Discovery 2. Manual — part 81
ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-53
Function
With the ECM operating in the 'New' state, TestBook is required to instruct the ECM to learn the new BCU code. If the
ECM is in delivery state (i.e. direct from the supplier), it will not run the vehicle and will store a new ECM fault code
when it is fitted. This code must be cleared after instructing the ECM to learn the BCU code using TestBook.
When the ECM is in the 'Secure' state, no further action is required as the ECM has successfully learned the BCU
code. A 'Secure' ECM can not be configured to a 'No Code' state.
If the vehicle is fitted with an ECM with a valid code, the engine will start and the MIL will go out.
However, if the ECM has an invalid BCU security code the engine will crank, start, and then immediately stall. The
status of the security system can only be interrogated using TestBook.
TestBook is able to retrieve the following immobilisation fault codes:
Misfire detection
Due to increasing legislation, all new vehicles must be able to detect two specific levels of misfire.
Conditions
The ECM is able to carry out misfire detection as part of the OBD system using the following component parts:
l
Flywheel reluctor adaptation.
l
Calculation of engine roughness.
l
Detection of excess emissions misfire.
l
Detection of catalyst damaging misfire.
Function
The flywheel/ reluctor ring is divided into four segments 90
°
wide. The ECM misfire detection system uses information
generated by the CKP to determine crankshaft speed and position. If a misfire occurs, there will be an instantaneous
slight decrease in engine speed. The ECM misfire detection system is able to compare the length of time each 90
°
segment takes and is therefore able to pinpoint the source of the misfire.
For the ECM misfire detection system to be calibrated for the tolerances of the reluctor tooth positions, the flywheel/
reluctor ring must be 'adapted' as follows:
l
1800 - 3000 rev/min = speed range 1.
l
3000 - 3800 rev/min = speed range 2.
l
3800 - 4600 rev/min = speed range 3.
l
4600 - 5400 rev/min = speed range 4.
The ECM carries out flywheel/ reluctor ring adaptions across all the above speed ranges and can be monitored by
TestBook. The test should be carried out as follows:
l
Engine at normal operating temperature.
l
Select second gear (for both automatic and manual transmission vehicles).
l
Accelerate until engine rev limiter is operational.
l
Release throttle smoothly to allow engine to decelerate throughout the speed ranges.
l
Repeat process as necessary until all adaptations are complete.
P Code
J2012 Description
Land Rover Description
P1666
Engine anti-theft signal circuit malfunction
BCU serial link frame/ bit timing error
P1667
Engine anti-theft signal circuit low
Serial link short circuit to earth
P1668
Engine anti-theft signal circuit high
Serial link open circuit
P1672
Engine anti-theft signal circuit wrong code
received
Secure ECM, received incorrect code
P1673
Engine anti-theft signal new engine control
module not configured
New ECM fitted
P1674
Engine anti-theft signal
No code ECM, valid code received
ENGINE MANAGEMENT SYSTEM - V8
18-2-54 DESCRIPTION AND OPERATION
TestBook is able to retrieve the following misfire detection fault codes:
TestBook is able to retrieve the following Catalyst damage fault codes:
The flywheel/ reluctor ring adaptions must be reset if the CKP sensor or the flywheel are changed.
P Code
J2012 Description
Land Rover Description
P0300
Random/multiple cylinder misfire detected
Excess emissions level of misfire on more than one
cylinder
P0301
Cylinder 1 misfire detected
Excess emissions level of misfire detected on cylinder
No.1
P0302
Cylinder 2 misfire detected
Excess emissions level of misfire detected on cylinder
No.2
P0303
Cylinder 3 misfire detected
Excess emissions level of misfire detected on cylinder
No.3
P0304
Cylinder 4 misfire detected
Excess emissions level of misfire detected on cylinder
No.4
P0305
Cylinder 5 misfire detected
Excess emissions level of misfire detected on cylinder
No.5
P0306
Cylinder 6 misfire detected
Excess emissions level of misfire detected on cylinder
No.6
P0307
Cylinder 7 misfire detected
Excess emissions level of misfire detected on cylinder
No.7
P0308
Cylinder 8 misfire detected
Excess emissions level of misfire detected on cylinder
No.8
P Code
J2012 Description
Land Rover Description
P1300
Misfire detected sufficient to cause catalyst
damage
Catalyst damaging level of misfire on more than one
cylinder
P1301
No description
Catalyst damaging level of misfire detected on cylinder
No.1
P1302
No description
Catalyst damaging level of misfire detected on cylinder
No.2
P1303
No description
Catalyst damaging level of misfire detected on cylinder
No.3
P1304
No description
Catalyst damaging level of misfire detected on cylinder
No.4
P1305
No description
Catalyst damaging level of misfire detected on cylinder
No.5
P1306
No description
Catalyst damaging level of misfire detected on cylinder
No.6
P1307
No description
Catalyst damaging level of misfire detected on cylinder
No.7
P1308
No description
Catalyst damaging level of misfire detected on cylinder
No.8
ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-55
Vehicle Speed Signal (VSS)
The VSS is used, by the ECM, to control idle speed and overrun cut off. The ECM receives the signal through a hard
wired connection direct from the SLABS ECU.
For vehicles fitted with an automatic gearbox, two vehicle speed signals are received by the ECM. The second signal
is derived from the main gearbox output shaft speed, and is sent to the ECM by the Electronic Automatic Transmission
(EAT) ECU though the Controller Area Network (CAN). The ECM compares the vehicle speed signal generated by
the SLABS ECU with that supplied via the CAN.
The ECM also receives transfer box information. This allows the ECM to take in to account the vehicle being driven
using low range gearing and compensate as necessary.
On vehicles with manual transmission, the SLABS signal is checked against a threshold value stored in ECM memory.
If other engine parameters indicate the engine is at high load and the VSS is below the threshold, a fault condition is
registered in the diagnostic memory.
The vehicle speed signal generated by the SLABS ECU is in the form of a pulse width modulated signal (PWM).
Pulses are generated at 8000 per mile, and the frequency of the signal changes in accordance with road speed. At
zero road speed the ECU outputs a reference signal at a frequency of 2Hz for diagnostic purposes.
Function
The input signal for the SLABS ECU is measured via pin 22 of connector C0637 of the ECM. The SLABS ECU
generates a PWM signal switching between 0 and 12 volts at a frequency of 8000 pulses per mile. For vehicles with
automatic gearbox the input signal for the EAT ECU is measured via pins 36 and 37 of connector C0637 of the ECM.
These pin numbers provide a bi-directional communications link using the CAN data bus.
In the case of a VSS failure on vehicles with automatic gearboxes, the ECM applies default values derived from the
EAT ECU. There are no default values for manual gearbox vehicles.
The VSS can fail in the following ways:
l
Wiring short circuit to vehicle supply.
l
Wiring short circuit to vehicle earth.
l
Wiring open circuit.
In the event of a VSS failure, any of the following symptoms may be observed:
l
MIL illuminated after 2 driving cycles (NAS only).
l
Vehicle speed limiting disabled (manual transmission vehicles only).
l
SLABS/HDC warning lamp on and audible warning.
Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by
TestBook:
Rough road signal
When the vehicle travels across rough terrain, or on rough roads instability becomes evident in the drive train. The
ECM could interpret these vibrations as a 'false misfire'. To counteract this 'false misfire' the SLABS ECU generates
a rough road signal, sends it to the ECM so that the ECM can suspend misfire detection for as long as the vehicle is
travelling on the 'rough road'.
P Code
J2012 Description
Land Rover Description
P0500
Vehicle speed sensor malfunction
VSS short or open circuit
P0501
Vehicle speed sensor range/performance
VSS implausible
ENGINE MANAGEMENT SYSTEM - V8
18-2-56 DESCRIPTION AND OPERATION
Function
Input for the rough road signal is measured via pin 34 of connector C0637 of the ECM. The SLABS ECU generates
a PWM signal that varies in accordance with changing road conditions. The rough road PWM signal operates at a
frequency of 2.33 Hz
±
10%. The significance of changes in the PWM signal are shown in the following table:
The rough road signal can fail in the following ways:
l
Harness or connector damage
l
SLABS failure — wheel speed sensor
A rough road signal failure may be evident from the following:
l
HDC / ABS warning light on
Should a malfunction of the rough road signal occur, the following fault codes may be evident and can be retrieved
by TestBook:
Hill Descent Control (HDC) signal
The ECM transmits throttle angle, engine torque, engine identification (Td5 or V8), and transmission type (automatic
or manual) data to the SLABS ECU to support the Hill Descent Control system. The information is transmitted via a
0 – 12V pulse width modulated (PWM) signal at a frequency of 179.27 Hz.
Function
The HDC signal output from the ECM is via pin 29 of connector C0636. The ECM generates a PWM signal that varies
in pulse width in accordance with changing throttle angle or engine torque. The throttle angle data is transmitted on
pulses 1, 3, 5 and 37. The engine torque data is transmitted on pulses 2,4,6 and 38. The engine and transmission
information is transmitted on pulse 39. A synchronising pulse is transmitted after every 39th pulse.
The HDC signal can fail in the following ways:
l
Harness or connector damage
A HDC signal failure may be evident from the following:
l
HDC / ABS warning light on
l
HDC inoperative
l
Audible warning
Should a malfunction of the HDC signal occur, the following fault codes may be evident and can be retrieved by
TestBook:
PWM signal
Indication
<10%
Electrical short circuit to ground
25%
±
5 %
Smooth road
50%
±
5 %
SLABS error
75%
±
5%
Rough road
>90%
Electrical short circuit to battery voltage
P Code
J2012 Description
Land Rover Description
P1590
ABS rough road signal circuit malfunction
Hardware is OK, but SLABS ECU is sending an error
signal
P1591
ABS rough road signal circuit low
Signal from SLABS ECU short circuit to earth
P1592
ABS rough road signal circuit high
Signal from SLABS ECU short circuit to vehicle battery
supply
P Code
J2012 Description
Land Rover Description
P1663
Throttle angle/Torque signal circuit malfunction
SLABS HDC link open circuit
P1664
Throttle angle/Torque signal circuit low
SLABS HDC link short circuit to ground
P1665
Throttle angle/Torque signal circuit high
SLABS HDC link short circuit to battery voltage
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