Description - engine management (ENGINE MANAGEMENT SYSTEM - V8) (page 14 of 43)

ENGINE MANAGEMENT SYSTEM - V8

DESCRIPTION AND OPERATION 18-2-19

Input/Output
The electrical input and output to and from the ECT sensor are reference voltage and sensor earth. The ECM provides 
the ECT sensor with a 5 volt reference via pin 22 of connector C0636 of the ECM, and earth via pin 21 of connector 
C0636 of the ECM. The normal operating parameters of the ECT sensor are as follows

Should the sensor fail the ECM has a back up strategy that uses a changing default value during warm up based on 
the signal from the inlet air temperature sensor. When the strategy default value reaches 60 

°

C (140 

°

F), the ECM 

implements a fixed default value of 85 

°

C (185 

°

F). It will also illuminate the MIL.

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

l

Sensor open circuit.

l

Short circuit to vehicle supply.

l

Short circuit to earth.

l

Incorrect mechanical fitting.

l

Signal fixed above 40 

°

C (140 

°

F) will not be detected.

l

Signal fixed below 40 

°

C (140 

°

F)  will be detected.

In the event of an ECT sensor signal failure any of the following symptoms may be observed:

l

Difficult cold start.

l

Difficult hot start.

l

Driveability concern.

l

MIL illuminated.

l

Instrument cluster temperature warning lamp illuminated.

l

Temperature gauge reads excessively hot.

l

Temperature gauge reads excessively cold.

l

Cooling fan will not run.

M124704A

0

20

40

60

80

100

120

140

160

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

V

k

Ω

k

Ω

V

°C

145

-5

0

-35

-2

0

-5

10

25

40

55

70

85

100

11

5

13

0