Isuzu Trooper (1998-2002 year). Manual - part 443

6E–142

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

MAP 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 P0108 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,
performing the DTC P1108 Diagnostic Chart may isolate
the cause of the fault.

DTC P0108 – MAP Sensor Circuit High Voltage

 

Step

Action

Value(s)

Yes

No

1

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

—

Go to 

Step 2

Go to 

OBD

System

Check

2

1. If the engine idle is rough, unstable or incorrect,

repair the idle problem before using this chart. Refer
to 

Symptoms section.

2. With the engine idling, note the MAP value on the

Tech 2.

Is the MAP reading above the specified value?

25–35 kPa

Go to 

Step 4

Go to 

Step 3

3

1. Ignition “ON”, engine “OFF”.
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 “DTC” info for DTC P0108.

Does the Tech 2 indicate DTC P0108 failed this
ignition?

—

Go to 

Step 4

Check the

Procedure

Refer to

Diagnostic

Aids

4

1. Ignition “OFF”.
2. Disconnect the MAP sensor electrical connector.
3. Ignition “ON”.
4. Note the MAP sensor voltage displayed on the Tech

2. (If no, start with diagnostic chart for other sensors
in the circuit and see if 5V returns.)

Is the MAP sensor voltage at the specified value?

11 kPa 0.0 V

Go to 

Step 5

Go to 

Step 6

5

Probe the sensor ground circuit with a test light to B+.

Is the test light “ON”?

—

Go to 

Step 7

Go to 

Step 9

6

1. Check the MAP signal circuit for a short to voltage or

a short to the 5 volt reference circuit.

2. If the MAP sensor signal circuit is shorted, repair

circuit as necessary.

Was the MAP sensor signal circuit shorted?

—

Verify repair

Go to 

Step 11

7

1. Check for a poor sensor ground terminal connection

at the MAP sensor electrical connector.

2. If a problem is found, replace the faulty terminal.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 8

8

Check for a plugged or leaking vacuum supply to the
MAP sensor.

Is the vacuum supply plugged or leaking?

—

Verify repair

Go to 

Step 12

9

1. Check for a poor sensor ground terminal connection

at the PCM.

2. If a problem is found, replace the faulty terminal.

Did the terminal require replacement?

—

Verify repair

Go to 

Step 10

6E–143

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0108 – MAP Sensor Circuit High Voltage

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

1. Check the continuity of the MAP sensor ground

circuit.

2. If the MAP sensor ground circuit measures over 5

ohms, repair open or poor connection.

Was a condition found and corrected?

—

Verify repair

Go to 

Step 11

11

Replace 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?

—

Verify Repair

—

12

Replace the MAP sensor.

Is the action complete?

—

Verify repair

—

6E–144

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) 

P0112 IAT Sensor Circuit Low Voltage

D06RY00168

Circuit Description

The intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine.  The powertrain control module (PCM) applies 5
volts through a pull-up resistor to the IAT sensor.  When
the intake air is cold, the sensor resistance is high and the
PCM will monitor a high signal voltage on the IAT signal
circuit.  If the intake air is warm, the sensor resistance is
lower, causing the PCM to monitor a lower voltage.  DTC
P0112 will set when the PCM detects an excessively low
signal voltage on the intake air temperature sensor signal
circuit.

Conditions for Setting the DTC

D

The engine has been running for over 15 seconds.

D

Vehicle speed is greater than 30 mph (48 km/h) .

D

IAT signal voltage indicates and intake air temperature
greater than 148

°

C (298

°

F) (about 5 volts) for a total

of 12.5 seconds over a 25-second period of time.

Action Taken When the DTC Sets

D

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

D

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

D

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

D

A history DTC P0112 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

D

DTC P0112 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

Check for the following conditions:

D

Poor connection at PCM – Inspect harness connectors
for backed-bout terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

D

Damaged harness – Inspect the wiring harness for
damage.  If the harness appears to be OK, observe the
IAT display on the Tech 2 while moving connectors and
wiring harnesses related to the IAT sensor. A change
in the IAT display will indicate the location of the fault.

If DTC P0112 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

6E–145

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

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 P0112 can be repeated only by duplicating

the Failure Records condition, refer to the
Temperature vs. Resistance Value table.  The table
may be used to test the IAT sensor at various
temperatures to evaluate the possibility of a
“shifted” sensor that may be stored above or below
a certain temperature.  If this is the case, replace
the IAT sensor.  If the IAT sensor appears to be OK,
the fault is intermittent; refer to 

Diagnostic Aids.

Intake Air Temperature Sensor

°

C

°

F

OHMS

Temperature vs. Resistance Values

(approximate)

100

212

177

80

176

332

60

140

667

45

113

1188

35

95

1802

25

77

2796

15

59

4450

5

41

7280

–5

23

12300

–15

5

21450

–30

–22

52700

–40

–40

100700