The Rover Air Suspension Knowledge Base
- Preface -
Range Rover EAS ("electronic air suspension") has typically been an expensive system to maintain. Certainly we can offer a kit to replace the entire system using normal coil springs. Many really like and use the system, however, or bought a Range Rover simply in order to have its advantages. We offer this page for those folks, and less familiar mechanics, as well as to point out that as time has passed, many of the typical faults these systems encounter can either be overcome, or worked around. Many improved parts are now available, and information, such as found here, is available, and so the costs of operating the system have come down.
The details below refer primarily to [P38a] New Range Rover (95-02) and not Range Rover Classic (93-95), though the systems are very similar. Discovery II and Range Rover L322 ('03 - on), and LR3 EAS ("SLABS": Self Leveling Anti Lock Brake System - integrated EAS and ABS) are entirely different. Few Classics remain with their EAS intact, and Disco EAS is fairly simple and trouble-free, but please feel free to email us with specific questions for any Rover system not covered herein.
* Compressors (Air Pumps):
Rebuilt in-house by hand, compressors usually run about $250 for P38 and Classics when you send you old one in. Turnaround is usually about 3 days. One year warranty. Our rebuilds all include the rear bushing and brush box upgrades. We can also repair most LR3 and New Range Rover pumps. See Services below.
* Compressor (Air pump) piston seals:
Order info here New hi-tech material lasts longer. !!Requires special tools to replace!!
* Compressor (air pump) stainless steel lined cylinder.
Order info here Sleeved cylinder is sold exchange. This upgrade is worthwhile during any rebuild, but especially when the old cylinder is scored or worn through the anodize; also if thecompressor will be used to air-up tires. Bulletproof!
* Compressor (Air pump) thermal breakers (orange wire):
Order info here. Not the original part! Can be fitted to the outside of the pump in about 10 minutes, or inside like the original one in about an hour. Works best mounted on the outside on the cylinder head. Requires solder.
* Air pump piston bearing:
Click to order Requires special tools to replace.
* EAS inlet air filter.
Order info here Change each year or so.* Seals for air pipe. Complete kit 4mm, 6mm, 8mm
* Quick release couplers to repair air pipe (below leaky battery, for example), 6mm (and 4mm)
* Coil spring conversion kit ... if you're really fed up. Includes the over-ride wiring for turning off warnings and beeping and lights. Call 520-294-3572 for prices and options, or email Falconworks Parts.
Typically, EAS faults fall into 5 areas:
1) Leaks. Air leaks overwork the pump and eventually set fault codes, or damage the pump, or both. If the truck starts going down overnight, check for leaks using a spray bottle with soapy water in it. If no external leaks, and the problem is one or two corners of the truck, internal valve block leaks are possible: check the suspect solenoid plunger for a cracked seal. These are easily replaced. Always check all line connections, all bags, and the outside of the valve block when a leak is known to exist. Find and fix the leak. Air springs themselves only last 4 or 5 years before developing myriad pinhole leaks: no magic bullet here.
2) Unseated bags. Tyre stores' chassis lifts! Either the truck has been put on a chassis lift and pulled the springs off their seats, and/or the springs are too old and crusty and keep removing themselves when not under pressure (fully down). Re-seating a spring is like re-fitting tyre bead-seats: clean the areas which need to seal; push them in place; apply air pressure to do the work. Arnott's extended (longer) clamped-end bags fix all unseating problems.
3) Air Compressor Pump faults.
a) on deadhead pressure test, the pump should make 175psi in a few seconds (normal system cutout pressure is 148psi). Test this directly on the blue outlet hose. If not good, it likely needs a new piston seal. DO NOT replace the pressure switch because Autologic told you to do so! Test it. They very rarely fail, and are expensive.
b) if the pump should ever 'short-cycle' - run for a few seconds and then stop - the fault is in the motor. There is no Autologic or Testbook code for this fault. Remove the EAS relay and short across pins 30/51 and 87 in the main fuse box to prove the point and make the pump run so long as you like. If now OK, the brush-end bushing in the motor has come loose and needs expert attention. You can remove the brusholder by drilling the four stakings at .089" and chamfering. Tap the holes to #4x40. Repair the bushing mount and fully stake. Clean and oil the bushing and felt wick. Repair the brush holder cracked solder joints and discard the loose plastic ring which did the damage (it is redundant ... really). Test the black box - the Thermal Breaker - by making sure it has continuty across its pins when it is cooler than 230F. Refit the brush box with new 4x40x1/4 screws.
c) all codes are cleared and the computer won't run the pump, but the relay bypass in (b) above does run it. Check the relay, we've seen a few of those fail, but more likely ... we've seen the fuse box itself fail - with regularity: see our main page under Rover Problem Solvers, P38a fuse box. Really though, the fault will usually be the thermal breaker within the pump. This grounds the orange wire (from the compressor) when NOT overheated, granting permission to the ECU ("electronic control unit", AKA "module" or "ECM") to power the compressor relay if the pressure [switch] is low state. If grounding the orange wire (NOT to the pump body, but to a known good earth) makes the pump run, just replace the breaker. These usually fail when someone applies power to it while trying to hotwire the pump run, or when the rear motor bushing falls out and beats up the solder connections to it (as observed in "b", above).
4) Lack of maintenance. Periodic maintenance is required each 30k miles at minimum, and more often in unusually dusty or wet conditions, and includes:
- --Drain air tank
- --Replace inlet air filter
- --Check desiccant/drier for saturation. Replace if wet.
- --Inspect springs for cracking. Replace in pairs when any visible deterioration is present.
- --Leak check entire system including valve block and fix any leaks NOW. If any corner of the truck goes down overnight, fix it before it takes out that whimpy little air compressor!
- --Fuse box internal faults
- --Butchered wiring
- --Bad door switches (located inside each door latch) will shut down the EAS
- --Liquids spilled under the driver's (LH) seat filling the EAS computer (ECU)
- --Bad 35-way connection at ECU: erratic or meaningless fault codes and/or persistent no-comms. (e.g. height sensors never fail) See diagnostics, cat #5 below, tip #4.
Falconworks in Tucson is a Range Rover repair facility with an engineering, fabrication, and machine shop, and also a dealer for various Land Rover suspension and driveline components. We service Range Rover ABS pumps, accumulators, and pressure switches as well. We also sell our unique parts online, and offer mail-order by phone: Call 520-294-3572 for orders or email us. We accept VISA, Discover and MasterCard only. At our online shop (Jewellamberoil.com), however, we can also accept Paypal.
- --EAS air pump repair. Most compressors (through '02) have only the two basic faults and can be repaired for about $250 plus shipping.
- --EAS air pump overhaul. (See PARTS section above)
- --Testbook. If you are in Tucson, we can:
a) Simply clear codes after you have done repairs or modifications.
b) Run diagnostics less costly and far more valid that you will likely get at the Dealer, who uses the same tool!
c) Repair any aspect of the Land Rover including EAS and ABS (except paint, body, upholstery)
d) Calibrate ride heights to suit your needs.
Everything here on out is for Range Rovers, 1993 to 2002 only: does not apply to Discovery 2, New Range Rovers, or Land Rover LR3.
Electronic Air Suspension faults fall into five basic categories as follows, and generally make good sense. For all faults which don't make sense (system has no air leaks, tested strong pump running long cycles [a few minutes each] at reasonable intervals [only after using up air (e.g. increasing ride height) or otherwise each 5 minutes or more], relatively new fuse box) please perform the mod to the 35-way connector described below under cat-5, tip #4, before pursuing!!!
- The truck is up or down, no Message Center warning, and one or two height lights are on solid, but the height of the truck doesn't match the selected height, and no new height selection results in any actual change activity.
- The truck is up or down with no Message Center warning, and the selected height light winks as though attempting the correction ... forever.. New selections are accepted but the actual height never changes in the up direction.
- The truck full-up or down with "EAS FAULT" on the Message Center, and the four height lights are on solid as during start-up; will not respond to height control button selections.
- The truck is down with "EAS FAULT, 35MPH MAX" on Message Center, and the height lights as all winking, and perhaps an obnoxious beeper operates every few seconds.
- Same faults as any above except that when connecting a Rover diagnostic computer, it cannot interface with the EAS ECU, or when it does it has coded the impossible.
Category 1 faults:
Disabled normally. The system is normally disabled under certain circumstances such as open doors or brakes applied. Check owner's handbook for details. However, if a fault is the cause it is usually that a door switch is indicating an open door (look for dome lights on, and Message Center warning) when its actually closed. Fix the switch or replace the latch. No amount of door adjustment will address this problem.
Category 2 faults:
These categorically lie on the switched side of the EAS pump relay and are open circuit. Here the EAS ECU believes the pump is running since, by all inputs, it should be. It believes pressure will eventually build and does not fault. Eventually the ECU will figure out that nothing is happening in terms of expected height-change, and will set hard or soft codes, but for right now all you need to do is fix the problem. Typically:
- Bad pump relay
- No power to pump relay (fuse box faults (open circuit), or fuse)
- Burnt-up connector(s) at pump
- Open circuit pump (no continuity between black and green wires)
Category 3 faults:
These are intermittent faults which have not been persistent enough to convince the EAS ECU to set a "hard code" and disable the system for its own sake. These are known as "soft codes." Occasionally they will go away on the next ignition cycle. Once the system is repaired these will also go away by themselves. If you have soft codes and fix the truck quickly enough, then proprietary computer interface will not be necessary. Although insidious intermittancies could be culprit, typically these are caused by:
- Small air leaks which cause the pump to run too long and repeatedly thermally cycle off.
- Weak pump which thermally cycles because it takes it too long to replenish air in normal operation.
- Erratic height sensor or poor connections to one
- Continued use of system when compressor is erratic from a) fuse box faults, b) brushbox faults, c) low output, d) genuinely faulted pressure switch.
Category 4 faults:
These involve hard codes and cannot be cleared, even after repairs, without Testbook or Autologic: proprietary interfaces. You may as well have the system scanned on the computer and see what is in memory. Often we see what are generally bogus codes (stuck solenoids, bad height sensors and pressure switches, to name a few), but they still need to be cleared from memory before the system can work again. There are no tricks for turning off the 35MPH MAX warning with the fault in memory in the ECU and the ECU connected. Typically here you are looking for massive air leaks or other obvious problems:
- Unseated air bags (springs)
- Ruptured or massively cracked bags
- Air pipes broken or utterly un-sealed at junctions
- Height sensor control lever utterly torn from its joints or badly bent
- Cut or disconnected wiring or damaged (from abuse) pin connectors
- Persistent ignored Category 3 problems
Category 5 faults:
Here the ECU will not talk to the diagnostic computer. Once we saw leaky heater core "O" ring seals leak enough coolant onto the OBDII diagnostic port that it corroded the connectors and we couldn't interface, but generally this is more simple. There is some beat-the-system trick being touted on the net where you short pins on the EAS ECU connector to air the system up even when Rover has hard codes, and it works if the system is air-tight, but we have seen any number of burnt delay relays as as a consequence, and the occasional ECU. If you are a user of Autologic or Testbook and cannot interface, we advise checking power and earth at the EAS ECU, and power at the Delay Relay, and if OK, substitute a Delay Relay.
The no-comms fault is typically:
- Burnt out fuse (24, 33, 44)
- Fuse box internal faults (common)
- Delay relay (common)
- Pins not fully home on 35-way connector into ECU: All ANR4499 Control Units (ECU) were made incorrectly it seems. Crooked assembly jigs result in the hook-end of the connector not fully engaging the pins. DO THIS MODIFICATION BEFORE PURSUING ANY INTERMITTANCY OR BOGUS FAULT CODES: Remove the rubber seal for the connector and thin it up by 1/2. Now you can push the connector fully home. (chronic)
- EAS ECU (it happens). A known-good substitute in the only trouble-shooting method: sorry. We'll "sell" you a test unit if you want, and if it doesn't work out, and you return it, we'll refund you less a "rental" fee of $50. Shipping and handling (both ways) is on you, however.
- ECU connector block missing the side packing strips that keep the terminals fully in. Hmmmm.
We do not recommend shorting pins (electrical connections) together. While you can fake out the system, you can also often burn out expensive bits. If the system has big enough leaks you're going home on the bump stops (fully down) any which way. The safest thing to do is find a garage with a compressed air blower nozzle and floor jack (the most basic shop-stuff on the planet):
Disconnect the multipin connector to the valve block, at the front RH corner inside the plastic EAS pump box (LHR corner of the engine bay). You can leave the other one, with only 3 wires which goes to the cylindrical pump, connected. While there, also note the numbered ports with hoses, on the outside of the box and facing the engine, and locate #1, #2, #3, and #4. To remove air hoses at connections simply push and hold the small brass collar all the way AWAY from the hose, and simultaneously pull the hose out. To refit the hose just push it in until it stops.
- Have them lift the front of the chassis from the support in front of the radiator until the air springs are tall but not pulled from their seats.
- Check the springs are fully seated, top and bottom, and re-seat if necessary.
- Remove hose #3 and with a rubber-tip nozzle blow air into it until the truck stops rising.
- VERY quickly and calmly refit the hose before too much air is lost.
- Repeat the process for hose #4.
- Remove the jack from the front and lift the chassis in the rear under the trailer hitch, extending and inspecting the rear springs in the same way as the fronts.
- Repeat steps 3 and 4 for hoses #1 and #2.
- Lower jack.
Here it is. This is THE NOT RECOMMENDED procedure. It can air up a system which has hard codes ONLY if it also holds air AND has a working pump AND has a fully functional valve block (solenoid valves and amplifier). It does not and can not reset the ECU. Any mistakes will fry expensive things quickly. Never put bared wire or implements into the connectors as they (the connectors) deform very easily: use ONLY properly formed male connectors of the correct width!!!! If a tech later needs to try to locate a bad or intermittent connection from a bent pin connector it could take days of labor, and you'll be converting to coil springs BEFORE he/she is done! Do Not short any pins ever when the ECU is connected!
Make up a jumper assembly with 4 wires soldered together on one end, and with a standard Bosch Injection male pin connector on the other. This will enable the connection of 4 pins simultaneously.
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.
- PIN #1 is hot
- 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.
- PIN #9 is the exhaust solenoid. When powered it lets air out of whichever spring's solenoid is also powered.
- PIN #26 is the inlet solenoid. Similarly it lets air into whichever spring's solenoid is also powered.
The springs' pins are:
- LHF #10
- RHF #27
- LHR #11
- 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.
Leave the ECU disconnected or it may take you right back down into your hard fault state.
When you have a diagnostic computer fitted to the system TELL THEM WHAT YOU DID, as that may save alot of grief and cost from diagnosing a no-comms fault or damaged delay relay, or pin connectors.
Prices stated here are current through 8/15/12. Gotta love Rover Madness! This it for now ...