ENGINE MANAGEMENT SYSTEM - V8: DESCRIPTION AND OPERATION (page 9 of 12)

ENGINE MANAGEMENT SYSTEM - V8

DESCRIPTION AND OPERATION 18-2-57

Low fuel level signal
When the fuel level in the fuel tank becomes low enough to illuminate the low fuel level warning lamp in the instrument 
cluster, the instrument cluster generates a low fuel level signal. If the low fuel level signal is present during the ECM 
misfire detection function the ECM can use it to check for a 'false misfire'.

Conditions
The fuel sender generates the low fuel level signal when the fuel sender resistance is greater than 158 

±

 8 ohms.

Function
The illumination of the low fuel level warning lamp in the instrument cluster triggers the low fuel level signal to be sent 
to the ECM. This signal is processed via pin 8 of connector C0637 of the ECM.

Should a misfire occur while the fuel level is low, the following fault code may be evident and can be retrieved by 
TestBook.

Coolant temperature gauge signal
The ECM controls the temperature gauge in the instrument cluster. The ECM sends a coolant temperature signal to 
the temperature gauge in the instrument cluster in the form of a PWM square wave signal. 

The frequency of the signal determines the level of the temperature gauge. 

Conditions
The ECM operates the PWM signal under the following parameters:

l

-40 

°

C (-40 

°

F) = a pulse width of 768 

µ

s.

l

140 

°

C (284 

°

F) = a pulse width of 4848 

µ

s.

Function
The coolant temperature signal is an output from the ECM to the instrument cluster. The coolant temperature signal 
is generated via pin 44 of connector C0636 of the ECM.

The coolant temperature signal 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 coolant temperature signal failure any of the following symptoms may be observed:

l

Coolant temperature gauge will read cold at all times.

l

Coolant temperature warning lamp remains on at all times.

Controller Area Network (CAN) system
The controller area network (CAN) system is a high speed serial interface between the ECM and the Electronic 
Automatic Transmission (EAT) ECU. The CAN system uses a 'data bus' to transmit information messages between 
the ECM and the EAT ECU. Because there are only two components in this CAN system, one will transmit information 
messages and the other will receive information messages, and vice-versa.

P Code

J2012 Description

Land Rover Description

P1319

Misfire detected at low fuel level

Misfire detected with low fuel level