Jump to content

How to fool air suspension?


Jon White
 Share

Recommended Posts

Ok this could be an interesting one........

Need to get me new toy (94 classic rangie) onto a ramp tomorrow to fix it. Only trouble is where its been parked up for a while the air suspension is now sat on the bumpstops, and I can't get it onto the ramp as theres not enough ground clearance!

So far as I know the air suspension works, but as the engine doesnt run I cant get it to pump up the suspension (its not supposed to work until it detects that the engine is running at more than 500 rpm). Apparently it detects this from the tacho output on the alternator the same way as the rpm counter does (its 300tdi).

So has anyone got any ideas how i can fool it into running so I can get it to lift to standard ride height?

I've had it suggested that I could disconnect all 4 air lines from the valve block and fit them with valves and inflate with an air line manually, but it seems alot of agro if theres an easy way to do it by, say, shorting a couple of pins on a plug together somewhere!

Otherwise I thought - connect compressor wiring direct to a spare battery to pressurise the tank. Then disconnect the ecu and put 12v accross the wiring to each solenoid valve in turn to get it to lift. However i dont have a wiring diagram for it!

Anyone ever been here before or got any bright ideas?

Thanks

Jon

Link to comment
Share on other sites

Much easier than that - just stick a decent battery in the truck, then disconnect the connector from the EAS ECU (under the drivers seat, above the engine ECU, I think - if yours is a soft dash may be moved. Think the engine ECU moved to the right of the footwell, but not sure about EAS). All the ECU does is switch 12V lines, so you can operate everything with jumpers across the connector.

Link to comment
Share on other sites

Here's the pins you need. Link taken from www.rangerovers.net, which has quite a lot of practical info on the EAS system.

I'm afraid if the EAS has been left without power for any length of time it'll need fully recalibrating on a diagnostic system, as it's backup power is only a capacitor. That said you can manage without it - mines been MIA for about nine months, I just manually inflate the suspension to whatever height I want and level it up once a week!

Must get that sorted properly sometime... :rolleyes:

Link to comment
Share on other sites

oooooooooooooooohhhh perfect!!!!

Thanks Geoff!!!

So my guess is then that once power has been disconnected for any length of time it looses the height sensor settings so has to be re-calivbrated with testbook - correct?

i'm kind of guesssing then that this will have to be done on mine as the battery is as flat as a very very flat thing......

Cheers

Jon

Link to comment
Share on other sites

So my guess is then that once power has been disconnected for any length of time it looses the height sensor settings so has to be re-calivbrated with testbook - correct?

'Fraid so :(

It's probably quite expensive to get it done by a testbook equipped garage, as the classic apparently has to be jacked to the appropriate heights and the sensor readings stored. I think Rovacom allows the vehicle to be raised and lowered from the diagnostic system by operating the suspension, which would, I guess, save quite a bit of labour.

Unfortunately there's no known way of calibrating the EAS without a diagnostic system.

Link to comment
Share on other sites

Bugger............oh well!

Seems a stupid idea to me - what you're basically saying is that if you left your lights on and flattened the battey you have then to get the suspension re-calibrated!

Daft idea........

Got a couple of mates who will have access to some sort of diagnostics so shouldnt be too hard to get sort out!

Thanks

Jon

Link to comment
Share on other sites

Seems a stupid idea to me - what you're basically saying is that if you left your lights on and flattened the battey you have then to get the suspension re-calibrated!

Daft idea........

It won't get wiped immediately - not sure exactly how long it maintains its memory. Mine was left unplugged for a couple of weeks.

On the whole the air suspension works very well and the hardware is very easy to work on - I've only found it to have two major failings, but they are both big ones. The first is the volatile memory (it only saves a simple set of voltage values - I'm sure it wouldn't have cost that much to use non-volatile), the second is the way you can't reset it after a major fault. This is what it's really notorious for - if a fault code is thrown you have to reset it using a diagnostic computer, and if it's a major fault (most things you're likely to do to it in the field, including putting a sensor out of range) then it'll drop the truck on the bump stops until the reset. I don't know who thought that was a good idea, but they need some common sense beaten into them...

So far as I know, the current land rover EAS systems still suffer from this design flaw?

Link to comment
Share on other sites

Ah - this one has been parked up for a coupe of months with a flat battery........

Daft idea really...........volatile memory is pointless for something that has to retain settings! At least the procedure you liked me to would do as a get you home type fix if it all goes horribly wrong out in the wilds..........

Is there a cheapo DIY type diagnostic unit on the market that'll work? I know rovacom is available, but IIRC it still costs in the region of £400!

Jon

Link to comment
Share on other sites

Ah - this one has been parked up for a coupe of months with a flat battery........

Daft idea really...........volatile memory is pointless for something that has to retain settings! At least the procedure you liked me to would do as a get you home type fix if it all goes horribly wrong out in the wilds..........

Is there a cheapo DIY type diagnostic unit on the market that'll work? I know rovacom is available, but IIRC it still costs in the region of £400!

Jon

If I knew of one I'd have it :(

I did once price up a Rovacom Lite with the modules for my truck - came to £1000...

Link to comment
Share on other sites

Sigh mutter grumble..........ah well..........

Think i might do all the jobs i need to on it first and then get it recalibrated once its all done, cos otherwise knowing my luck it'll wipe itslef again if I disconnect the battery to do some welding or summat......

Thanks for your help!

Cheers

Jon

Link to comment
Share on other sites

Guest diesel_jim
'Fraid so :(

It's probably quite expensive to get it done by a testbook equipped garage, as the classic apparently has to be jacked to the appropriate heights and the sensor readings stored. I think Rovacom allows the vehicle to be raised and lowered from the diagnostic system by operating the suspension, which would, I guess, save quite a bit of labour.

Unfortunately there's no known way of calibrating the EAS without a diagnostic system.

Obviously Land rover went and grabbed the nearest village idiot to design this system then!

Link to comment
Share on other sites

Ah - this one has been parked up for a coupe of months with a flat battery........

You might be lucky - mine didn't go completely (to start with). It behaved erratically for a while and intermittently displayed a soft (non-critical, just stay at standard height) fault, which a mate who's an electronics engineer reckonned was probably a corrupted register, then after about a month of increasingly strange behaviour* it developed a hard fault and wouldn't play any more :(

A spare ECU I have (no idea how long it's been without power) just displays a hard fault if it's plugged in.

* - This included dropping the truck on the bump stops while the inhibitor switch was on and a door open, both of which are supposed to lock the suspension in its current position. Be warned - alway stick some axle stands under the chassis if you're working under an EAS truck!

Link to comment
Share on other sites

I've done a reasonable amount of work on these now, IIRC the system will tolerate a single fault, depending on what it is it may stick in normal height, but if the system develops a second fault it goes down on its knees. Golden rule "if you get a fault fix it before you get a second one".

But back on topic, fit a good battery, remove the compressor relay and bridge it (the two heavy wires) get some air in the tank and it should come up, I think. I would not run the compressor for more than about 5 minutes, 10 at a push because I'm not sure if the tank has a relief valve. The system also re-levels automatically every 4 hours so leave the battery on it for a while and it may even sort itself out, would be quicker with diagnostics though.

There must be someone around you way with either T4 (or the old lucas handheld unit that would also do it) who would reset it for you at a reasonable price.

If the sensors do need calibrating these old girls don't need blocks, the system sets a standard height and you measure round the wheelarches with a tape measure and tweak the settings until it sits level.

HTH Shaun

Link to comment
Share on other sites

Hmmmmmmmm well I tried the procedure Geoff linked me to, but couldnt get the pump to run at all. Checked all the fuses, got the hump with it and went with lumps of 4x2 between the chassis and axles for the time being.

Be interesting to see if it actually works at all once the engines fixed!

Cheers

Jon

Link to comment
Share on other sites

I would not run the compressor for more than about 5 minutes, 10 at a push because I'm not sure if the tank has a relief valve.

I'm fairly certain it doesn't - however, if you're operating the system by jumpering the connector one of the pins is the pressure sensor input to the ECU - it's normally 0V, goes to 12V when the tank is up to pressure, so you can stick a meter between that and ground to monitor it. Can't remember which pin, unfortunately, so you'll have to look it up.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy