Isuzu KB P190. Manual - part 576

6E–134

ENGINE DRIVEABILITY AND EMISSIONS

10

Using the DVM and check the IAT sensor ground
circuit.

1. Ignition “On”, engine “Off”. 

2. Disconnect the IAT sensor connector. 

3. Check the circuit for short to power supply circuit. 

Was the DVM indicated specified value?

Less than 1V

Go to Step 11

Repair faulty 

harness and 

verify repair

11

Using the DVM and check the IAT sensor ground
circuit.
Breaker box is available: 

1. Ignition “Off”, engine “Off”. 

2. Install the breaker box as type A. (ECM

disconnected) Refer to 6E-88 page.

3. Disconnect the IAT sensor connector. 

4. Check the circuit for open circuit. 

Was the problem found?

Breaker box is not available: 

1. Ignition “Off”, engine “Off”. 

2. Disconnect the IAT sensor connector. 

3. Check the circuit for open circuit. 

Was the problem found?

—

Repair faulty 

harness and 

verify repair

Go to Step 14

12

Substitute a known good IAT sensor assembly and
recheck.
Was the problem solved?

—

Go to Step 13

Go to Step 14

13

Replace the IAT sensor assembly. 
Is the action complete?

—

Verify repair

—

14

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 15

Step

Action

Value(s)

Yes

No

V

C121

2

J2-1

Breaker Box

C-121

2

Ω

C56(J2)

C121

2

1

ENGINE DRIVEABILITY AND EMISSIONS

6E–135

15

Replace the ECM. 
Is the action complete? 
IMPORTANT:  The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure.

—

Verify repair

—

Step

Action

Value(s)

Yes

No

6E–136

ENGINE DRIVEABILITY AND EMISSIONS

DIAGNOSTIC TROUBLE CODE (DTC) P0117 ENGINE COOLANT 

TEMPERATURE SENSOR LOW INPUT

Condition for setting the DTC and action taken when the DTC sets

Circuit Description

The engine coolant temperature (ECT) sensor is a
thermistor mounted in the engine coolant stream. The
engine control module (ECM) applies a voltage (about 5
volts) through a pull-up resistor to the ECT signal circuit.
When the engine coolant is cold, the sensor (thermistor)
resistance is high, therefore the ECM will measure a
high signal voltage. As the engine coolant warms, the
sensor resistance becomes lower, and the ECT signal
voltage measured at the ECM drops. Diagnostic Trouble
code P0117 set when the ECM detects an excessively
low signal voltage on the engine coolant temperature
sensor signal circuit.

Diagnostic Aids

Check for the following conditions:

• Poor connection at ECM - Inspect harness

connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.

• Damaged harness - Inspect the wiring harness for

damage, short to ground, short to battery positive,
and open circuit. If the harness appears to be OK,
observe the ECT display on the Tech 2 while moving
connectors and wiring harnesses related to the ECT
sensor. A change in the ECT display will indicate the
location of the fault.

Code

Type

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

P0117

A

Engine Coolant Temperature Sensor 
Low Input

1. Engine run time is longer than 120 sec-

onds. 

2. ECT sensor output is more than 149 deg. 

C. 

The ECM uses default engine coolant 
temperature value based on intake air 
temperature and engine run time. 

ENGINE DRIVEABILITY AND EMISSIONS

6E–137

Diagnostic Trouble Code (DTC) P0117 

Engine Coolant Temperature Sensor Low Input

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go  to  Step 2

Go to On Board 

Diagnostic 

(OBD) System 

Check

2

1. Connect the Tech 2. 

2. Review and record the failure information. 

3. Select “F0: Read DTC Infor By Priority” in “F0:

Diagnostic Trouble Code”. 

Is the DTC P0117 stored as “Present Failure”?

—

Go to Step 3

Refer to 

Diagnostic Aids 

and Go to Step 

3

3

1. Using the Tech2, ignition “On” and engine “Off”. 

2. Select “Clear DTC Information” with the Tech2 and

clear the DTC information. 

3. Operate the vehicle and monitor the “F5: Failed

This Ignition” in “F2: DTC Information”.

Was the DTC P0117 stored in this ignition cycle?

—

Go to Step 4

Refer to 

Diagnostic Aids 

and Go to Step 

4

4

Check for poor/faulty connection at the ECT sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 5

5

Visually check the ECT sensor. 
Was the problem found? 

—

Go to Step 8

Go to Step 6

6

Using the DVM and check the ECT sensor.

1. Ignition “Off”,  engine “Off”. 

2. Disconnect ECT sensor connector. 

3. Measure the resistance of ECT sensor. 

Does the tester indicate standard resistance as shown
in the following table? 

Standard 

resistance

Go to Step 7

Go to Step 8

E60(J1)

E69

32

27

Temperature (°C)

Resistance (

Ω) (Approximately)

-20

26740

0

9120

20

3500

40

1464

60

664

80

333

100

175

120

102

2

1

ECT Sensor

Ω

1

2