EAS - Updated Service & Diagnostic Information
Bulletin: P93/68-002Section: Product
Date: 6/18/93
Model: Range Rover
Applicable to: USA/CND
Subject:
ELECTRONIC AIR SUSPENSION (EAS) - UPDATED SERVICE AND DIAGNOSTIC INFORMATION
The following material supplements and updates the EAS information found in the:
^ Range Rover Workshop Manual, Section 68
^ 1993 Range Rover New Product Information Book
^ Hand Held Diagnostic Unit Operating Instructions Booklet (revised, P.N. XXB886A)
^ Previous EAS related Service Bulletins/E-Mail messages
^ EAS Service Training Video tape
Refer to this Service Bulletin as needed when performing tests with the Hand Held Tester (HHT) and/or using other service/diagnostic information on the system.
UPDATED EAS DIAGNOSTIC CARD - VERSION 2.1
The Version 2.1 card improves the diagnostic capability of the HHT. The key differences as compared with the original card are:
^ Dynamic Tests - Now include additional information: Compressor thermal circuit breaker status, ECU demand height display, MPH and KPH road speed display. In addition, the information is now in a more logical order.
^ Calibration - Improved calibration accuracy due to a software change which measures 3 rather than 2 values per wheel.
^ Initial tests - The valve test section is now optional and may be bypassed when, for example, the system has no air supply available.
^ When a "hard fault" relating to height sensors has been recorded, the initial tests don't have to be performed prior to clearing the fault.
UPDATED EAS COMPRESSOR INFORMATION/TESTS
^ The compressor manufacturer has recently increased the length of the braided motor brush connecting leads to reduce the possibility of brushes hanging up and loosing continuity with the commutator. A "safe" VIN will be announced.
^ When using the HHT, the message "Compressor on indicates only that the system is calling for air. In some cases the compressor may actually not be running. Example: When the valve block is exhausting. Since the same line is used for pressure and exhaust, the pump momentarily stops whenever air is discharged from the system.
^ If the thermal circuit breaker in the compressor opens, the ECU will switch off the compressor relay feed for 3 minutes. After 3 minutes, the ECU will recheck the breaker:
Breaker now closed:
ECU supplies compressor relay feed (providing the pressure switch is calling for pressure)
Breaker still open:
ECU will prevent compressor relay feed for an additional 3 minutes. This will then repeat in 3 minute intervals until the thermal breaker closes.
^ If the thermal breaker fails in the open position it is still possible to operate the compressor with the HHT during the initial tests. Dynamic tests will, however, verify failure of the thermal breaker.
^ If a compressor is found to be inoperative for any reason, do the following before returning it to the LRNA Warranty Department:
1. With the compressor at room temperature and using a digital ohm meter, measure the following:
a. Resistance between orange and black wires.
b. Resistance between green and black wires.
NOTE:
Make sure that any resistance in your meters test leads is subtracted from the measured value. Example: Meter leads touched together = .2 ohm. Meter leads touched to green and black wires = .6 ohms. Actual motor resistance = .6 ohm - .2 ohm = .4 ohm.
The actual measured values must be written on the Warranty Parts Return tag in the comment area prior to shipment to LRNA.
UPDATED VALVE BLOCK INFORMATION/TESTS
Multiple internal changes in the valve block assembly began at VIN . . . PA627344 to improve overall reliability and reduce "valve stuck open" symptoms. Later changes included modified non-return valves.
^ When performing multi-meter tests 23-28 in the HHT Operating Instructions Booklet, you may read the correct resistance specification of 800-1200 ohms but still have a faulty valve. Performing the HHT initial tests before doing the multi-meter checks will avoid the problem and identify a valve failure.
^ Test procedure No. 37 (pressure switch test) in the HHT Operating Instructions Booklet can appear to fail if the valve block solenoid diaphragm valve No. 12 or system air operating diaphragm valve 13 are faulty. The failure of valves 12 or 13 will result in compressor air going directly out the system's exhaust. A schematic of the pneumatic valve system including these solenoid valves is found on page 19 of the HHT booklet as well as in the Workshop Manual, Section 68 and the 1993 New Product book.
^ A quick check of exhaust air leakage can be made by placing an ordinary toy balloon over the end of the exhaust hose. Any leakage will quickly be apparent. Diaphragm valve No. 12 may be tested electrically by using an ohm meter across pins 8 (green wire) and 10 (black wire) of the 13 way valve block connector. Spec: 40 +/- 4 ohms.
In any pneumatic system, a certain amount of air is lost over time. The Factory advises that a drop in vehicle height of up to 5/8" (15 mm) per 24 hour period is normal. Remember, the system will check and re-level the vehicle every six hours while parked. This will decrease the vehicle height. Temperature change will also affect height somewhat.
If excessive loss of height is suspected, perform the drop test below.
DROP TEST
1. Place vehicle on level surface with suspension at standard ride height.
2. Turn off ignition and exit vehicle. Close all doors.
3. After 20 seconds, open right rear door and activate disable switch. Close and lock the vehicle.
4. Measure and record each wheel arch height.
5. 24 hours later, remeasure to determine amount of drop.
6. Reset disable switch.
If measured drop is more than specification, examine all pneumatic components for leaks or see page. Suspected areas are: air tubing connections at valve block or air springs, valve block leakage, tubing damage and so forth.
MISCELLANEOUS EAS INFORMATION
^ From VIN . . . PA626723, the inlet air filter was redesigned to eliminate the possibility of water ingress. The correct specification filter has a solid cap and air inlet holes around the body of the filter canister. The old design had a perforated cap and solid body. The part number for the updated filter assembly is NTC9847.
^ Vehicle levelling while stationary with the foot brake on, i.e. at a traffic light, is normal after a one minute delay period. Concerned customers should be advised accordingly.