Jaguar XJ (X350). Manual — part 990

G549822t7 : CHECK THE ECT SENSOR RETURN CIRCUIT FOR HIGH
RESISTANCE

1. Key off. 2. Disconnect the ECT sensor connector, C34. 3. Key on, engine off. 4. Measure the

resistance between:

C34, harness side

Battery

Pin 02

Negative terminal

Is the resistance less than 10 ohms?

-> Yes

GO to Pinpoint Test G549822t8.

-> No

GO to Pinpoint Test G549822t4.

G549822t4 : CHECK THE ECT SENSOR RETURN CIRCUIT FOR SHORT CIRCUIT
TO POWER

1. Measure the resistance between:

C34, harness side

Battery

Pin 02

Positive terminal

Is the resistance geater than 100 Kohms?

-> Yes

GO to Pinpoint Test G549822t5.

-> No

GO to Pinpoint Test G549822t14.

G549822t5 : CHECK THE ECT SENSOR TO ECM RETURN CIRCUIT FOR HIGH
RESISTANCE

1. Key off. 2. Disconnect the ECM connector, C101. 3. Measure the resistance between:

C34, harness side C101, harness side

Pin 02

Pin E2

Is the resistance less than 10 ohms?

-> Yes

An intermittent fault may be present in the wiring harness. Visually check for chaffed wires or other

physical damage to the harness. If no fault is found in the circuit, suspect the following

component(s): - ECM connector - ECM

-> No

REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. Clear any

DTCs, test the system for normal operation.

G549822t8 : CHECK THE ECT SIGNAL CIRCUIT FOR SHORT CIRCUIT TO
GROUND

1. Measure the resistance between:

C34, harness side

Battery

Pin 01

Negative terminal

Is the resistance greater than 100 Kohms?

-> Yes

GO to Pinpoint Test G549822t9.

-> No

GO to Pinpoint Test G549822t12.

G549822t9 : CHECK THE ECT SIGNAL CIRCUIT FOR SHORT CIRCUIT TO
POWER

1. Measure the resistance between:

C34, harness side

Battery

Pin 01

Positive terminal

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Is the resistance greater than 100 Kohms?

-> Yes

GO to Pinpoint Test G549822t10.

-> No

GO to Pinpoint Test G549822t15.

G549822t10 : CHECK THE ECT SIGNAL CIRCUIT FOR HIGH RESISTANCE

1. Key off. 2. Disconnect the ECM connector, C101. 3. Measure the resistance between:

C34, harness side C101, harness side

Pin 01

Pin C2

Is the resistance less than 10 ohms?

-> Yes

GO to Pinpoint Test G549822t11.

-> No

REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. Clear any

DTCs, test the system for normal operation.

G549822t11 : CHECK THE COMPONENT RESISTANCE

1. Measure the resistance between:

C34, component side C34, component side

Pin 01

Pin 02

Is the resistance between 1 - 500 Kohms?

-> Yes

An intermittent fault may be present in the wiring harness. Visually check for chaffed wires or other

physical damage to the harness. If no fault is found in the circuit, suspect the following

component(s): - ECT connector - ECT sensor - ECM connector - ECM

-> No

INSTALL a new ECT sensor.

Engine Coolant Temperature (ECT) Sensor (18.30.10) Clear any DTCs, test the system for normal

operation.

G549822t12 : CHECK THE ECT SIGNAL AND RETURN CIRCUITS FOR SHORT
CIRCUIT TO EACH OTHER

1. Key off. 2. Disconnect the ECM connector, C101. 3. Key on, engine off. 4. Measure the resistance

between:

C34, harness side C34, harness side

Pin 01

Pin 02

Is the resistance greater than 100 Kohms?

-> Yes

GO to Pinpoint Test G549822t13.

-> No

REPAIR the short circuit. For additional information, refer to the wiring diagrams. Clear any DTCs, test

the system for normal operation.

G549822t13 : CHECK WHETHER THE SHORT CIRCUIT TO GROUND IS IN THE
HARNESS OR THE MODULE

1. Measure the resistance between:

C34, harness side

Battery

Pin 01

Negative terminal

Is the resistance greater than 100 Kohms?

-> Yes

Suspect: - ECM

-> No

REPAIR the short circuit. For additional information, refer to the wiring diagrams. Clear any DTCs, test

the system for normal operation.

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