is something else that has caused the ECU to inhibit any activity.

This is where you need to put the jumper

enter image description here

The ride heights are set according to the readings given by each height sensor. If you replace one then the chances of the reading being identical to the one you've taken off are pretty remote. It'll be similar but not the same. You need the software to be able to read and write the heights. I changed one of mine recently so before removing it checked the reading it was giving for the height that corner was sitting at which, in my case, was 130. With a jack under the body as well as the one under the axle so the two remained the same distance from each other, I then fitted the new sensor and checked the reading from that. This one was showing 135, so I added 5 to the stored settings on each height for that corner and wrote the new settings into the ECU. If I hadn't done that, it would have sat with that one corner permanently lower than the other three. Ideally it should be calibrated with a set of blocks but I know I've seen them somewhere since moving house but I'm buggered if I could find them. It's sitting level at all heights so it isn't far out but could do with being done properly when I find the blocks.

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Joined: Apr 10 2018
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Thanks for the invaluable info, I jumpered the correct terminals as per your pics and the compressor ran OK.
Is it the case that because of the "Hard Fault" the bags won't inflate even though the compressor is running and the software reset needs to be done to allow inflation.

Drove down to the shops to get some bread when the car was on the bump stops - OMG - it was like a wallaby on steroids !

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I think fault needs clearing before correct operation resumes

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That's right. It's gone into hard fault so the ECU has shut the system down to protect it. It won't do anything until the fault is reset. That is all the EAS Kicker Lite does, resets the fault but doesn't give any indication of what the fault was. Complete waste of money at the best part of £80 compared with a cable and the EASUnlock software.

If the compressor runs with the jumper in place and you have continuity between orange and black wires, it isn't a problem with the compressor. Or at least, the compressor is working. If it is runing but not generating sufficient air, then the ECU will have told it to turn on but the pressure switch won't have turned it off within the time the ECU expects it to so it will see that as a fault. It has no way of knowing if the compressor is worn and not providing sufficient air or if the pressure switch has failed so it shuts down so you don't risk over-pressurising the system. Or it could be a completely different fault altogether, but without diagnostics you don't know what it is.

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Joined: Sep 02 2016
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Hugh, not sure if you have also checked this but Is the relay under the passenger seat operating OK ?

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Excellent info and well explained - thanks a lot
I suspect there may be a few more inquisitive posts regarding my EAS
Hugh
2001 - P38 Bordeaux LPG

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Hi Dave, I've not checked the delay relay, how would that affect the compressor not running and the associated lifting

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Delay relay operates as soon as the ignition is turned on and supplies power to the EAS system ECU. With no power it isn't going to do anything but if you have the 4 height lights showing, then the ECU has power.

Hugh, where are you? There may be someone local with diagnostics if you haven't got the cable and your own set yet.

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If this relay does not operate Hugh, neither does the compressor, and you get all the 4 leds up and the 35mph Max message.......

( ...and I know this because I have 'nobbled' the relay (internally, and also added a switch to turn the 12v it supplies on/off) to stop
the famous 'overnight EAS dance'... Note: The 'lifting' does not happen though, the EAS stays where it was when the 12V stopped..... )

Don't have the ETM in front of me right now but I seem to recall that you can use one of the yellow relays instead 'tempoarily' (?)
Anyone else remember/try this ?

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Dave, not quite right. The delay relay supplies power to the ECU so if it isn't operating it won't do anything. The compressor gets it power from the maxi fuse or fuse 40. But, that power goes through the compressor relay which is energised by the ECU. You can swap the timer relay for a standard 4 pin but if you do you cann't connect diagnostics so you do need to keep the timer for when it faults.

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Ah yes Richard.... I remember now: it was to STOP the compresssor operating (and thus the 'dance') !!

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The dance doesn't run the compressor, it just drops 3 corners to match the lowest. Ordinarily the timer relay gets it's power from fuse 24 as soon as the ignition is switched on but it also has a source of power from fuse 29. Every few 4-6 hours it switches on, the ECU checks the heights of all 4 corners and lowers 3 to match the lowest. So if you are parked on the flat and have no leaks, all 4 corners will be where they were left and it does nothing. Even if it drops slightly due to a change in temperature, they will all drop by the same amount so it still won't do anything. It's only if you are parked on lumpy ground or have a leak when one corner will be below where it should be (relative to the others) so the others are dropped. Left for long enough, it will drop to the bumpstops or if you have a leak on one corner it will do the same.

Taking out the timer relay and fitting a 4 pin disables the timer waking up so it never checks the heights so never adjusts. So unless you always park on rough ground or have a leak, swapping the relay has no affect whatsoever. My Ascot is parked on the flat, was put in high when last used 3-4 weeks ago and is still sitting at high, it hasn't dropped at all. Where I park the ex-plod depends on where the other half has abandonded her Merc when she got home and one place results in one front wheel being on an upward slope (so that wheel is lower as far as the height sensor is concerned) so it drops the other 3 to the same number below standard.