Air Suspension Field Recovery/Repair

It's hard to cross dunes on bump stopsIntroduction
Rule #1: Get to it Before the ECU goes into Fault Mode:
Driving Home in EAS Fault Mode
Restoring Operation While in Fault Mode
Leak Detection
Air Hose Leak Repairs
Compressor Field Repair
Air Spring Replacement in the Field
Temporary Repair with Wood Blocks
Height Sensor Replacement or Repair
Manual Operation if a Fault Occurs
Depressurizing the System
Disabling the EAS

More Information
 

Photo at right by Chris Crompton: Awkward situation when EAS drops to bump stops in the field.

 

 

Introduction
If (like me) you are unfortunate enough to experience air suspension problems while out in the boonies and far from your friendly TestBook-Equipped Land Rover dealer, do not panic. The increasing cumulative experience of fellow owners has provided a way around almost any problem that can occur. Even in the worst case,  if the ECU senses the fault and drops the EAS to the bump stops, and you do not intervene with the solutions covered on this page, you can still limp home in this condition. The bump stops are designed to act as crude springs, and in fact allow a pretty nimble limp, as explained in the limp home section below.  Much better outcomes than this are possible for most known faults, however, and are detailed on this page. Before getting into the details, however, an essential pre-requisite for solving these problems in emergencies is a general knowledge of the air suspension system operation and how its "brain" reacts to faults. These topics are covered on the Air Suspension Operation, Faults and Diagnosis page.

In late 2007, the situation was revolutionized by the advent of free EAS fault reading and clearing software developed by RangeRovers.net member Storey Wilson. Now, anyone with a notebook computer can survive the dreaded experienceof landing on the bump stops! Meanwhile, even if you have this latest electronic solution, the information below on how to repair the cause of the fault before you can clear it and restore normal operation.

CAUTIONARY NOTE: The EAS system uses air at 10 bar (150 psi) which is a very high pressure. Be careful when doing any operation on it; the air should be removed from the system before repairs are carried out.

See notes under "Depressurizing the System".

 

Rule #1: Get to it Before the ECU goes into Fault Mode
If an EAS problem happens in the field and it looks like one you might be able to repair, it is important to do the repair before the ECU detects the problem and goes into the "hard fault" mode ("EAS FAULT" message on the message center, EAS warning light on, and all EAS lights lit up on the height control). Once it is in this mode, it can only be reset by the dealer's Test Book, even though you may have fixed the cause of the fault. This is particularly the case with 1995-98 models with the GEMS engine control system which has non-volatile memory. On 1999-2002 models the Bosch electronics uses volatile memory, but the EAS computer faults still cannot be reset by disconnecting the battery -- this fact was confirmed during a recent incident on a 2000 model by alert reader John Angott.

If you are in an awkward spot not suitable for repair work and want to delay the evil moment when the ECU goes into this annoying fault mode, crack open a door or tailgate as you drive along or unplug the EAS timer relay, a small black box under the left front seat.  Either of these actions should freeze up the EAS and put it into a state of suspended animation until you get to a suitable place to do your repairs. If you open the tailgate, also remember to open your windows to prevent asphyxiation.

Update November 2003: I recently had occasion for (another) practical test when my air compressor went on the blink. After pumping up the system with air again, I disabled the EAS by unplugging the EAS delay timer under the seat. I then drove the car for a couple of days with no problem -- a "35 mph max" message was displayed on the dash but it did NOT go into hard fault mode. I was able to effect a repair after a couple of days and the system reverted to normal. I previously thought that removing fuse 44 was also an acceptable option, but John Hudson recently reported that doing this sent his into hard fault mode. 

 

Driving Home in EAS Fault Mode
If the problem is not fixable in the field, but you have only suffered loss of air from the tank, failure of the compressor or some other problem that leaves the car at normal ride height, you can merrily continue the journey or drive to the nearest dealer at your leisure. In this case, as an extra precaution, I would unplug the suspension delay timer relay under the front left seat to completely disable the system. This will prevent the suspension ECU getting bright ideas about lowering the suspension to the bump stops or doing any other adjustments that you don't want. Of course, if your valve block is getting old like mine, the air will eventually leak out of the springs through the valve block anyway, but that might take a day or two -- even longer if your system is newish or in good shape. Even then you might be able to pump ut up again with one of the techniques suggested below in the Manual EAS Operation section.

If you have ended up in in hard fault mode with one or both ends of the vehicle on the bump stops, do not panic. You can still drive merrily home or to the nearest dealer, even if that is a long way away. The edict in the owners manual about not exceeding 35 mph under these conditions is doubtlessly put there to protect Land Rover from warranty or liability claims -- the ride on the bump stops is a bit bumpy but on good smooth highways and freeways I have been able to keep up with the traffic flow quite well, at speeds up to 70 mph. If you are lucky and only one end of the vehicle is on the bump stops, as happens when a spring fails, the ride is correspondingly better. When my front end landed on the bump stops after the spring blowout, I had to drive 450 miles to the dealer -- I did it in 7.5 hours. When my air tank leak put both front and rear ends on the bump stops I drove over 100 miles to the nearest dealer without much discomfort and still kept up with the traffic.

Restoring EAS Operation After Repairs, Even While in Fault Mode
Note: See Also "Restoring Normal EAS Operation in Fault Mode After Repairing the Cause" and "Clearing EAS Faults with a Notebook Computer and Free Software".

One of the annoying features of the EAS is that even after you have repaired the cause of a fault (eg changed a leaking spring) the ECU remains in fault mode and the vehicle remains on the  bump stops til you can get it to the dealer to reset the fault. Thanks to Ron Beckett of Australia, we discovered that (at least with the 4.0/4.6) even with the EAS in "Fault" mode, it is usually possible to restore normal ride height if you can get the air tank full again. Ron was given this information when he had to drive a friend's RR to a mechanic with suitable computer diagnostic gear to have an EAS fault reset. (In this case the fault was caused by an air spring leak; a new bellows was fitted but of course the vehicle wanted to stay in "limp home" mode).

To pump up the car for the 50 km ride, the mechanic told Ron to run the compressor to restore system pressure by turning the ignition on and shorting pins 1 (power feed to ECU from delay turnoff timer) and 8 (power line to compressor) of the EAS ECU connector C117. (Note: To avoid overpressurizing, you can also monitor pin 13 -- when it switches up to 12 volts you are up to pressure). After running the compressor for about 10 minutes, Ron turned off the ignition, reconnected the plug to the ECU and started the car, which rose majestically on the air suspension in spite of still indicating "Air Suspension Fault". Ron then switched off, unplugged the ECU connector (C117), and drove it to the mechanic. The car stayed up and drove normally for the entire journey.

C117

C117 Jumper

EAS ECU connector C117 is located under the front of the left front seat (4.0/4.6). To access it, remove the seat base trim panel and the black plastic ECU dust cover. 

Photo of the connector unplugged from the ECU, showing which pins to jumper to operate the compressor. In this photo, the cable enters the connector from the left.


More recently, fellow owner Dennis Altman has refined this fault recovery procedure and the full details are posted on the page on "Restoring Normal EAS Operation in Fault Mode After Repairing the Cause". Even more recently (2007/8) Rangerovers.net member Storey Wilson has developed free software for clearing EAS faults using your notebook computer.

Note that other methods of restoring system pressure by jumpering other connectors are described under manual pump-up of air suspension. Ron suggests that owners could make this whole operation easier by simply installing a SPDT switch in the EAS box to make and undo these temporary connections.

Leak Detection
A can of proprietary leak detector in a spray can can be purchased from the dealer, or you can put a home made solution of soapy water on the suspected spots (usually where the air lines enter and leave the valve block) and watch for bubbles.

Air Hose Leak Repairs

air leak areasLeaks in the air hose lines
A hose repair kit is available from Land Rover to fix leaks in the air lines (part number STC8580 is the connector alone, or a kit is available with the connector plus about 10 feet of air line). The repair kit is a 6 mm one, which fits the main air lines connecting the air tank, valve block and air springs. It does not repair the short 4 mm and 8 mm lines used for the exhaust and the air dryer. I have not yet heard of anyone actually developing a leak in one of these hoses, but it is nice to know the repair can be done. According to Technical Service Bulletin 0027, leaks in the rear exhaust assembly have been known to generate enough heat to destroy the integrity of either the rear air spring lines or the reservoir line (see photo at right from the Technical Service Bulletin indicating the areas at risk). Unlike the situation i the early days of 4.0/4.6 Range Rover ownership, spare hose line is now inexpensively available from Rover Renovations.

Leaks where the hose enters the valve block
More commonly, a leak will occur where the hose enters the valve block or the spring, but this is unlikely to be a bad enough leak to bother fixing in the field. However it can be repaired at leisure by replacing the rubber "O" ring in the connection. After depressurizing you can press in the collet and pull out the hose from the offending connection. Then fish out the "O" rings with a crochet hook or a bent wire with a rounded end so as not to damage the valve block O-ring seat.

Replacement O-Rings
The "O" ring did not used to be a standard Land Rover part (they prefer you to replace the whole $800 valve block). One dealer mechanic I talked to had the dealer buy them for him. Nowadays, you can buy them as official parts (for part numbers see the valve block page), or more conveniently, buy a complete set of O rings for the valve block from Rover Renovations for under $20! 

In an emergency you can even get the O rings from a hardware store. When Ron Beckett was getting leakage from the main airline from the tank into the valve block (a fairly common leak) he measured the "O" rings and found they were 6mm I.D. and 2.5mm ring thickness. Terry Mueller found that in backward countries like the US that have not switched to the metric system, standard O rings with 1/4 inch inside diameter and 7/16ths OD work perfectly. This makes sense as the air lines are 6mm OD. He used a micrometer to check the ring thickness and a 6mm drill shank to check the ID - it was a perfect fit.)  Ron found the crochet needle as suggested in the workshop manual was perfect for removing the O-rings. For more details on the valve block see the Valve Block page.

A comparison of the O-ring from Ron Beckett's rear air spring (normal O-ring) vs the leaking O-ring from the valve block.  Note the latter (left) is patterned from being pressed against the collet for many years. The other side looks like a normal O-ring.  These rings are 6mm ID and 2.5mm ring thickness.


Compressor Field Repairs
If the compressor is working but will not get up to operating pressure (and the problem is not due to air escaping somewhere else), you can fairly easily take the compressor apart and "rebuild" it by replacing the teflon seal on teh piston with a jury-rigged part, made for example from the bottom of a plastic 35 mm film container. Details of this and other temporary ways of fixing the seal are supplied on the Compressor Field Repair Page.

Another possible fault on the compressor that happened to me was failure of its thermal cutout switch, (the third and thinnest lead, colored orange, emerging from the pump motor body), making the ECU think it is overheated. I just grounded this wire so the ECU would think the pump was not overheating, and continued on my way.

See also the Compressor Diagnosis & Replacement Page for more diagnostic assistance.

Air Spring Replacement in the Field

With the appearance of inexpensive aftermarket air springs, it is now practical to carry spares, so failure in the field is no longer an expedition-killing event. You have two options -- one is to replace the bladder only, keeping the ends or pistons in place. The bladder is now available inexpensively from most Rover parts suppliers, or direct from the US-based aftermarket manufacturer, Arnott Industries. Arnott's front bladder ($91) was originally specified for both front and rear, so should fit both in a pinch (although Arnott now specifies a new longer $107 bladder for the rear), so you can carry a single bladder for a repair to any spring. Rover Renovations now lso sells the replacement bladder at even lower prices. For more information on suppliers see the Air Spring Replacement page. The second option is to replace the whole spring assembly; this is not much more expensive and is much quicker and easier than the "bladder-only" replacement operation. In either case, stop and do it before the EAS goes into hard fault mode; see Rule 1 above.

Field Replacement of Bladder Only
Tire irons can be used to remove the bladder from the spring ends. Andrew Parker gives full details of the bladder replacement operation in our section on "Air Spring Bladder-Only Replacement". The operation is easier to carry out with the spring removed from the vehicle and at a location where the spring piston can be held in a vise. However, Andrew has also tried it with the springs in place on the vehicle for practice. He reports that the front bladders can be replaced with the top and bottom of the springs still attached to the chassis and axle respectively (as long as you remove the wheel arch liners first), but to do the rear it is necessary to remove the entire spring as it is not possible to get levers in at the right angle to pry the bladder off the top spring member. 

Field Replacement of Complete Spring
Carrying complete spare spring assemblies -- one for the front and one for the rear -- makes for a more bulky "spare parts" box, but a much faster field repair (faster than changing a broken coil spring). Procedures for changing an air spring are fully described on the "Air Spring Replacement" page, but keep in mind that these and the official instructions assume access to a normal garage with one or two floor jacks and a set of axle/chassis stands. Without these facilities, you can't get the wheels off while supporting the chassis. Having had to replace an air spring in the field without these luxuries on hand, or even any rocks in sight to rest the chassis on, I offer the following modified shortcut method based on hard experience, leaving the wheels on.

John's Field Replacement Shortcut
1. Open rear hatch or a door to immobilize the EAS computer, and jack up the chassis at the affected corner to about "High" level or a bit higher.
2. Release clips at top and bottom of spring**, then release air line (push collar with screwdriver while yanking on air pipe). Careful of air blast.
3. Manoever old spring out and replace with new one. For front spring, lower jack enough to make spring top and bottom connect to fixings without bending off kilter. Attach clips and shove airline into fitting.
4. For rear spring, leave jack high for access. Insert new spring in top mount, supporting its lower end as needed to bed top evenly. Insert top clip and air line, then insert lower end of spring in mount and insert bottom clip.
5. Lower jack so corner being worked on is below normal. Start engine, shut doors and allow vehicle to pump itself up off the jack.

**The top clips are the only tricky part. For pictures of their locations see the air spring replacement page. I find it easiest to access the front ones with the fingers; the inboard ones can be reached via the engine compartment. For the left, removing the engine air intake assembly (very easy) from the plenum greatly improves access. For the outboard top clips on either front spring, reach up behind the plastic wheel well liner (bend it outwards  a bit) for easy hand access. For the rear, you can see the "R" clip in the crack between the chassis and body after jacking up the chassis. You cannot reach it with your fingers so use a bent piece of wire to yank it out. Or, use a pair of pliers inserted horizontally to grab the top of the clip. Pliers can also be used for holding the clip while shoving it back in again.

woodrepair

 

Temporary Repair with Wood Blocks
If you are in an off road situation when the failure occurs and need more clearance than available when the system drops to the bumpstops, you can do as Chris Crompton did when his failed in the Abu Dhabi desert -- just jack up the car and tape some wood blocks (or any other material that is strong enough) under the bump stops! (See photo at right). For full details on this technique see the Air Suspension Field Repair with Wood Blocks page.

Height Sensor Repair or Replacement
If a height sensor appears to have gone bad in the field (eg by the ingress of water), Bill O'Brien reports that you can remove, disassemble and clean them. He suggests prying the back off and cleaning with carbon tet or volume control cleaner from Radio Shack. Reseal the back with silicone. Peter Sanders checked his height sensors on his (94 Classic) RR and found that one of them seemed to have what sounded like  "grit" inside. Because of this and the fact that the relays were being  operated on/off quite rapidly he decided to take the sensor apart. He carefully took the back off to examine  the "innards", and found they are very well made and do appear to have a very long life. They are made with two  potentiomer "circuits", so they can work on either side of the  vehicle. Thus, you can double their life span if you do as Peter did and swap them  from side to side. I am not sure if this is the case though with the 4.0/4.6 sensors

Manual Operation if a Fault Occurs
It is possible to operate the EAS manually with jumper wires in an emergency. It is also possible to get the compressor to run using jumper wires. For details of these  procedures see the Manual Suspension Pump-up page.

A second approach was also successfully tried by Mark Hudson when his compressor needed replacing (but before the system went into hard fault mode). He found that "Before I replaced the compressor I was able to air up the suspension using my compressor at home.  I simply disconnected the compressor air hose and slipped a plastic tube over it and clamped it the best I could.  Air leaked out like crazy, but I was able to air up the bags and they stayed up due to the back-flow preventer valve". (Note if you have the same problem as Mark did while in the field, you can temporarily "rebuild" the compressor by replacing the seal on its piston with a jury rigged part; see the Compressor Field Repair Page). 

Another manual option is to instal an EAS override system prior to venturing out. Mike Ferguson added standard tire valves to each of the 4 air lines, so he can manually pump up the suspension using any standard tire pump or air supply. Details of his modifications appear on the "Manual Suspension Pump-up page. Airbag Man in Australia (worldwide shipping) supplies an inexpensive Range Rover Safety/Emergency Kit with isolation valves, inflation valves, tubing, and instructions that allows you to pump up the springs individually from any tire pump. Another manual option is to instal an EAS override system prior to venturing out. The Black Dog Air Valve Conversion Kit available from MotorcarsLtd also includes standard air fittings that allow you to plug a regular tire pump in to the air line for any spring and pump it up to the desired height. More recently, the Manual Air Recovery System (MARS) allows the same functionality for a lower cost.

Depressurizing the System
The manual advises depressurizing the system before replacing components such as springs. Their procedure for doing so requires the Test Book. However if you are in the field with a blown air spring, obviously the spring itself will already be depressurized. You can depressurize the air tank by SLOWLY unscrewing the drain plug -- it has a notch in the threads so when it is part way out it lets the air escape without firing the plug out like a bullet.

As Dennis Altman points out, an alternative method is to de-pressurize the system using jumpers. To do this, access the main EAS ECU connector under the front of the driver's seat -- see the section on Manual EAS Valve Activation. Just connect all the valves (pin 9,10,11, 26, 27 and 28 on the  she'll settle down nicely, and dump the tank for you.

 

Disabling the EAS
For many repair operations you don't want the suspension to be adjusting itself up and down while you work on the vehicle. Classic air sprung models have a disable switch under the seat, but this is lacking on the 4.0/4.6. On these models, the following options are available for disabling the system:
1. Leaving a door or the tailgate open effectively freezes the suspension
2. Unplug the air suspension delay timer, a small black box that looks like a large relay under the drivers seat. See Air Suspension Disabling on the air spring replacement page.  
 

More EAS Information
Range Rover Suspension Details and Mods
Replacing an Air Spring
Air Spring Replacement (Bladder Only)
Arnott Generation III Air Spring Upgrade: firmer on hwy, softer off road and more travel
Clearing EAS Faults using your Notebook Comouter
Compressor Diagnosis and Replacement
Compressor Rebuild Procedure
Compressor Field Repair / Temporary Rebuild
EAS ECU Interface and Diagnostic Cable Details
Valve Block Details and Repair
Disabling the EAS
Emergency Bypass of EAS
Extended Profile Selector
Lifting the Air Suspension
Manual Pump-up of Air Suspension
Parts Sources for EAS Components
Repair Details
Replacement with Coil Springs
Restoring Normal EAS Operation in Fault Mode After Repairing the Cause
Low cost and generic parts sources (including suspension parts)
Strutmasters US maker of alternative air suspension parts; low cost supplier of Range Rover air spring bellows.
Airbag Man (Low cost Australian supplier of RR air suspension springs, compressors, parts. Worldwide shipping).
Arnott Industries (makers of air spring bladders)

Andy Cunningham's Air Suspension Operation Page
Andy Cunningham's Air Suspension Troubleshooting page
Mechanical and Electrical Upgrades

 

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Page revised February 2, 2012