Discovery 2. Manual - part 466

 

  Index      Land Rover     Land Rover Discovery 2 - service manual 1999 year

 

Search            

 

 

 

 

 

 

 

  

 

Content   ..  464  465  466  467   ..

 

 

Discovery 2. Manual - part 466

 

 

ENGINE MANAGEMENT SYSTEM - TD5

DESCRIPTION AND OPERATION

18-1-7

Engine Control Module (ECM)

The ECM is made from aluminium alloy and is located in the engine compartment on the RH side inner wing. The 
ECM has an interface of 72 pins via two connectors providing both input information and output control. The ECM 
receives information from the sensors to inform it of the current state of the engine. The ECM then refers this 
information to stored values in its memory and makes any changes to the operation of the engine as necessary via 
the actuators.  This is a rolling process and is called adaptive strategy.  By using this adaptive strategy the ECM is 
able to control the engine to give optimum driveability throughout all operating conditions. There is no ECM self test, 
although the ECM saves driveability data from the last journey. Power down of the ECM can take between 10 seconds 
and 10 minutes dependent on coolant temperature.

ENGINE MANAGEMENT SYSTEM - TD5

18-1-8

DESCRIPTION AND OPERATION

Input/Output
ECM inputs and outputs are detailed below:

Connector C0158

Pin No.

Input/Output

Function

Signal type

Value

Interfaces

A1

Output

Injector 5

Analogue

0

A2

Not used

A3

Output

EGR modulator

Digital

0-12

A4

Not used

A5

Input

FT sensor earth

0 volts

0

A6

Input

MAP sensor

Analogue

0-5 volts

A7

Input

ECT sensor

Analogue

0-5 volts

A8

Sensor supply

Sensor supply

5 volts

5 volts

A9

HT pin

A10

Input

AAP sensor

Analogue

0-5 volts

A11

Input

MAF sensor

Analogue

0-5 volts

A12

Not used

A13

Input

CKP sensor positive

Analogue

A14

Not used

A15

Input

Sensor earth 5

0 volts

0 volts

A16

Input

CKP sensor screened earth

0 volts

0 volts

A17

Input

Sensor earth 6

0 volts

0 volts

A18

Input

Sensor earth 3

0 volts

0 volts

A19

Input

FT sensor

Analogue

0-5 volts

A20

Input

Sensor earth 2

0 volts

0 volts

A21

Output

Turbocharger wastegate 
modulator

Digital

0-12 volts

A22

Output

Injector common 2

Analogue

0-85 volts

A23

Output

Injector common 1

Analogue

0-85 volts

A24

Output

Injector 4

Analogue

0 volts

A25

Output

Injector 1

Analogue

0 volts

A26

Output

Injector 2

Analogue

0 volts

A27

Output

Injector 3

Analogue

0 volts

A28

Not used

A29

Output

Glow plug relay

Analogue

0-90 volts

A30

Input

Sensor earth 4

0 volts

0 volts

A31

Not used

A32

Input/Output

CAN negative 

Digital

2.5-5 volts

EAT

A33

Input

High/low ratio switch

Digital

0-5 volts

EAT, SLABS

A34

Input

IAT sensor

Analogue

0-5 volts

A35

Input/Output

Can positive 

Digital

2.5-5 volts

EAT

A36

Input

CKP sensor negative

0 volts

0 volts

ENGINE MANAGEMENT SYSTEM - TD5

DESCRIPTION AND OPERATION

18-1-9

Connector C0658

Pin No.

Input/Output

Function

Signal type

Value

Interfaces

B1

Input

Earth 1

0 volts

0 volts

B2

Input

Earth 4

0 volts

0 volts

B3

Input

Supply battery voltage

12 volts

12 volts

B4

Output

Cooling fan relay

Switch

12-0 volts

A/C ECU

B5

Output

Fuel pump relay

Switch

12-0 volts

B6

Output

MIL

Switch

12-0 volts

Instruments

B7

Output

Temperature gauge

Digital

0-12 volts

Instruments

B8

Not used

B9

Input

A/C clutch request

Switch

12-0 volts

A/C ECU

B10

Input

Normally closed brake 
switch

Switch

12-0 volts

B11

Input

Cruise control SET+ switch

Switch

12-0 volts

B12

Input

TP sensor 1

Analogue

0- 5 volts

B13

Input

Vehicle speed

Digital

0-12 volts

B14

Input

TP sensor supply

5 volts

5 volts

B15

Input

Cruise control master switch

Switch

12-0 volts

B16

Input

Normally open brake switch

Switch

0-12 volts

B17

Input

Cruise control RES switch

Switch

12-0 volts

B18

Input/Output

Serial communication link

Digital

0-12 volts

All ECU's

B19

Output

Tachometer engine speed

Digital

0-12 volts

Instrument 
Cluster

B20

Not used

B21

Output

Main relay

Switch

0-12 volts

B22

Input

Supply battery voltage

12 volts

12 volts

B23

Input

A/C fan request

Switch

12-0 volts

B24

Input

Earth 3

0 volts

0 volt

B25

Input

Earth 2

0 volts

0 volts

B26

Input

TP sensor earth

0 volts

0 volts

B27

Input

Supply 2

12 volts

12 volts

B28

Not used

B29

Output

A/C relay

Switch

12-0 volts

B30

Output

Glow plug warning light

Switch

12-0 volts

Instrument 
Cluster

B31

Not used

B32

Output

ABS

digital

0-5 volts

SLABS

B33

Input

Ignition

Switch

0-12 volts

B34

Input

Security code

digital

0-5 volts

B35

Input

Clutch switch

Switch

12-0 volts

B36

Input

TP sensor 2

Analogue

5-0 volts

ENGINE MANAGEMENT SYSTEM - TD5

18-1-10 DESCRIPTION AND OPERATION

Mass Air Flow (MAF) sensor

The MAF sensor is located in the intake system between the air filter housing and the turbocharger. The ECM uses 
the information generated by the MAF to control exhaust gas recirculation (EGR).

The MAF sensor works on the hot film principal. The MAF sensor has 2 sensing elements contained within a film. One 
element is controlled at ambient temperature e.g. 25 

°

C (77 

°

F) while the other is heated to 200 

°

C (392 

°

F) above 

this temperature e.g. 225 

°

C (437 

°

F). As air passes through the MAF sensor the hot film will be cooled. The current 

required to keep the constant 200 

°

C (392 

°

F) difference provides a precise although non-linear signal of the air drawn 

into the engine. The MAF sensor sends a voltage between 0 and 5 volts to the ECM proportional to the mass of the 
incoming air. This calculation allows the ECM to set the EGR ratio for varying operating conditions.  

Input/Output
The MAF sensor receives battery voltage from the main relay in the engine compartment fuse box.  Signal output from 
the MAF sensor to the ECM is a variable voltage proportional to air drawn into the engine.

Input to the MAF sensor is via pin 5 of connector C0570 at the engine compartment fuse box.  This 12 volt supply is 
provided by the main relay via fuse 2 in the engine compartment fuse box. The MAF sensor receives the input voltage 
at pin 3 of the sensor connector.

Output from the MAF sensor is measured at pin 11 of the ECM connector C0158. The earth path is via pin 20 of the 
ECM connector C0158. 

The MAF sensor can fail the following ways or supply incorrect signal:

l

Sensor open circuit.

l

Short circuit to vehicle supply.

l

Short circuit to vehicle earth.

l

Contaminated sensor element.

l

Damaged sensor element.

l

Damaged in wiring harness. 

l

MAF supplies incorrect signal (due to air leak or air inlet restriction).

In the event of a MAF sensor signal failure any of the following symptoms may be observed:

l

During driving engine speed may dip, before recovering.

l

Difficult starting.

l

Engine stalls after starting.

l

Delayed throttle response.

l

EGR inoperative.

l

Reduced engine performance.

l

MAF signal out of parameters.

The MIL will not illuminate in a MAF sensor failure, and the ECM will use a fixed default value from its memory. 

 

 

 

 

 

 

 

Content   ..  464  465  466  467   ..