Isuzu N-Series. Manual - part 458

6E-168 EMISSION AND ELECTRICAL DIAGNOSIS

Measure Resistance at Engine Coolant Temperature (ECT) Sensor

Caution:
When measuring resistance with a circuit tester, be careful not to damage or deform the terminals.

Resistance value

Notice:
Resistance value is difference according to the temperature of temperature sensor.

Connector No

Signal

1

Thermistor for engine 

2

Thermistor for engine

3

Thermistor for meter

Legend

1. Circuit tester

3. Engine coolant temperature sensor

2. Remove engine wire harness

4. Measure resistance between connector pin

Inspection Point

Resistance 

Value

Temperature 

on sensor

Reference

Connector

Pin No.

3 pin Black

1 

←→ 3

∞

—

Thermistor for ENGINE 

←→ Thermistor for meter

1 

←→ 2

2.5 (k

Ω)

20

°C (68°F)

Thermistor for ENGINE

247 (

Ω)

90

°C (194°F)

1 

←→ Body

∞

—

Thermistor for ENGINE 

←→ Body

2 

←→ 3

∞

—

Thermistor for ENGINE 

←→ Thermistor for meter

3 

←→ Body

146.6 (

Ω)

60

°C (140°F) Thermistor for meter ENGINE

2 

←→ Body

∞

—

Thermistor for ECM 

←→ Body

N6A1162E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-169

Step

Action

Value

YES

NO

1

Was the “Diagnostic system check” per-
formed?

—

Go to Step 2

Go to self diagnos-

tic system check

2

1. Ignition “OFF”
2. Disconnect the ECT sensor electrical con-

nector.

3. Jumper the ECT sensor signal circuit and

the ECT sensor ground circuit together at
the ECT sensor harness connector.

Does indicate DTC 13?

—

Go to Step 4

Go to Step 3

3

1. Ignition “OFF”
2. Jumper the ECT signal circuit at the ECT

sensor harness connector to chassis
ground.

Does indicate DTC 13?

—

Go to Step 5

Go to Step 6

4

Check four poor connection at the ECT sensor
and replace terminals if necessary.

Did any terminals require replacement?

—

Go to Step 10

Go to Step 8

5

1. Ignition “OFF”.
2. Disconnect the ECM, and check the ECT

sensor ground circuit for an open.

3. If the ECT sensor ground circuit is open,

repair it as necessary.

Was the ECT sensor ground circuit open?

—

Go to Step 10

Go to Step 7

6

1. Ignition “OFF”.
2. Disconnect the ECM, and check the ECT

sensor signal circuit for an open.

3. If the ECT signal circuit is open, repair it

as necessary.

Was the ECT sensor signal circuit open?

—

Go to Step 10

Go to Step 7

7

Check for poor sensor ground or ECT sensor
signal circuit terminal connection at the ECU
and replace terminal(s) if necessary.

Did any of the terminals need to be replaced?

—

Go to Step 10

Go to Step 9

8

1. Ignition “OFF”
2. Replace the ECT Sensor.

Is the action complete?

—

Go to Step 10

—

9

1. Replace the ECM.

Is the action complete?

—

Go to Step 10

—

10

1. Reconnect all the connectors removed.
2. Ignition “ON”, Engine “OFF”

Does DTC 13 come normal condition?

—

Go to Step 11

Go to Step 2

11

Is any current trouble other than DTC 13 dis-
played by indicator light?

—

Go to trouble code 

section

Trouble code clear

6E-170 EMISSION AND ELECTRICAL DIAGNOSIS

DTC-14 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

Appearance of Water Temperature Sensor and
Connector Pin Assignment

Temperature Sensor

Connector Pin Assignment

N6A1315E

Legend

1. 3 pin connector
2. Engine coolant temperature sensor

N6A1160E

Legend

1. To ECT sensor
2. 3 pin gray

N6A1161E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-171

Measure Resistance at Engine Coolant Temperature (ECT) Sensor

Caution:
When measuring resistance with a circuit tester, be careful not to damage or deform the terminals.

Resistance value

Notice:
Resistance value is difference according to the temperature of temperature sensor.

Connector No

Signal

1

Thermistor for engine

2

Thermistor for engine

3

Thermistor for meter

Legend

1. Circuit tester

3. Engine coolant temperature sensor

2. Remove engine wire harness

4. Measure resistance between connector pin

Inspection Point

Resistance 

Value

Temperature 

on sensor

Reference

Connector

Pin No.

3 pin Black

1 

←→ 3

∞

—

Thermistor for ENGINE 

←→ Thermistor for meter

1 

←→ 2

2.5 (k

Ω)

20

°C (68°F)

Thermistor for ENGINE

247 (

Ω)

90

°C (194°F)

1 

←→ Body

∞

—

Thermistor for ENGINE 

←→ Body

2 

←→ 3

∞

—

Thermistor for ENGINE 

←→ Thermistor for meter

3 

←→ Body

146.6 (

Ω)

60

°C (140°F) Thermistor for meter ENGINE

2 

←→ Body

∞

—

Thermistor for ECM 

←→ Body

N6A1162E