Isuzu KB P190. Manual — part 574
6E–126
ENGINE DRIVEABILITY AND EMISSIONS
10
Using the DVM and check the MAP 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 MAP 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 MAP sensor connector and ECM
connector.
3. Check the circuit for open circuit.
Was the problem found?
—
Repair faulty
harness and
verify repair
Go to Step 11
11
Substitute a known good MAP sensor and recheck.
Was the problem solved?
—
Go to Step 12
Go to Step 13
12
Replace the MAP sensor.
Is the action complete?
—
Verify repair
—
13
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 14
14
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
J1-16
Breaker Box
Ω
E-85
1
1
16
E85
E60(J1)
ENGINE DRIVEABILITY AND EMISSIONS
6E–127
DIAGNOSTIC TROUBLE CODE (DTC) P0112 INTAKE AIR TEMPERATURE
SENSOR LOW INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine. The engine control module (ECM) 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 ECM will monitor a high signal voltage on the IAT
signal circuit. If the intake air is warm, the sensor
resistance is lower, causing the ECM to monitor a lower
voltage. Diagnostic Trouble Code P0112 will set when
the ECM detects an excessively low signal voltage
(short to ground) on the intake air 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 and open
Code
Type
DTC Name
DTC Setting Condition
Fail-Safe (Back Up)
P0112
A
Intake Air Temperature Sensor Low
Input
1. No DTC relating to VSS.
2. Vehicle speed is more than 25km/h.
3. Engine run time is longer than 120 sec-
onds.
4. IAT sensor output is more than 149 deg. C.
The ECM uses 20 deg. C condition as
substitute.
6E–128
ENGINE DRIVEABILITY AND EMISSIONS
circuit. 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.
Diagnostic Trouble Code (DTC) P0112
Intake Air 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 P0112 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 P0112 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 IAT 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
Remove the IAT sensor and visually check.
Was the problem found?
—
Go to Step 8
Go to Step 6
C56(J2)
C121
1
22
ENGINE DRIVEABILITY AND EMISSIONS
6E–129
6
Using the DVM and check the IAT sensor.
1. Ignition “Off”, engine “Off”.
2. Disconnect IAT sensor connector.
3. Measure the resistance of IAT sensor.
Does the tester indicate standard resistance as shown
in the following table?
Standard
resistance
Go to Step 7
Go to Step 8
7
Using the DVM and check the IAT sensor signal
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 short to sensor ground or
ground 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 short to sensor ground or
ground circuit.
Was the problem found?
—
Repair faulty
harness and
verify repair
Go to Step 10
Step
Action
Value(s)
Yes
No
Temperature (°C)
Resistance (
Ω) (Approximately)
-20
32500
0
9910
20
3400
40
1509
60
670
80
329
100
182
120
101
2
1
IAT Sensor
Ω
1
2
J2-1
J2-22
Breaker Box
Ω
Ω
C56(J2)
1
22
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