Classic RR etc EFI diagnostics
Preamble
The engine management systems fitted to Land Rover
OEM vehicles up to 1996 are of Lucas or Rover origin.
Overfinch etc used differing systems.
The Rover MEMS controls
from within the same control module.
primary ignition,
fuelling
idle functions
The Lucas 14CUX, (Also earlier Lucas 4CU,
Lucas13CU) controls
fuel injection
idle functions
and is a Bosch LH-jetronic compatible system
The Rover MEMS and Lucas14CUX have diagnostic
functions, the Lucas 4CU does not.
The 13CU was only used in some export markets.
The later electronic control modules have a
self-test capability that continually examines
the signals from certain engine sensors and
actuators, each signal is compared to a
table of pre-programmed values. If the diagnostic
software determines there is a fault present, the
ECM stores one or more fault codes in it's
memory. Codes are only stored for a limited range of
components.
The Lucas 14CUX generates 2-digit fault codes
for retrieval by a dedicated fault code reader.
The Rover MEMS does not generate fault code numbers
but displays faults on it's fault code reader screen,
without reference to a specific code number.
It is not possible to retrieve flashing light
codes from either the Lucas 14CUX system or from
the Rover MEMS.
Fault Code readers
The original was the Lucas Hand Held Tester which
required an interface unit, basically a level shifter
and possible firmware package which framed packets
according to ISO 9141 communications protocol
(not ISO 9141-2 thats OBDii new style RR etc.).
It also had podules to carry information about each
application and could be used on brakes and air
suspension. Lucas currently (Jan 2002) make a device which will
still read the 14CUX, it's considerably cheaper than
a test book too. (about 2-3,000 UKP)
After this came the Test Book from Rover (Franchised
dealers only), and latterly two aftermarket producers.
All three will set you back about 10,000 UKP. each!
LOS Limited operating strategy
Land Rover systems utilise LOS (or "limp-home mode").
When particular faults are identified, the ECM
implements LOS using programmed default values
rather than sensor signals. This allows the vehicle
to be driven to a test and repair site. Once
the fault is cleared, the ECM reverts to
normal operation.
Adaptive capability
Land Rover systems utilise an adaptive capability
that modifies the basic pre-programmed values
to take account of engine wear.
Diagnostic connector location
Lucas 14CUX
The connector is located either under
the driver's seat (early models) or behind the
driver's footwell kick-panel trim (later models)
(see illustrations Fig.1 and Fig.2) and can
only be used by a dedicated Fault Control Reader.
Fig.1 Location of Diagnostic connector and ECM -
Lucas 14CUX, early models
A dignostic connector B ECM
Fig.2 Location of Diagnostic connector and ECM
Lucas 14CUX, later models
A Diagnostic connector B ECM
Rover MEMS
The Diagnostic connector is located in the engine
compartment close to the ECM on the right-
hand wing. (see illustration Fig.3), and is
provided for use by a dedicated FCR alone.
Fig.3 Location of Diagnostic connector and ECM -
Rover MEMS
Retrieving fault codes
The only method of retrieving fault code;
from Lucas 14CUX and Rover MEMS is by
use of a dedicated Fault Code Reader.
Clearing fault codes
The only method of clearing fault codes
from Lucas 14CUX and Rover MEMS is by
use of a dedicated Fault Code Reader. In
particular the Rover MEMS employs non-volatile
memory, and codes will remain stored even
with the battery disconnected.
Fault Code Tables
Lucas 14CUX
FCR code Description
12 Mass airflow (MAF) sensor or MAF sensor circuit
14 Coolant temperature sensor (CTS) or CTS circuit
15 Fuel temperature sensor (FTS) or FTS circuit
17 Throttle pot sensor (TPS) or TPS circuit
18 Throttle pot sensor (TPS) or TPS circuit
19 Throttle pot sensor (TPS) or TPS circuit
21 Electronic control module (ECM) or ECM circuit (??queried)
25 Ignition misfire
28 Air leak
29 Electronic control module (ECM) memory check
34 Injector, bank A or injector circuit
36 Injector, bank B or injector circuit
40 Misfire, bank A or circuit
44 Oxygen sensor (OS) A or OS circuit (lambda sensor A)
45 Oxygen sensor (OS) B or OS circuit (lambda sensor B)
48 Idle air control valve (IACV) or IACV circuit
50 Misfire, bank B or circuit
59 Group fault - air leak or fuel supply
68 Vehicle speed sensor (VSS) or VSS circuit
69 Gear selector switch or circuit
88 Carbon filter solenoid valve (CFSV) or CFSV circuit
Rover MEMS
The Rover MEMS does not generate numerical fault codes. The
faults are displayed on the Fault Code Reader screen without
reference to a specific code number.
Faults in any of the following circuits or components will
cause a fault to be stored.
Circuits checked by Rover MEMS system
Airflow sensor
Carbon filter solenoid valve
CO resistor
Coolant temperature sensor (CTS) or CTS circui
Fuel pressure regulator
Fuel pump relay
Fuel temperature sensor
Idle speed stepper motor
Injector valves
Oxygen sensor (OS) or OS circuit
Throttle pot sensor (TPS) or TPS circuit
Vehicle speed sensor