Isuzu N-Series. Manual - part 428

6E-48 EMISSION AND ELECTRICAL DIAGNOSIS

Resistance value

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

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

Step

Action

Value

YES

NO

1

Was the “on-board diagnostic (OBD) system
check” performed?

—

Go to Step 2

Go to self diag 

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.

4. Observe the “Engine cool temp” display

on the scan tool.

Is the “Engine cool temp” at the specified
value?

120

°C

(248

°F)

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.

3. Observe the “Engine cool temp” display

on the scan tool.

Is the “Engine cool temp” at the specified
value?

120

°C

(248

°F)

Go to Step 5

Go to Step 6

4

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

Did any terminals require replacement?

—

Go to Step 8

Go to Step 10

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 7

Go to Step 10

EMISSION AND ELECTRICAL DIAGNOSIS 6E-49

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 7

Go to Step 10

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 9

Go to Step 10

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”

Is DTC 13 all right under Scan Tool Check?

—

Go to Step 11

Go to Step 2

11

Is any current trouble other than DTC 13 dis-
played by scan tool?

—

Go to trouble code 

section

Trouble code clear

Step

Action

Value

YES

NO

6E-50 EMISSION AND ELECTRICAL DIAGNOSIS

DTC-P14 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

N6A1163E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-51

Appearance of Water Temperature Sensor and
Connector Pin Assignment

Temperature Sensor

Connector Pin Assignment

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.

Legend

1. 3 pin connector
2. Engine coolant temperature sensor

N6A1160E

Legend

1. To ECT sensor
2. 3 pin gray

Connector No

Signal

1

Thermistor for engine

2

Thermistor for engine

3

Thermistor for meter

N6A1161E

Legend

1. Circuit tester

3. Engine coolant temperature sensor

2. Remove engine wire harness

4. Measure resistance between connector pin

N6A1162E