ISUZU TF SERIES 2004 Workshop Manual

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-165
Step Action Value (s) Yes No
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?
MAF & IAT Sensor






Temperature (
C) Resistance ()
(Approximately)
-20 15230
0 5760
20 2480
40 1185
60 584
80 332
100 183
120 11 9

Standard
resistance
Go to Step 7
Go to Step 12
7
Using the DVM and check the IAT sensor signal
circuit.
1. Ignition "On", engine "Off".
2. Disconnect the IAT sensor connector.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
E-63
V




Approximately
5.0V
Go to Step 10
Less than 1V:
Go to Step 8
More than
specified value:
Go to Step 9
8
Repair the open circuit between the ECM and IAT
sensor.
Was the problem solved?
E-60(A)
E-63




- Verify repair Go to Step 14

6E-166 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
9
Repair the short to voltage circuit between the ECM
and IAT sensor.
Was the problem solved?
E-60(A)
E-63




- Verify repair Go to Step 14
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?
E-63
V




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-95 page.
3. Disconnect the IAT sensor connector.
4. Check the circuit for open circuit.
Was the problem found?
B39
Breaker Box
E-63

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-167
Step Action Value (s) Yes No

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?
E-61(B)
E-63






- Repair faulty
harness and
verify repair Go to Step 14
12
Substitute a known good MAF & IAT sensor assembly
and recheck.
Was the problem solved?
- Go to Step 13 Go to Step 14
13
Replace the MAF & 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
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 -

6E-168 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0117 (FLASH CODE 14) ENGINE
COOLANT TEMPERATURE (ECT) SENSOR LOW INPUT



RUW46EMF000201

Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
14 P0117 A Engine Coolant
Temperature Sensor
Low Input
ECT sensor output voltage is below 0.08V. The ECM uses default engine
coolant temperature value based on
start-up ECT and time from start.

Circuit Description
The engine coolant temperature (ECT) sensor is a
thermistor mounted on a coolant crossover pipe at the
rear of the engine. 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 senso
r
resistance becomes lower, and the ECT signal voltage
measured at the ECM drops.

DIAGNOSTIC AIDS
Check for the following conditions:
 Poor connection at ECM – Inspect harness
connectors for backed-out terminals, imprope
r
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
 Damaged harness –Inspect the wiring harness fo
r
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 P0117 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.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-169
Diagnostic Trouble Code (DTC) P0117 (Flash Code 14) Engine Coolant
Temperature (ECT) 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?
E-69
E-60(A)







- Verify repair Go to Step 5
5
Visually check the ECT sensor.
Was the problem found?
- Go to Step 8 Go to Step 6

6E-170 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
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?
ECT Sensor






Temperature (
C) Resistance ()
(Approximately)
-20 30300
0 9850
20 3650
40 1540
60 649
100 182
120 104

Standard
resistance
Go to Step 7
Go to Step 8

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-171
Step Action Value (s) Yes No
7

Using the DVM and check the ECT 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-95 page.
3. Disconnect the ECT sensor connector.
4. Check the circuit for short to sensor ground or
ground circuit.
Was the problem found?
A21A22


Breaker Box




Breaker box is not available:
1. Ignition "Off", engine "Off".
2. Disconnect the ECT sensor connector.
3. Check the circuit for short to sensor ground or
ground circuit.
Was the problem found?
E-60(A)










-

Repair faulty
harness and
verify repair

Go to Step 10
8
Substitute a known good ECT sensor assembly and
recheck.
Was the problem solved?
- Go to Step 9 Go to Step 10
9
Replace the ECT sensor.
Is the action complete?
- Verify repair -
10
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 11

6E-172 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Step Action Value (s) Yes No
11
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 -

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-173
DIAGNOSTIC TROUBLE CODE (DTC) P0118 (FLASH CODE 14) ENGINE
COOLANT TEMPERATURE (ECT) SENSOR HIGH INPUT



RUW46EMF000201

Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
14 P0118 A Engine Coolant
Temperature Sensor
High Input ECT sensor output voltage is more than 4.8V. The ECM uses default engine
coolant temperature value based on
start-up ECT and time from start.

CIRCUIT DESCRIPTION
The engine coolant temperature (ECT) sensor is a
thermistor mounted in on a coolant crossover pipe a
t
the rear of the engine. 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 less, and the ECT signal
voltage measured at the ECM drops.

DIAGNOSTIC AIDS
Check for the following conditions:
 Poor connection at ECM – Inspect harness
connectors for backed-out terminals, imprope
r
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
 Damaged harness – Inspect the wiring harness fo
r
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.

6E-174 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0118 (Flash Code 14) Engine Coolant
Temperature (ECT) Sensor High 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 P0118 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 P0118 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?
E-69
E-60(A)







- Verify repair Go to Step 5
5 Visually check the ECT sensor. Was the problem
found? - Go to Step 12 Go to Step 6