landrover Workshop Repair Guides

Land Rover Workshop Service and Repair Manuals

Diagnostics > < Electronic Automatic Transmission (EAT) ECU|Page 204
Page 153
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AUTOMATIC GEARBOX - JATCO

44-36

DESCRIPTION AND OPERATION

Main Relay
The main relay is located in the engine compartment fusebox and supplies battery voltage to the EAT ECU, in addition 
to other vehicle components. The main relay is energised by the ECM when the ignition is switched on.

When the ignition is switched off, the ECM will maintain the main relay in an energised state for several minutes. This 
allows for cooling fan operation to continue after the engine has been switched off and allows other vehicle ECU's to 
remain active. The EAT ECU remains active for a short period after the ignition is switched off to allow EEPROM fault 
code data to be stored.

In the event of a main relay failure, any of the following symptoms may be observed:

l

The gearbox will be locked in 4th gear (limp home mode)

l

No CAN communications will be available.

38

Earth

Input

39

Fluid temperature sensor

Input

40

Not used

-

41

Sport / Manual hold switch

Input

42

Not used

-

43

Brake switch signal

Input

44

Not used

-

45

Selector 4th range switch

Input

46

Not used

-

47

Not used

-

48

Shift lock solenoid fault

Input

49

Cruise control engaged signal

Input

50

Shift lock solenoid earth

Input

51

Not used

-

52

Shift solenoid valve C

Output

53

Low clutch timing solenoid valve

Output

54

12V battery voltage from main relay

Input

Pin No.

Description

Input/Output

Diagnostics > < Electronic Automatic Transmission (EAT) ECU|Page 204