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RANGE ROVER
land rover common fault
Landrover 300TDi(non EGR), Discovery 300TDi(non EGR) and V8 MFi model years 1996 to 1999
Suffering problems with the security system 'spider' ECU located within the passenger compartment. This system communicates with the vehicle Theft Alarm Unit and enables power to the starter solenoid, fuel pump and ignition coil (V8 MFi) or starter solenoid and fuel cut off solenoid (300TDi). The 'spider' ECU is a small rectangular black plastic box with 10 pin connector and is mounted behind a steel plate underneath the radio. Access requires removal of the entire dashboard!
Suspension Freezing at Normal Height (Warning Light on and "Suspension Inactive" Message)
Cause 1: Sticking Pressure Switch
The pressure switch (ANR3902) is subject to intermittent sticking, producing a false Testbook diagnosis of "inlet solenoid valve sticking". Replacement is s simple matter of unscrewing the old one from the valve block and putting the new one in with some Loktite ( see diagram at right from Technical Service Bulletin ). Even if you don't have a Testbook, shotgunning the problem by replacing this valve would be worthwhile and will very likely restore normal operation. The old switch is unsc
Cause 2: Compressor Overheat Signal
If the ECU thinks the compressor is overheating it will freeze height changes and display "Suspension Inactive". It will also store the code storing code 41 "Compressor Temperature Rises when Static". On 2003 and 2004 models up to VIN 4A155162 this can sometimes be overcome by updating the air suspension ECU software. The later software accepts higher readings from the compressor temperature sensor. Otherwise, the problem might be a faulty compressor or temperature sensor, or possibly a leak in the system causing the compressor to be on constantly.
Cause 3: Frozen Pressure Relief Valve
I think this is another possible cause of the "suspension inactive" signal. If the vehicle is already at standard height on a cold morning, it may be fine for driving but if you try to request a height change it will not respond (and might give the "Air Suspension Inactive" message until the pressure relief valve has thawed out. See "Failure to reach normal ride height" below.
Vehicle Sinks to Bump Stops.
Cause 1: ABS Switch
When the dash lights up like a Christmas tree with warning lights (ABS, EAS etc.) and warning messages ("no dsc no air suspension") on, the EAS can go into hard fault mode, slow to a crawl and settle on the bump stops. It is tempting to think the ECU has failed but that is not usually the case. The most common cause seems to be the input from the ABS system to the EAS ECU telling it to shut down. The problem can be as simple as a faulty brake switch.
Cause 2: Air Leaks
If the vehicle gradually sinks to the bump stops at rest, the most likely cause is an air leak. The early model rear air bellows are prone to leaking in cold weather or if they have been subject to overpressure.
Failure to Reach Normal height
Cause 1: Sticking Pressure Relief Valve
The pressure relief valve will often stick open in temperatures below -20 degrees Celsius, preventing the system from reaching normal ride height or responding to height adjustment commands. Normal operation resumes when the vehicle warms up and thaws the valve. Interestingly, Land Rover's solution for this is not to get a better relief valve design, but to modify the ECU software to work around the problem. The January 2004 service campaign performed this update and installed new rear air springs -- see below. Presumably the software update gets the ECU to ignore the problem til the system has warmed up.
Cause 2: Air Leaks
Especially from rear airbags on models built up to January 2004 -- see below.
Front/Rear Imbalance
Cause: Rear Air Bellows Leaks
Cold weather or overpressure can cause leaks in early build rear air bellows, causing the vehicle to settle to the bump stops when left at rest, inability to rise to normal height, or cause front/rear height imbalances. This problem can be caused by excessive pressure in the system leading to premature failure of the rear air bags. It is not clear why this excess pressure occured, but a service campaign was undertaken in April 2003 on vehicles 3A101029 to 3A106310 to address it by installing a second pressure relief valve (MAV500010K) in the spare tire compartment, in the feed line from the compressor to the air tank. (However, this valve in turn might cause its own problems -- see above). A second service campaign was initiated in January 2004 (for VIN numbers 3A101029 up to 4A156147) to replace the rear air springs with an improved design and also update the ECU software to get around the sticking pressure relief valve problem mentioned above.
In spite of these fixes, the rear spring bellows still seem to be more prone to leaking than the front. In May 2006 my May 2004 build RR III would sag in the rear after being parked overnight; the dealer found both rear bellows were leaking and had to be replaced.
EFI / Check engine light: 1990-1995 Range Rover Classic
Check engine light: 1994-5 Discovery
** Note: These vehicles have both a “Check Engine” light and a “Service Engine” light. Check engine means you have a problem. Service engine means it's been about 52,000 miles since the timer last reminded you to perform emission service. The information below pertains to Check Engine.
These fault codes will appear on a two digit display found under the passenger seat. Note that although the display can indicate fault codes up to 99 not all numbers are valid codes.
You read the codes by removing the side panel of the seat base (Range Rover) or looking at the display under the back of the seat (Discovery).
I have provided identification for each fault code. In many cases the text refers to test xx . These tests are found in the Land Rover Workshop Manual in the fuel injection section. Some fault codes point to a failed sensor, some indicate an engine fault that has caused the sensor to deliver an out-of-range signal, and some code may indicate either or both. Do not be too quick to replace parts on the basis of codes alone.
Here is how you clear codes once you've read them and addressed the faults:
- Switch ignition on.
- Disconnect serial link mating plug, wait 5 seconds, then reconnect.
- Switch ignition off and wait for main relay (located under the passenger seat in Range Rovers) to drop out.
- Switch ignition on. The display should now be reset. If there are other faults, the next one will be displayed. Otherwise the display will be black.
If there is more than one fault repeat these steps to clear each fault until the display is blank.
If you clear a code without performing a repair it (and the EFI light) may or may not return. Some codes are set by intermittent conditions that do not occur often. Other codes signal serious faults that are detected immediately upon startup.
On to the list of codes…
Nothing shown on display
Either nothing is wrong or the display is broken.
Code 02 - Power interruption
This code means power to the ECU has been disconnected and the truck has not yet been started. This code should go away as soon as the vehicle is started for the first time. Appearance of this code while driving may signal a problem within the ECU.
Code 12 - Airflow meter
Usually signals a problem with the airflow meter or the connector which can fall apart or become damaged. Refer to test 19, continuity test procedure.
Code 14 - Coolant sensor
Usually indicates a bad fuel injection coolant sensor. May also indicate a bad engine thermostat or a stuck viscous fan clutch. Refer to test 14, continuity test procedure.
Code 17 - Throttle potentiometer
Usually indicates a bad throttle position sensor. Refer to test 17, continuity test procedure.
Code 18 - Throttle potentiometer input high/airflow meter low
Usually indicates a problem with one of the two mentioned parts. Refer to tests 17, 18, and 19 of the continuity test procedure.
Code 19 - Throttle potentiometer input low/airflow meter high
Usually indicates a problem with one of the two mentioned parts. Refer to tests 17, 18, and 19 of the continuity test procedure.
Code 21 - Fuel tune select
Identifies that the tune select resistor is open circuit- refer to tune select resistor test. The tune resistor is embedded in the wire harness. This code may indicate damage to the wire harness.
Code 23 - Fuel supply
Check fuel system pressure, test 20 of continuity test procedure.
Code 25 - Ignition misfire
This code indicates that an ignition system misfire has been detected. Codes 40 or 50 indicate on which bank the misfire has occurred.
Code 28 - Air leak
One way to check for small leaks is by spraying choke cleaner at the joint you want to check while the motor is idling. A change in tone indicates the choke cleaner is being sucked into the engine. Check for air leaks in the following areas:
•Hose, air flow meter to plenum
•Breather system hoses to plenum
•Brake servo hose
•Vacuum reservoir hose (fresh air solenoid)
•Distributor vacuum advance
•Hose, purge valce to plenum
•Injector seals
•Joint - bypass air valve to plenum plenum chamber to ram housing ram housing to inlet manifold inlet manifold to cylinder head bypass air valve hose
Code 29 - ECU memory check
If this code appears all other faults are unreliable and must be ignored. Use the procedure below to clear the code and see if it re-appears. If it does, your ECU is almost certainly bad.
Procedure:
• leave battery connected
• switch ignition off
• wait for approximately 5 seconds
• disconnect ECU plug.
• reconnect ECU plug
• switch ignition on and check display unit.
If fault code 29 is detected again, swap out the ECU for another one and retest.
Code 34 - Injector bank A
The display will indicate if the injector(s) are causing the engine to run rich or lean.
If the bank is running rich, check for - faulty injector wiring and connectors, stuck open injectors.
If the bank is running lean, check for - faulty injector wiring and connectors, blocked injectors.
Code 36 - Injector bank B
As code 34, except relevant to bank A injectors.
Code 44 - Lambda sensor A - left bank
Code 45 - Lambda sensor B - right bank
If one of these fault codes (#44 or #45) is displayed check the wiring to that particular lambda sensor. In addition this fault will be displayed if the vehicle has a condition which causes it to run very lean or very rich on one side (example - a vacuum leak or a bad injector). This code often appears in conjunction with the misfire codes in cases of bad ignition misfire (cross-firing plug wires)
If both codes are displayed, the voltage supply to the heater coils of the sensors must be checked. Check for 12V appearing on the O2 signal lead, and check the heater circuit for shorts.
Code 48 - Stepper motor
Check base idle speed as follows:
• First remove and clean the idle motor and the port it screws into. Clean the throttle body as well.
• On the top of the throttle body you will see a hole (possibly covered by an anti tamper plug) for the base idle adjuster.
• Remove the air bypass hose from the throttle body, which will cause the engine to speed up to 2500rpm or so. Unplug the connector to the idle motor after 5 seconds then reconnect the hose.
• Squeeze the hose shut with needle nose vise grips and adjust the base idle using an allen wrench to give an idle speed of 6-700rpm. Get the lowest speed you can that gives smooth running and does not stall when blipping the throttle. Screw in for slower idle, out for faster idle.
• Reconnect the idle stepper and remove the vise grip and you should be done.
• In addition, refer to tests 15 and 16 of continuity test procedure. Check road speed sensor- refer to test 25 of continuity test procedure.
Code 40 - Misfire bank A - left bank
Code 50 - Misfire bank B - right bank
If one fault code 40 or 50 is displayed check components applicable to the particular bank that the misfire has occurred on:
•Spark plugs
•Ignition leads
•Distributor cap
•Injectors - if code 34 bank A or 36 bank B displayed
If both codes are displayed, check the following components common to both banks:
•Distributor cap
•Distributor rotor
•Coil and its associated connections
•Distributor pick-up (air gap)
•Amplifier
•Injectors (if code 34 or 36 is displayed)
Code 58 - Group faults 23/28
This indicates that a fault has been registered that is caused by the fuel supply or an air leak but the exact fault cannot be identified. Check all items outlined under codes 23 and 28.
Code 59 - Fuel thermistor
Refer to test 13 of the continuity test procedure.
Code 68 - Road speed sensor
refer to test 25 of continuity test procedure.
Code 69 Gearswitch
Refer to test 24 of continuity test procedure.
Code 88 - Purge valve leak
Refer to test 9 and 10 of the continuity test procedure.
1996 and newer Rovers
All 4.0SE and 4.6HSE and newer Range Rovers, and all 1996 and newer Discoveries use OBD II compatible diagnostics for the engine management system. OBD II is a diagnostic protocol supposedly shared by all carmakers as of the 1996 model year. Inexpensive scanners are available to read and reset OBD II codes. There appears to be some variability in OBD II scanner programming, so if you find a scanner that won't read codes from your newer Rover try another brand.
In our shop we read codes without difficulty using OTC and GenRad brand scanners. Many other brands work also. We have encountered problems with some Snap-On models. Note: most generic OBD II scanners cannot read fault codes from 1995 4.0SE models even though they have an OBD II connector.
Your scan tool should include a book of OBD II generic codes. The list of codes runs into the hundreds. for European standard OBD II codes.
Land Rover has made many other functions available at the OBD II connector but they are not accessible with generic scan tools. If you are looking for a shop to service a Rover one prerequisite should be possession of an Autologic or dealer T4 dedicated test system, which gives access to all the other vehicle computer systems.
Computer systems accessible only with the specialist Land Rover test system are:
- SRS - airbags
- ABS, ETC, HDC, TRACS - antilock brakes, hill descent control, and electronic traction control
- EAS - electronic air suspension
- ETC - electronic transmission control
*note that the transmission controller can set faults that turn on the "service engine" warning when no faults are present in the engine computer.
- ACC - automatic climate control
- SLABS - the integrated brake/suspension module on Discovery II
- BECM - the body control module
In addition, keys and alarm controllers can only be programmed with the specialist tools. |
