2002 ISUZU AXIOM sensor

6E±158
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0118 ECT Sensor Circuit High Voltage
060R200053
Circuit Description
The engine coolant temperature (ECT) sensor is a
thermistor mounted in on a coolant crossover pipe at the
front of the engine. The powertrain control module (PCM)
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
PCM will measure a high signal voltage. As the engine
coolant warms, the sensor resistance becomes less, and
the ECT signal voltage measured at the PCM drops. With
a fully warmed-up engine, the ECT signal voltage should
measure about 1.5 to 2.0 volts.
Conditions for Setting the DTC

Engine running time is longer than 90 seconds.

The ECT sensor signal indicates an engine coolant
temperature of ±39
C (±38
F) or less (about 5 volts)
for a total of 50 seconds over a 100-second period.
Action Taken When the DTC Sets

The PCM will ON the MIL after second trip with
detected fault.

The PCM will substitute the ECT reading with a default
engine coolant temperature value. The default value
is based on start-up intake air temperature and running
time.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

The PCM will turn the MIL ªOFFº on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.

A history DTC P0118 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0118 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
The ECT shares a ground with the Transmission Fluid
Temperature sensor, the Fuel Tank Pressure sensor, and
the MAP sensor.
Check the ground if these DTCs are also set.

Poor connection at PCM ± 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. 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.
If DTC P0118 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
If it is determined that the DTC occurs intermittently,

6E±159
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
performing the DTC P1115 Diagnostic Chart may isolate
the cause of the fault.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Verifies that the fault is present.
3. If DTC P0118 can be repeated only by duplicating
the Failure Records conditions, refer to the
ªTemperature vs. Resistance Valueº table. The
table may be used to test the ECT sensor at various
temperatures to evaluate the possibility of a
ªshiftedº sensor that may be shorted above or below
a certain temperature. If this is the case, replace
the ECT sensor. If the ECT sensor appears to be
OK, the fault is intermittent; refer to
Diagnostic Aids.
Engine Coolant Temperature Sensor

C
FOHMS
Temperature vs. Resistance Values
(approximate)
100212177
80176332
60140667
4511 31188
35951802
25772796
15594450
5417280
±52312300
±15521450
±30±2252700
±40±40100700
DTC P0118 ± ECT Sensor Circuit High Voltage

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªONº, engine ªOFFº.
2. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº below the specified value?
±39
C
(±38
F)
Go to Step 4Go to Step 3
31. Ignition ªONº, engine ªOFFº.
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor the ªDTCº info for DTC
P0118.
Does the Tech 2 indicate DTC P0118 failed?
Ð
Refer to Test
Description
Refer to
Diagnostic
Aids
41. Disconnect the ECT sensor electrical connector.
2. Jumper the ECT signal circuit and the sensor
ground circuit together at the ECT sensor harness
connector.
3. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº at the specified value?
140
C
(284
F)
Go to Step 6Go to Step 5
51. Jumper the ECT signal circuit at the ECT sensor
harness connector to chassis ground.
2. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº at the specified value?
140
C
(284
F)
Go to Step 7Go to Step 8
6Check for poor connections at the ECT sensor and
replace terminals if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 10

6E±160
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0118 ± ECT Sensor Circuit High Voltage

 
StepNo Ye s Value(s) Action
71. Ignition ªOFFº.
2. Disconnect the PCM, 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?
ÐVerify repairGo to Step 9
81. Ignition ªOFFº.
2. Disconnect the PCM, and check the ECT signal
circuit for an open.
3. If the ECT sensor signal circuit is open, repair it as
necessary.
Was the ECT signal circuit open?
ÐVerify repairGo to Step 9
9Check for a poor sensor ground or ECT signal circuit
terminal connection at the PCM and replace
terminal(s) if necessary.
Did any of the terminals need to be replaced?
ÐVerify repairGo to Step 11
10Replace the ECT sensor.
Is the action complete?
ÐVerify repairÐ
11Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±161
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0125 ECT Excessive Time to Closed Loop Fuel Control
060R200053
Circuit Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a ªclosed loopº
air/fuel metering system is used. When the vehicle is first
started, the powertrain control module (PCM) controls
fuel delivery in ªopen loopº, ignoring the heated oxygen
sensor (HO2S) signals and calculating air/fuel ratio based
on inputs from the engine coolant temperature, throttle
position, and mass air flow sensors. The PCM will begin
using the Bank 1 HO2S 1 and Bank 2 HO2S 1 signals for
controlling fuel delivery under ªclosed loopº conditions
when the following conditions have been met:

The HO2S output signals are varying, indicating that
the sensors are hot enough to operate properly.

The engine coolant temperature sensor indicates
coolant temperature above 50
C (122
F).

Time since start-up is at least 16 seconds for a warm
engine or 23 seconds for a cold engine.
Conditions for Setting the DTC

No active IAT, MAF or ECT DTC(s) are present.

Engine is running.

Vehicle speed is greater than 5 mph (8 km/h) .

Intake air temperature is greater than ±10
C (14
F)
0
C (32
F).

Start±up engine coolant temperature is between
±10
C (±14
F) and 28
C (82
F).
For a warm engine (intake air temperature is greater
than 10
C/50
F), engine coolant temperature
sufficient to allow ªclosed loopº operation
(50
C/122
F) is not achieved within 2 minutes of
start-up. For a cold engine (intake air temperature
between (±7
C and 10
C), engine coolant
temperature sufficient to allow ªclosed loopº operation
(50
C/122
F) is not achieved within 10 minutes of
start-up.

The above condition fails 20 consecutive times.
Action Taken When the DTC Sets

The PCM will ON the MIL after second trip with
detected fault.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

The PCM will turn the MIL ªOFFº on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.

A history DTC P0125 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0125 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.

6E±162
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
DTC P0125 set indicates a faulty ECT sensor.
Comparing the engine coolant temperature displayed on
a Tech 2 with actual coolant temperature measured with a
thermometer may isolate this condition. If the displayed
engine coolant temperature is not close to the actual
coolant temperature, replace the ECT sensor.
Check for the following conditions:

Poor connection at PCM ± 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. If the harness appears to be OK, observe the
display on the Tech 2 while moving connectors and
wiring harnesses related to the sensor. A change in the
display will indicate the location of the fault.
If DTC P0125 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage wince the DTC was last set.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Comparing the engine coolant temperature displayed
on a Tech 2 with actual coolant temperature
measured with a thermometer may isolate this
condition. If the displayed engine coolant
temperature is not close to the actual coolant
temperature, replace the ECT sensor. If the
temperatures are close, the fault is intermittent;
refer to
Diagnostic Aids.
Engine Coolant Temperature

C
FOHMS
Temperature vs. Resistance Values
(approximate)
100212177
80176332
60140667
4511 31188
35951802
25772796
15594450
5417280
±52312300
±15521450
±30±2252700
±40±40100700
DTC P0125 ±ECT Excessive Time to Closed Loop Fuel Control

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any ECT sensor DTCs set?
Ð
Go to
applicable
ECT sensor
DTC chart
Go to Step 3
31. Allow the engine to cool completely.
2. Check the cooling system coolant level (refer to
Cooling and Radiator).
Is the coolant level OK?
ÐGo to Step 4Go to Step 9
41. Start the engine.
2. With the engine idling, monitor ªENG COOL TEMPº
display on the Tech 2.
Does ªENG COOL TEMPº increase to above the
specified value within 2 minutes?
21
C (70
F)
Refer to
Diagnostic
Aids
Go to Step 5
5Check for proper operation of the thermostat (refer to
Cooling and Radiator).
Is the thermostat operating correctly?
ÐGo to Step 6Go to Step 9

6E±163
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0125 ±ECT Excessive Time to Closed Loop Fuel Control

 
StepNo Ye s Value(s) Action
6Compare engine coolant temperature displayed on the
Tech 2 to the actual coolant temperature measured
with a thermometer. (Observe normal precautions
when opening the cooling system.)
Is the Tech 2 engine coolant temperature indication
close to the measured temperature?
ÐGo to Step 9Go to Step 7
71. Ignition ªOFFº.
2. Disconnect the PCM.
3. Using a DVM, measure the resistance of the ECT at
the PCM connector.
4. Compare the DVM reading with the chart in ªTest
Descriptionº.
Is the chart value approximately equal to the
thermometer reading?
ÐGo to Step 12Go to Step 8
8Check for high resistance in wiring related to the ECT
sensor. Also, check for poor connections at the ECT
sensor and the PCM.
Was a problem found?
ÐGo to Step 10Go to Step 11
9Refer to Cooling and Radiator for cooling system
diagnosis and repair condition as necessary.
Is the action complete?
ÐVerify repairÐ
10Replace the faulty terminal(s) or repair faulty wiring as
necessary.
Is the action complete?
ÐVerify repairÐ
11Replace the ECT sensor.
Is the action complete?
ÐVerify repairÐ
12Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±164
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code(DTC)
P0128 Thermostat Insufficient Temperature for Stable Operation
060R200053
Circuit Description

The engine coolant temperature (ECT) sensor
thermistor mounted on a coolant crossover pipe at the
front of the engine.
This code determines if system has insufficient
coolant temperatures for stable operation.
Conditions for setting the DTC

Engine running.

No IAT, ECT and MAF DTCs set.

No VSS DTC set.
Warm case(Ambient temperature is between 50
F and
128
F.):

Time for coolant to reach stabilized closed loop value
is less than 239 sec.
Cold case(Ambient temperature is between 20
F and
50
F.):

Time for coolant to reach stabilized thermostat
regulation temperature is more than 263 sec.
Action Taken When the DTC Sets

The PCM will ON the MIL after second trip with
detected fault.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

The PCM will turn the MIL ªOFFº on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.

A history DTC P0128 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

DTC P0128 can be cleared using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Tech 2 ªClear Infoº function or by disconnecting the
PCM battery feed.
Diagnostic Aids
An intermittent may be caused by the following:

Poor connections.

Misrouted harness.

Rubbed through wire insulation.

Broken wire inside the insulation.
Check for the following conditions:

Poor connection at PCM±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.

6E±165
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
If the harness appears to be OK, observe the ECT
display on the Tech2 while moving connectors and
wiring harnesses related to the sensor.
A change in the display will indicate the location of
the fault.
If DTC P0128 cannot be duplicated, the information
included in the Failure Records data can be useful indetermined vehicle mileage since the DTC was last
set.
If it is determined that the DTC occurs intermittently,
performing the DTC P0128 Diagnostic Chart may
isolate the cause of the fault.
Diagnostic Trouble Code (DTC)
P0128 Thermostat Insufficient Temperature for stable operation

StepActionValue(s)Ye sNo
1Was the ªOn-Board(OBD)System Checkº performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Visually/physically check air duct and water pipe for
splits, kinks, and proper connections and routing.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 3
31. Remove and check the Thermostat for stable
operation. Refer to
6B section.
2. Replace the thermostat if necessary.
Was a problem found?
ÐVerify repairGo to Step 4
41. Ignition ªONº, engine ªOFFº.
2. Review and record Tech 2 Failure Records.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªDTCº info for DTC P0128.
Does the Tech 2 indicate DTC P0128 failed this
ignition?
ÐGo to Step 5
Refer to
Diagnostic
Aids
51. Ignition ªONº, engine ªOFFº.
2. Oberve the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº below the specified value?
139
C
(282
F)
Verify repairGo to Step 6
61. Ignition ªOFFº.
2. Disconnect the PCM and check the ECT signal
circuit for a short to ground or a short to the sensor
ground circuit.
3. If the ECT signal circuit is shorted, repair it as
necessary.
Was a problem found?
ÐVerify repair
Refer to Diag-
nostic
Go to Step 7
7Replace the PCM.
IMPORTANT:
The replacement PCM must be programmed.
Refer to
ON-Vehicle Service in Power Control Module
and Sensors for procedures.
And also refer to latest Service Bulletin.
Check to see if the latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ