Range Rover Automatic Transmission. Manual — part 12

System Information Document

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4 Fault finding

If there is a fault with the transmission, a substitute function will be activated which will allow the vehicle to be driven in
some manner whilst attempting to protect the transmission. Depending on the fault, the substitute function activated may or
may not be noticeable to the driver.

Abnormal gear shifting

If a fault exists that will not damage the transmission, cause inconvienience to the driver or increase the emmisions output of
the vehicle by 15%, there will be no warning lights illuminated but a fault code will be stored. If a driver does notice the
vehicle is behaiving differently, this could be due to a fault of this type.

Sport and Manual lights flashing together

If something has happend which will effect the performance of the transmission, the Sport and Manual lights will flash at the
same time. This indicates a fault code has been stored. If this happens to a customer, the first thing the customer should
attempt is to turn off the ignition, and re-start the vehicle. If the lights continue to flash, the car should be taken to the nearest
Land Rover dealer as soon as possible.

If both lights are flashing, the transmission will have selected a limp-home mode. Although the vehicle will drive, damage to
the transmission may occur if the fault is not corrected. When the vehicle is in this state, special care should be taken when
selecting position D. In absolutly no circumstances should the vehicle be moving backwards when position D is selected.

4.1 Fixing faults

If either of the above conditions are true, the transmission controller should have stored a fault code. The following is
recommended as the order in which abnormal transmission beaviour should be investigated.

4.1.1 The transmission ECU is disconnected

The automatic transmission ECU is located under the left hand from seat of 98MY and later Discovery vehicles. On vehicles
prior to this model year, the transmission is hydraulic and therefore has no controlling electronics.

If the ECU has been disconnected, the transmission will have selected a hydraulic limp-home. The ECU should be connected
whilst the ignition is off.

4.1.2 The transmission has diagnosed a fault.

If the software within the transmission ECU has diagnosed there is something wrong with the system, a fault code will be
stored. If the diagnosed fault is currently active (ie, the transmission can currently not fucntion correctly), the Sport and
Manual lights will flash together. After a fault code has been stored and the car has completed 40 journeys and the fault has
not happend again, the fault code will be deleted from memory.

If a fault is stored, the vehicle must be interogatted using a TestBook. The following page lists each fault code and its effect
on the transmission system.

4.1.3 Power to the ECU has been lost or K line not connected.

If the transmission ECU is connected, but the TestBook cannot communicate with the ECU, then the power supply to the ECU
may have been lost or the K line is not connected. In this instance, the following sequence of events should be followed.

A)

Turn the ignition to the off position.

B)

Disconnect the transmission ECU.

C)

Test the voltage at Pin 26 with a volt meter. This should read greater than 10V.

D)

Measure the resistance to ground with a digital volt meter or equivalent, of pins: 6 and 28. The resistance
should be less than 100 ohms.

E)

Turn the ignition to position II (normal running position).

F)

Test the voltage at Pin 54 with a volt meter. This should read greater than 10V.

If the above is completed with no strange reading, the ECU’s power supply is OK. The only possibility is the Diagnostic
connector is not attached to the ECU. To check for this:

G)

Measure the resistance between pin 31 of the ECU connector, and pin 7 of the vehicle diagnostic connector
(see drawing later). This should be less than 10 ohms.

System Information Document

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Page 20 of 52

4.2 MIL light illumination (N.A.S. vehicles only)

The illumination of the MIL (Check engine light) is controlled by the following counter. This counter is only applicable for
MIL (emissions) related faults. Any faults which prevent the gearbox from requesting the MIL light will automatically
illuminate the MIL light immediately.

Definition of a Warmup: Engine Coolant temperature rises by 16ºC and exceeds 72ºC.

1 s t d c ; c r a n k i n g d e t e c t e d ;
f a u l t p r e s e n t

2 n d d c ; c r a n k i n g d e t e c t e d

2 n d d c ; e n g i n e r u n n i n g ;
f a u l t n o t p r e s e n t

c r a n k i n g d e t e c t e d ;
f a u l t n o t p r e s e n t

6 4

6 3

6 1

6 2

4 0

3 9

0 0

5 9

5 8

5 7

5 6

5 5

5 4

5 3

5 2

w a r m u p d e t e c t e d ;
f a u l t n o t p r e s e n t

w a r m u p d e t e c t e d ;
f a u l t n o t p r e s e n t

e n g in e r u n n in g ; f a u l t p r e s e n t

e n g in e r u n n in g ; f a u l t p r e s e n t

f a u l t n o t p r e s e n t

1 s t d c ; c r a n k i n g d e t e c t e d ;
f a u l t n o t p r e s e n t

1 s t d c ; e n g i n e r u n n i n g ;
f a u l t n o t p r e s e n t

2 n d d c ; c r a n k i n g d e t e c t e d ;
f a u l t n o t p r e s e n t

2 n d d c ; e n g i n e r u n n i n g ;
f a u l t n o t p r e s e n t

3 r d d c ; c r a n k i n g d e t e c t e d ;
f a u l t n o t p r e s e n t

3 r d d c ; e n g i n e r u n n i n g ;
f a u l t n o t p r e s e n t

f a u l t p r e s e n t

f a u l t p r e s e n t

f a u l t p r e s e n t

f a u l t p r e s e n t

f a u l t p r e s e n t

f a u l t p r e s e n t

f a u l t p r e s e n t

f a u l t p r e s e n t

c r a n k i n g d e t e c t e d ;
M I L a f t e r 2 . d c

i g n i t i o n o n ; M I L
a f t e r 2 . d c

M I L o n im m e d i a t e l y ( s e e a b o v e )

f a u l t p r e s e n t

f a u l t p r e s e n t

c r a n k i n g d e t e c t e d

M I L O F F

M I L O N

f a u l t c o d e d e l e t e d

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5 Fault codes

5.1 Ambient conditions stored

The following lists all fault codes, together with the associated CARB P code, a description and the ambient conditions saved
with each fault code. The ambient conditions must be multiplied by the following conversion factors in order to calculate the
ambient conditions present when the fault was diagnosed.

Please note. The ambient conditions stored with each fault are those at the time of the first occurrence of the fault and are not
updated if the fault re-occurs. The ambient conditions stored with each fault may change prior to volume. This will not effect
TestBook, as the ambient conditions of each fault are referenced in the diagnostic protocol.

Variable

Scaling factor

Description

AN6

1 Volt = 4.65

10

Solenoid valve 1 voltage

AN7

1 Volt = 4.65

10

Solenoid valve 2 voltage

AN8

1 Volt = 4.65

10

Solenoid valve 3 voltage

AN9

1 Volt = 4.65

10

MES1 voltage

AN11

1 Volt = 4.65

10

MES2 voltage

MMM

2 Nm = 1

10

Engine torque

N_MOT

32 rpm = 1

10

Engine speed

UBATT

1 Volt = 9.8

10

Battery voltage

VGT_$X

1 km/h = 1

10

Output shaft speed

YPO_Old

L1=Bit 0, L2 = Bit 1 etc

Position switch L1 - L4 inputs

5.2 Fault codes descriptions

For the recommended method to diagnose each of the fault codes, please refer to the last section in this document, Fault tree
analysis.

Fault

Description

CARB

Ambient 1

Ambient 2

Ambient 3

1

Transmission relay control (Relay sticks, short circuit)

P1613

AN6

AN7

UBATT

The transmission controllers supply to the power outputs is faulty. This could be due to a problem in the harness (short circuit
to 12V of a power output stage), or an internal ECU fault.

Diagnostic operates:

Initialisation; approximately 60ms after ignition is switched on.
Normal operation;

Conditions to be met to run Diagnostic:

None

Time between fault present & fault stored:

10ms max

Variables used by the diagnostic:

Status of Watchdog circuit, Status of Highside switch

Will limp home mode be selected:

Yes

Conditions to be met to clear the fault:

Ignition to be switch on whilst fault not present, engine cranked.

Fault

Description

CARB

Ambient 1

Ambient 2

Ambient 3

2

Transmission relay control (Relay sticks, open circuit)

P1612

AN6

AN7

UBATT

The transmission controllers supply to the power outputs is faultly. This could be due to a problem in the harness (short
circuit to 0V), or and internal ECU fault.

Diagnostic operates:

Initialisation; approximately 200ms after ignition is switched on

Conditions to be met to run Diagnostic:

Battery voltage > 10.5V

Time between fault present & fault stored:

60ms max.

Variables used by the diagnostic:

Status of Watchdog circuit, Status of Highside switch

Will limp home mode be selected:

Yes

Conditions to be met to clear the fault:

Ignition to be switched on whilst fault not present, engine cranked.

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Fault

Description

CARB

Ambient 1

Ambient 2

Ambient 3

3

EEPROM communication fault

P1606

N_MOT

VGT_$X

MMM

The ECU cannot communicate with part of its internal memory, ie ECU fault

Diagnostic operates:

Continuously

Conditions to be met to run Diagnostic:

None

Time between fault present & fault stored:

1 second

Variables used by the diagnostic:

Internal communication between the Processor and the memory

Will limp home mode be selected:

Yes

Conditions to be met to clear the fault:

Ignition to be switched on whilst fault not present, engine cranked.

Fault

Description

CARB

Ambient 1

Ambient 2

Ambient 3

4

EEPROM checksum fault

P1601

N_MOT

VGT_$X

MMM

The software within the transmission control unit is not recognised. Part of the software is programmed to recognised if any
changes to the software or calibration have been made. If this is the case, the transmission will select limphome.

Diagnostic operates:

Normal operation

Conditions to be met to run Diagnostic:

Initialisation complete

Time between fault present & fault stored:

Max. 1 minute.

Variables used by the diagnostic:

Function of all data stored on EPROM

Will limp home mode be selected:

Yes

Conditions to be met to clear the fault:

Ignition switched on whilst fault not present, engine cranked

Fault

Description

CARB

Ambient 1

Ambient 2

Ambient 3

5

Torque converter lock-up clutch monitoring

P0741

N_MOT

VGT_$X

MMM

The software has detected a potential problem with the torque converter system.

Diagnostic operates:

When the Torque converter is locked

Conditions to be met to run Diagnostic:

No Engine speed, Output shaft speed or gear ratio faults active.

Time between fault present & fault stored:

5 seconds max.

Variables used by the diagnostic:

Engine Speed, Output shaft speed, Throttle angle, selected gear.

Will limp home mode be selected:

Yes

Conditions to be met to clear the fault:

Ignition switched on whilst fault not present, engine cranked

Fault

Description

CARB

Ambient 1

Ambient 2

Ambient 3

6

Watchdog check

P1606

N_MOT

VGT_$X

MMM

Internal ECU fault.

Diagnostic operates:

Initialisation; approximately 70ms after ignition on.
Normal operation;

Conditions to be met to run Diagnostic:

None

Time between fault present & fault stored:

60ms max.

Variables used by the diagnostic:

Status of Highside switch, Status of Watchdog circuit.

Will limp home mode be selected:

Yes

Conditions to be met to clear the fault:

Ignition switched on whilst fault not present, engine cranked