1998 ISUZU TROOPER P0112

6E±2
ENGINE DRIVEABILITY AND EMISSIONS
Primary System-Based Diagnostic 6E±50. . . . . . . . .
Primary System-Based Diagnostic 6E±50. . . . . . .
Fuel Control Heated Oxygen Sensor 6E±50. . . . .
HO2S Heater 6E±50. . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Trim System Monitor Diagnostic
Operation 6E±50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Trim System Monitor Diagnostic
Operation 6E±50. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Trim Cell Diagnostic Weights 6E±50. . . . . . .
On-Board Diagnostic (OBD) System Check 6E±51.
A/C Clutch Control Circuit Diagnosis 6E±54. . . . . . .
Electronic Ignition System Diagnosis 6E±60. . . . . . .
Fuel Metering System Check 6E±60. . . . . . . . . . . . .
Idle Air Control (IAC) Valve 6E±60. . . . . . . . . . . . . . .
Fuel System Pressure Test 6E±60. . . . . . . . . . . . . . .
Fuel Injector Coil Test Procedure and Fuel
Injector Balance Test Procedure 6E±60. . . . . . . . . .
Knock Sensor Diagnosis 6E±65. . . . . . . . . . . . . . . . .
Powertrain Control Module (PCM) Diagnosis 6E±65
Multiple PCM Information Sensor DTCS Set 6E±65
Exhaust Gas Recirculation (EGR) Diagnosis
(For except EXPORT and
SOUTH AFRICA) 6E±68. . . . . . . . . . . . . . . . . . . . . . .
Engine Tech 2 Data Definitions and Ranges 6E±68
Typical Scan Data Values 6E±70. . . . . . . . . . . . . . . .
No Malfunction Indicator Lamp (MIL) 6E±74. . . . . . .
Malfunction Indicator Lamp (MIL) ªONº
Steady 6E±77. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Cranks But Will Not Run 6E±79. . . . . . . . . . .
Fuel System Electrical Test 6E±85. . . . . . . . . . . . . . .
Fuel System Diagnosis 6E±88. . . . . . . . . . . . . . . . . . .
Idle Air Control (IAC) System Check 6E±93. . . . . . .
Knock Sensor (KS) System Check
(Engine Knock, Poor Performance, or Poor
Economy) 6E±95. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Gas Recirculation (EGR) System
Check 6E±97. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Output
Check 6E±99. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PCM Diagnostic Trouble Codes 6E±101. . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0101
MAF System Performance 6E±104. . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0102
MAF Sensor Circuit Low Frequency 6E±107. . . . . .
Diagnostic Trouble Code (DTC) P0103
MAF Sensor Circuit High Frequency 6E±110. . . . . .
Diagnostic Trouble Code (DTC) P0107
MAP Sensor Circuit Low Voltage 6E±112. . . . . . . . . .
Diagnostic Trouble Code (DTC) P0108
MAP Sensor Circuit High Voltage 6E±115. . . . . . . . .
Diagnostic Trouble Code (DTC) P0112
IAT Sensor Circuit Low Voltage 6E±118. . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0113
IAT Sensor Circuit High Voltage 6E±121. . . . . . . . . . Diagnostic Trouble Code (DTC) P0117
ECT Sensor Circuit Low Voltage 6E±124. . . . . . . . . .
Diagnostic Trouble Code (DTC) P0118
ECT Sensor Circuit High Voltage 6E±127. . . . . . . . .
Diagnostic Trouble Code (DTC) P0121
TP System Performance 6E±130. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0122
TP Sensor Circuit Low Voltage 6E±133. . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0123
TP Sensor Circuit High Voltage 6E±136. . . . . . . . . .
Diagnostic Trouble Code (DTC) P0131
HO2S Circuit Low Voltage Bank 1
Sensor 1 6E±139. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0132
HO2S Circuit High Voltage Bank 1
Sensor 1 6E±142. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0134
HO2S Circuit Insufficient Activity Bank 1
Sensor 1 6E±145. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0151
HO2S Circuit Low Voltage Bank 2
Sensor 1 6E±148. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0152
HO2S Circuit HIGH Voltage Bank 2
Sensor 1 6E±151. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0171
Fuel Trim System Lean Bank 1 6E±154. . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0172
Fuel Trim System Rich Bank 1 6E±158. . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0174
Fuel Trim System Lean Bank 2 6E±162. . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0175
Fuel Trim System Rich Bank 2 6E±166. . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0201
Injector 1 Control Circuit 6E±170. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0202
Injector 2 Control Circuit 6E±173. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0203
Injector 3 Control Circuit 6E±176. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0204
Injector 4 Control Circuit 6E±179. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0205
Injector 5 Control Circuit 6E±182. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0206
Injector 6 Control Circuit 6E±185. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0325
KS Module Circuit 6E±188. . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0327
KS Sensor Circuit 6E±190. . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0336
58X Reference Signal Circuit 6E±193. . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0337
CKP Sensor Circuit Low Frequency 6E±195. . . . . . .
Diagnostic Trouble Code (DTC) P0341
CMP Sensor Circuit Performance 6E±198. . . . . . . . .
Diagnostic Trouble Code (DTC) P0342
CMP Sensor Circuit Low 6E±202. . . . . . . . . . . . . . . . .

6E±118
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0112 IAT Sensor Circuit Low Voltage
D06RW026
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

The engine has been running for over 2 minutes.

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

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

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

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

DTC P0112 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:

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.

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.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Verifies that the fault is present.

6E±119 ENGINE DRIVEABILITY AND EMISSIONS
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
ªshiftedº 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
FOHMS
Temperature vs. Resistance Values
(approximate)
100212177
80176332
60140667
4511 31188
35951802
25772796
15594450
5417280
±52312300
±15521450
±30±2252700
±40±40100700

6E±120
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0112±IAT Sensor Circuit Low 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 ªON,º engine ªOFF.º
2. Using a Tech 2, monitor the intake air temperature
(IAT).
Is the intake air temperature greater than the specified
value?
148
C
(283
F)
Go to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF.º Review and record
Tech 2 Failure Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor the ªSpecific DTCº info for
DTC P0112.
Does the Tech 2 indicate DTC P0112 failed this
ignition?
Ð
Refer to Test
Description
Refer to
Diagnostic
Aids
41. Ignition ªOFF.º
2. Disconnect the IAT sensor electrical connector.
3. Ignition ªON.º
4. Observe the intake air temperature on the Tech 2.
Is the intake air temperature below the specified value?
±38
C
(±36
F)
Go to Step 6Go to Step 5
51. Ignition ªOFF.º
2. Disconnect the PCM electrical connectors.
3. Check the IAT sensor signal circuit for a short to
ground.
Is the IAT sensor signal circuit shorted to ground?
ÐVerify repairGo to Step 7
6Replace the IAT sensor.
Is the action complete?
ÐVerify repairÐ
7Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±336
ENGINE DRIVEABILITY AND EMISSIONS
0016
Electrically Erasable Programmable Read
Only Memory (EEPROM)
The electrically erasable programmable read only
memory (EEPROM) is a permanent memory chip that is
physically soldered within the PCM. The EEPROM
contains the program and the calibration information that
the PCM needs to control powertrain operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable. If the PCM is replaced, the new PCM
will need to be programmed. Equipment containing the
correct program and calibration for the vehicle is required
to program the PCM.
Fuel Control Heated Oxygen Sensors
The fuel control heated oxygen sensors (Bank 1 HO2S 1
and Bank 2 HO2S 1) are mounted in the exhaust stream
where they can monitor the oxygen content of the exhaust
gas. The oxygen present in the exhaust gas reacts with
the sensor to produce a voltage output. This voltage
should constantly fluctuate from approximately 100 mV to
900 mV. The heated oxygen sensor voltage can be
monitored with Tech 2. By monitoring the voltage output
of the oxygen sensor, the PCM calculates the pulse width
command for the injectors to produce the proper
combustion chamber mixture.

Low HO2S voltage is a lean mixture which will result in
a rich command to compensate.

High HO2S voltage is a rich mixture which will result in
a lean command to compensate.
An open Bank 1 HO2S 1 signal circuit will set a DTC
P0134 and Tech 2 will display a constant voltage between
400-500 mV. A constant voltage below 300 mV in the
sensor circuit (circuit grounded) will set DTC P0131. A
constant voltage above 800 mV in the circuit will set DTC
P0132. Faults in the Bank 2 HO2S 1 signal circuit will
cause DTC 0154 (open circuit), DTC P0151 (grounded
circuit), or DTC P0152 (signal voltage high) to set.
0012
Intake Air Temperature (IAT) Sensor
The intake air temperature (IAT) sensor is a thermistor
which changes its resistance based on the temperature of
air entering the engine. Low temperature produces a high
resistance of 100,000 ohms at ±40
C (±40
F). High
temperature causes low resistance of 70 ohms at 130
C
(266
F) . The PCM supplies a 5-volt signal to the sensor
through a resistor in the PCM and monitors the signal
voltage. The voltage will be high when the incoming air is
cold. The voltage will be low when the incoming air is hot.
By measuring the voltage, the PCM calculates the
incoming air temperature. The IAT sensor signal is used
to adjust spark timing according to the incoming air
density.
Tech 2 displays the temperature of the air entering the
engine. The temperature should read close to the
ambient air temperature when the engine is cold and rise
as underhood temperature increases. If the engine has
not been run for several hours (overnight), the IAT sensor
temperature and engine coolant temperature should read
close to each other. A fault in the IAT sensor circuit will set
DTC P0112 or DTC P0113.

6E±2
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Circuit Description 6E±56. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±56. . . . . . .
Conditions for Clearing the MIL/DTC 6E±56. . . . .
Diagnostic Aids 6E±56. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0108
(Flash DTC 34)
MAP Sensor Circuit High Voltage 6E±58. . . . . . . . .
Circuit Description 6E±58. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±58. . . . . . .
Conditions for Clearing the MIL/DTC 6E±58. . . . .
Diagnostic Aids 6E±58. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0112
(Flash DTC 23) IAT Sensor Circuit Low
Voltage 6E±60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E±60. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±60. . . . . . .
Conditions for Clearing the MIL/DTC 6E±60. . . . .
Diagnostic Aids 6E±60. . . . . . . . . . . . . . . . . . . . . . . .
Test Description 6E±61. . . . . . . . . . . . . . . . . . . . . . .
Intake Air Temperature Sensor 6E±61. . . . . . . . . .
Diagnostic Trouble Code (DTC) P0113
(Flash DTC 23) IAT Sensor Circuit High
Voltage 6E±62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E±62. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±62. . . . . . .
Conditions for Clearing the MIL/DTC 6E±62. . . . .
Diagnostic Aids 6E±62. . . . . . . . . . . . . . . . . . . . . . . .
Test Description 6E±63. . . . . . . . . . . . . . . . . . . . . . .
Manifold Air Temperature Sensor 6E±63. . . . . . . .
Diagnostic Trouble Code (DTC) P0117
(Flash DTC 14) ECT Sensor Low Voltage 6E±65.
Circuit Description 6E±65. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±65. . . . . . .
Conditions for Clearing the MIL/DTC 6E±65. . . . .
Diagnostic Aids 6E±65. . . . . . . . . . . . . . . . . . . . . . . .
Test Description 6E±65. . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature Sensor 6E±66. . . . .
Diagnostic Trouble Code (DTC) P0118
(Flash DTC 14) ECT Sensor High Voltage 6E±67.
Circuit Description 6E±67. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±67. . . . . . .
Conditions for Clearing the MIL/DTC 6E±67. . . . .
Diagnostic Aids 6E±67. . . . . . . . . . . . . . . . . . . . . . . .
Test Description 6E±68. . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature Sensor 6E±68. . . . .
Diagnostic Trouble Code (DTC) P0121
(Flash DTC 33) AP Sensor Rationality 6E±70. . . . .
Circuit Description 6E±70. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±70. . . . . . .
Conditions for Clearing the MIL/DTC 6E±70. . . . .
Diagnostic Aids 6E±70. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0122
(Flash DTC 21) AP Sensor Low Voltage 6E±72. . .
Circuit Description 6E±72. . . . . . . . . . . . . . . . . . . . . Action Taken When the DTC Sets 6E±72. . . . . . .
Conditions for Clearing the MIL/DTC 6E±72. . . . .
Diagnostic Aids 6E±72. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0123
(Flash DTC 21) AP Sensor High Voltage 6E±75. . .
Circuit Description 6E±75. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±75. . . . . . .
Conditions for Clearing the MIL/DTC 6E±75. . . . .
Diagnostic Aids 6E±75. . . . . . . . . . . . . . . . . . . . . . . .
Test Description 6E±75. . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0182
(Flash DTC 15) FT Sensor Low Voltage 6E±78. . .
Circuit Description 6E±78. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±78. . . . . . .
Conditions for Clearing the MIL/DTC 6E±78. . . . .
Diagnostic Aids 6E±78. . . . . . . . . . . . . . . . . . . . . . . .
Test Description 6E±78. . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0183
(Flash DTC 15) FT Sensor High Voltage 6E±80. . .
Circuit Description 6E±80. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±80. . . . . . .
Conditions for Clearing the MIL/DTC 6E±80. . . . .
Diagnostic Aids 6E±80. . . . . . . . . . . . . . . . . . . . . . . .
Test Description 6E±80. . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0192
(Flash DTC 63) Rail Pressure Sensor Low
Voltage 6E±82. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E±82. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±82. . . . . . .
Conditions for Clearing the MIL/DTC 6E±82. . . . .
Diagnostic Aids 6E±82. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0193
(Flash DTC 63) Rail Pressure Sensor
High Voltage 6E±84. . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E±84. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±84. . . . . . .
Conditions for Clearing the MIL/DTC 6E±84. . . . .
Diagnostic Aids 6E±84. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1193
(Flash DTC 64) RPCV Circuit Open/Short 6E±86. .
Circuit Description 6E±86. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±86. . . . . . .
Conditions for Clearing the MIL/DTC 6E±86. . . . .
Diagnostic Aids 6E±86. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1194
(Flash DTC 61) Rail Pressure System
Low Voltage 6E±88. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E±88. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E±88. . . . . . .
Conditions for Clearing the MIL/DTC 6E±88. . . . .
Diagnostic Aids 6E±88. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1195
(Flash DTC 61) Rail Pressure System
High Voltage 6E±90. . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E±90. . . . . . . . . . . . . . . . . . . . .

6E±38
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
On- Board Diagnostic (OBD) System Check

StepActionValue(s)Ye sNo
11. Ignition ªON,º engine ªOFF.º
2. Observe the malfunction indicator lamp (MIL or
ªCheck Engineº lamp).
Is the MIL (ªCheck Engineº lamp)ªON?º
ÐGo to Step 2
Go to No MIL
(ªCheck
Engineº lamp)
21. Ignition ªOFF.º
2. Install a Tech 2.
3. Ignition ªON.º
4. Attempt to display ECM engine data with the Tech 2.
Does the Tech 2 display ECM data?
ÐGo to Step 3Go to Step 8
31. Using the Tech 2 output tests function, select MIL
(ªCheck Engineº lamp) dash lamp control and
command the MIL (ªCheck Engineº lamp) ªOFF.º
2. Observe the MIL (ªCheck Engineº lamp).
Did the MIL (ªCheck Engineº lamp) turn ªOFF?º
ÐGo to Step 4
Go to MIL
(ªCheck
Engineº lamp)
On Steady
4Attempt to start the engine.
Did the engine start and continue to run?
ÐGo to Step 5
Go to Cranks
But Will Not
Run
5Select ªDisplay DTCsº with the Tech 2.
Are any DTCs stored?
ÐGo to Step 6Go to Step 7
6Are two or more of the following DTCs stored?
A Group; P0337, P0342, P1193, P1404, P1405,
P1488
B Group; P0337, P0342
C Group; P0112, P0117, P0182, P0197
D Group; P0107, P0405, P1194, P1485
Ð
Go to Chart,
ªMultiple
ECM
Information
Sensor DTCs
Setº
Go to
applicable
DTC table
7Compare ECM data values displayed on the Tech 2 to
the typical engine scan data values.
Are the displayed values normal or close to the typical
values?
ÐGo to Step 8
Refer to
indicated
Component
System
Checks
81. Ignition ªOFF,º disconnect the ECM.
2. Ignition ªON,º engine ªOFF.º
3. Check the Class 2 data circuit for an open, short to
ground, or short to voltage. Also, check the DLC
ignition feed circuit for an open or short to ground
and the DLC ground circuit for an open.
4. If a problem is found, repair as necessary.
Was a problem found?
ÐGo to Step 2Go to Step 9
9Check the Tech 2 on other vehicle.
Was Tech 2 abnormal?
ÐGo to Step 11Go to Step 10
10Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
ÐGo to Step 2Ð
11Repair the Tech 2 or prepare another Tech 2.
Is the action complete?
ÐGo to Step 2Ð

6E±39 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
Engine Control Module ECM
Diagnosis
To read and clear diagnostic trouble codes, use a Tech 2.
IMPORTANT:Use of a Tech 2 is recommended to clear
diagnostic trouble codes from the ECM memory.
Diagnostic trouble codes can also be cleared by turning
the ignition ªOFFº and disconnecting the battery power
from the ECM for 30 seconds. Turning off the ignition and
disconnecting the battery power from the ECM will cause
all diagnostic information in the ECM memory to be
cleared. Therefore, all the diagnostic tests will have to be
re-run.
Since the ECM can have a failure which may affect only
one circuit, following the diagnostic procedures in this
section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the ECM connections
or the ECM is the cause of a problem, and the ECM is
replaced, but this does not correct the problem, one of the
following may be the reason:

There is a problem with the ECM terminal
connections. The terminals may have to be removed
from the connector in order to check them properly.

The problem is intermittent. This means that the
problem is not present at the time the system is being
checked. In this case, refer to the
Symptoms portion
of the manual and make a careful physical inspection
of all components and wiring associated with the
affected system.

There is a shorted solenoid, relay coil, or harness.
Solenoids and relays are turned ªONº and ªOFFº by
the ECM using internal electronic switches called
drivers. A shorted solenoid, relay coil, or harness will
not damage the ECM but will cause the solenoid or
relay to be inoperative.
Multiple ECM Information Sensor
DTCS Set
Circuit Description
The Engine Control Module ECM monitors various
sensors to determine the engine operating conditions.
The ECM controls fuel delivery, spark advance,
transmission operation, and emission control device
operation based on the sensor inputs.
The ECM provides a sensor ground to all of the sensors.
The ECM applies 5 volts through a pull-up resistor, and
determines the status of the following sensors by
monitoring the voltage present between the 5-volt supply
and the resistor:

The fuel temperature (FT) sensor

The engine coolant temperature (ECT) sensor

The Intake air temperature (IAT) sensor
The ECM provides the following sensors with a 5-volt
reference and a sensor ground signal:

The Intake throttle position sensor

The manifold absolute pressure sensor

The rail pressure sensor

The accelerator position sensor

The oil temperature sensor
The camshaft position sensor

The crankshaft position sensor

The EGR pressure sensor
The ECM monitors the signals from these sensors in
order to determine their operating status.
Diagnostic Aids
IMPORTANT:Be sure to inspect ECM and engine
grounds for being secure and clean.
A short to voltage in one of the sensor input circuits may
cause one or more of the following DTCs to be set:

P0337

P0342

P1193

P1404

P1405

P1488
IMPORTANT:If a sensor input circuit has been shorted
to voltage, ensure that the sensor is not damaged. A
damaged sensor will continue to indicate a high or low
voltage after the affected circuit has been repaired. If the
sensor has been damaged, replace it.
An open in the sensor ground circuit between the ECM
and the splice will cause one or more of the following
DTCs to be set:

P0337

P0342

P0117
A short to ground in the 5-volt reference A or B circuit will
cause one or more of the following DTCs to be set:

P0112

P0117

P0182

P0197
An open in the 5-volt reference circuit A, between the
ECM and the splice will cause one or more of the following
DTCs to be set:

P0107

P0405

P1194

P0122
An open in the 5-volt reference circuit B, between the
ECM and the splice will cause one or more of the following
DTCs to be set:

P1485
Check for the following conditions:

Poor connection at ECM. Inspect the harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damage
terminals, and a poor terminal-to-wire connection.

Damaged harness. Inspect the wiring harness for
damage. If the harness is not damaged, observe an
affected sensor's displayed value on the Tech 2 with
the ignition ªONº and the engine ªOFFº while you
move the connectors and the wiring harnesses
related to the following sensors:

ECT Sensor