P38 EAS head scratcher - long post

Hi guys
I was originally on the lr4x4 forum but was suggested to come here as there are a few more experienced owners

I have a small LR repair shop in Canada and specialize in Defenders and Discos, and been in the biz 15 years here so soon as folk know I am a Land Rover man, they bring their cars here rather than the dealers (stealers)

Anyway a rather nice P38 turned up on a tow truck a few weeks back and the customer pleading with me to fix it – I originally said no as I have had lots of electrical problems with P38’s due to the amount of salt on the roads. They eat up shop hours and I never can charge for the time I really spend.

Anyway I took it in as it was pretty quiet and had a look what others have done

The compressor and valve block were factory replacements from the stealers and all 4 air bags have been replaced – I should mention this is on the bump stops, and a few garages have prodded and poked at it

So first job was to check the fuses and relay – this was done by substitution – when relay was out I jumped it and the compressor was working and pumping fine.

Under the dash there was a switch that ran to the relay to power it up without the ECU – this has now been removed.

So next was to plug in the Lynx system and see what faults were showing – strange – no faults. I did a reset anyway as I had it hooked up and went to operate the valves in the block to hear them clicking – nothing

Status said the inlet was open as the 2 x rears

Anyway nothing. So I checked out the wires from the ECU to the Driver block – these were looking sad, but serviceable (been prodded with test probes)
So the compressor was running but not on its own, so I tested the overheat and that was good

So last resort was the Driver pack – now I have a paper here from LR on the EAS system and it seems the Driver pack converts 12 volts to a pulse wave at 24 KHz so to test the output of the Driver pack needs an oscilloscope – not the sort of thing you have in the tool box

So I mentioned my findings to the customer and he asked me to get a new one as I have no access to known used parts to substitute – this make fault finding very difficult

So I fitted an OEM unit from Allmakes and now the compressor runs on its own as it should doors closed engine running – but not a dicky bird from the valve block – compressor runs but you can tell it is working hard I cannot hear any valves clicking

So as last resort I followed Falconworks suggestion of the following:

For P38a, below the LH front seat are two stacked ECUs. The lower one is the EAS ECU (control module). On the left hand side is the system relay (small black box). For Classic the components are under the RHF seat. Disconnect the relay. Gently un-latch the 35-pin connector on the front and swing it out and off its hook. Remove the forward cover from the connector so you can see the pin numbers molded into the side of the connector: it slides off endwise and requires no force. Collect the two loose insets - do not misplace them, you can't order new ones. The pin numbers are molded into the back of the connector.
1. PIN #1 is hot
2. PIN #8 goes off to power the pump relay. The system overpressure switch sends its information to the ECU: when you run the pump without an ECU connected you have NO OVERPRESSURE PROTECTION. Only connect this pin to power when you know you need more air.
3. PIN #9 is the exhaust solenoid. When powered it lets air out of whichever spring's solenoid is also powered.
4. PIN #26 is the inlet solenoid. Similarly it lets air into whichever spring's solenoid is also powered.
The springs' pins are:
1. LHF #10
2. RHF #27
3. LHR #11
4. RHR #28
To go up fit jumper to pins #1, #8, #26 and one of the springs. Refit the relay. Remove the relay when done. Rewire for the next spring and repeat the process.
To go down fit the jumper to pins #1, #9, and one of the springs. Refit the relay. Remove the relay when done. Etc

I can turn on the compressor but the valves don’t work - so a buggered valve block I think – so I used a 9 volt battery and powered up each solenoid separately for a split second – there was a click from each valve so they ‘work’ but not from the above test – which got me thinking over the weekend – if the plug is disconnected from the ECU to do this test above – where dose the Driver pack and solenoids get ground from?

Naturally I checked all the grounds in the EAS plastic box when all was together – no problems

So I am running out of ideas – could it be the new driver pack is not working?
The delay timer – could this be on the fritz?
I originally thought the ECU was acting up, but when trying to operate the valves using the Falconworks method there is still nothing

I had to close the doors or Sat afternoon and walk away as it was draining my will to live

As a note the customer bought this car cheap with this fault and was willing to dump some cash into it as it does look very nice

Will have another attack Monday, and check the ECU outputs to the driver pack, so any suggestions would be appreciated!

So haven't tried the free eas unlock suite? might tell you what it is

Do you have any messages on the dash display?
If you do the eas will do nothing untill reset and dash fault message gone
Pm datatec he can supply the cable to connect to a laptop it gives you abit more control that the regular fault readers

Check all the doors as a duff micro switch will stop it operating, the timer relay under the seat will also stop it.

'the timer relay under the seat will also stop it'

You can check if this is working by pulling the ECU plug and checking for 12v at pin 1, it should be live even with ignition off.

If there's no power you can temporarily substitute the timer delay with a standard green 5 pin relay.

Alastair

Thanks for the replies
The Lynx is pretty capable and has worked fine on the EAS on other jobs

There are no faults logged in the ECU

There are no error messages on the dash and everything behaves as normal re lights on dash (the inflate light when pump is running, and the height selection switch shows constant light on low and flashing light on the STD height)


I will check the delay as soon as I open up the shop this morning

As for door switches - I assume them to be working as the pump runs when the engine is running and the doors are closed. BUT do the switches inhibit the running of the valve block?

I found out this car has been like this for a loooong time - over 2 years, left outside in temps from -30 to plus 30C, so I wonder if the height sensors are defective or out of range?
One thought I had was to manually get some air in the bags by jacking up the car to take weight off and inflate - even with a bit of air in it may make a difference

Anyway will have a go later and see what the results of my tests are

Many thanks - much appreciated replies

britrest said:

Thanks for the replies
The Lynx is pretty capable and has worked fine on the EAS on other jobs

There are no faults logged in the ECU

There are no error messages on the dash and everything behaves as normal re lights on dash (the inflate light when pump is running, and the height selection switch shows constant light on low and flashing light on the STD height)
That suggests no air pressure from the pump, it's running but have you checked it's making enough pressure?

I will check the delay as soon as I open up the shop this morning

As for door switches - I assume them to be working as the pump runs when the engine is running and the doors are closed. BUT do the switches inhibit the running of the valve block?

I found out this car has been like this for a loooong time - over 2 years, left outside in temps from -30 to plus 30C, so I wonder if the height sensors are defective or out of range?
One thought I had was to manually get some air in the bags by jacking up the car to take weight off and inflate - even with a bit of air in it may make a difference

Anyway will have a go later and see what the results of my tests are

Many thanks - much appreciated replies

Click to expand...

Lifting the car will not help amd may pop the bags off the end caps.
Check the 2 earth points on the wing between the EAS box and the air filter.

Hi - yes pump is running fine and plenty of pressure - but when started it runs up fine then you can hear it straining - plenty of pressure coming out of the dryer- not going through valve block

But again I will double check soon - will check the grounds and also if air is getting into the tank - that must mean the inlet and exhausts are opening right?

britrest said:

Hi - yes pump is running fine and plenty of pressure - but when started it runs up fine then you can hear it straining - plenty of pressure coming out of the dryer- not going through valve block

But again I will double check soon - will check the grounds and also if air is getting into the tank - that must mean the inlet and exhausts are opening right?

Click to expand...

Check the right coils are in the correct places on the valve block, there was a thread detailing this a short while ago.

You know I think this may be the answer!

This morning we plugged it all back in and left it - pump running - door open and this time took off pipe 6 and air was gushing out of the valve block - so next thing we thought of was the pressure switch - not switching off under pressure - so checked it was open circuit with no pressure (dumped tank) and then hooked two wires into the plug in place of the pressure switch - we did have 12 volts on one side and 0V the other - this seems normal

Let the car do its thing with the door open and then closed it checked the pressure switch and it went to closed - but the pump was still running - well then we thought join the dummy wires coming out of the plug and see what happens - like faking the switch - only this time with the door closed


Now get this - the rear left corner shot up like it was going to go into orbit! - at first you could have understood the excitement as the back went up as it should, but when concerned the front didn't lift we had a look underneath - the right hand rear air bag was under vacuum - so I now suspect the valves are the problem as they must be getting a signal from the driver block – so next step is to check they are in the right order

It is real funny as the valves for the inlet and exhaust must be opening but so hard to hear them click and naturally the rear left must be opening....

More after a cuppa

In my last post I said it was the rear left that went up but in fact it was the rear right

SO I checked the valves to the wiring diagram from Hard Range and they are fine
so next I put the original driver block in pump ran but nothing happened - the tank charged up but the pump kept running - I am happy the pressure switch is switching on and off - but at what pressure I have no idea - will have to rig up a pressure gauge the strange thing is with the pressure switch in manual operation the pump does not switch off – just keeps on running – so maybe the height sensors as asking the pump to keep running ? The relief valve is not passing air – but the rear right spring looks fit to burst

So with the original driver pack in and now a manual switch in place of the pressure switch, the rear left did raise but slowly this time as the pump is getting hot - so the driver block is doing the same as the new one when I manually operate the pressure switch

Just out of interest I opened the window and with the engine running I checked pins 10 and 11 on the ECU to see if they were putting and output and sure enough 12 volt on both as it says in the book – these are ECU outputs to the rear valves

Heights sensors don't ask for pump...the pressure switch does that...all the HS's do is inform the ECU of the vehicle position nothing more!

Saint.V8 said:

Heights sensors don't ask for pump...the pressure switch does that...all the HS's do is inform the ECU of the vehicle position nothing more!

Click to expand...

+1, however if the height sensors are defective, it may not rise.
Whatever, when the pressure reaches 104 to 116 psi (7.8 to 8 bar) the pump should stop.
The ECU's rarely fail, but it does sound a bit like an ECU problem.
Check the relay and under bonnet fuse box for signs or smells of burning, could be the relay is being held on by a short in the fuse box.

If I operate the pump from the ECU jumping pins 1 and 8 the pump works so I assume the circuit is working from the ECU as required

I will have to go down town and find some tee fittings for the pipework and make up a pressure gauge - I am 100% the switch is working - but not the pressure - when system empty it is open circuit, but once run the ohm meter shows the contacts closed

Before I go out (waiting for DHL to come with a package which has to be signed for) I am going to check pin 13 in the ECU to see if that is getting 12 volt from the switch - I had been checking the wires for the valve operation but there could be a break in this and maybe ECU is not getting the message to switch off - if it is - then it has to be a bad ECU

Oh and another thing it is doing which may be connected (been a while since I worked on one of these in anger) when the ignition is off and after a short while you can hear the exhaust valve blow off - so I guess this is normal to allow the pump to run with no head of pressure on start up

Funny this is the rear left shooting up on its own - and the funny thing is when you operate the manual pressure switch you can hear it come on - now I will check if it clicks on a empty system - clutching at straws now boys!

Well, I had a few volts coming down to pin 13 - but 13 V going in, so I started to have a look at the wires from the main harness to the plug that goes into the Driver pack - some dodgy wires there from others testing in the past and looks like the salt air has corroded the copper, so I would like to change the plug before I go any further with this

I think I can buy new female pins but would prefer if I could find a plug and lead used with about 6 inch of cable as this has pin holes all over - any idea who would sell such an item from a breakers and ship it here?

If not I think these plugs are called econoseal but not sure of the pin size if I get them new

Ah found the pins and plug at Polevolt! Going to make a longish pigtail and solder the lot!

Hi,
If you are sure that the problem is electrical may be worth a look behind the front kick panels. These are well known for furring up and the pins snapping inside the white connector blocks. Both sides are EAS related.

PPP38vouge said:

Hi,
If you are sure that the problem is electrical may be worth a look behind the front kick panels. These are well known for furring up and the pins snapping inside the white connector blocks. Both sides are EAS related.

Click to expand...

+1 to that. I also think that you would be better using the the EAS software from RSW as you can, for example, operate each corner individually up or down. Not sure what the Lynx capability is apart from reading faults.

try flea bay for a new block they are relatively cheap
or swap one out from one you know is working I can change one in about 15 mins
HTH

palace said:

try flea bay for a new block they are relatively cheap
or swap one out from one you know is working I can change one in about 15 mins
HTH

Click to expand...

It's not the block, it's the electronics that operate it.