4jh1 ISUZU TF SERIES 2004 Workshop Manual

6E–106 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
6. The Tech2 parameters which is not within the typical
range may help to isolate the area which is causing the
problem.12. This vehicle is equipped with ECM which utilizes an
electrically erasable programmable read only memory
(EEPROM).
On-Board Diagnostic (OBD) System Check
Step Action Value(s) Yes No
11. Ignition “On”, engine “Off”.
2. Check the “CHECK ENGINE” lamp (MIL).
Does the “CHECK ENGINE” lamp turn “On”?—Go to Step 2Go to No
CHECK
ENGINE Lamp
21. Using the Tech 2, ignition “On” and engine “Off”.
2. Attempt to display “Data Display” with the Tech 2.
Does the Tech 2 display engine data? —Go to Step 3Go to Step 7
31. Using the Tech 2, ignition “On” and engine “Off”.
2. Select the “Miscellaneous Test” and perform the
“Check Light” in “Lamps”.
3. Operate the Tech 2 in accordance with the Tech 2
instructions.
Does the “CHECK ENGINE” lamp turn “Off”? —Go to Step 4Go to CHECK
ENGINE LAMP
On Steady
4Attempt to start the engine.
Does the engine start and continue to “Run”?
—Go to Step 5Go to Engine
Cranks But Will
Not Run
51. Using the Tech 2, ignition “On” and engine “Off”.
2. Select the “Read DTC Infor As Stored By ECU” in
“Diagnostic Trouble Code”.
3. Are any DTCs stored?—Go to DTC
ChartGo to Step 6
6Compare typical scan data values displayed on the
Te c h 2 “Data Display”.
Are the displayed values within the range?—Refer to
SYMPTOM
DIAGNOSISRefer to
TYPICAL
SCAN DATA
7Using the DVM and check the data link connector
power supply circuit.
1. Ignition “Off”, engine “Off”.
2. Check the circuit for open circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 8
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–107
8Using the DVM and check the data link connector
ground circuit.
1. Ignition “Off”, engine “Off”.
2. Check the circuit for open circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 9
9Using the DVM and check the data link connector
ground circuit.
1. Ignition “On”, engine “Off”.
2. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Less than 1V Go to Step 10Repair faulty
harness and
verify repair
10Using the DVM and check the data link connector
communication circuit.
1. Ignition “On”, engine “Off”.
2. Check the circuit for short to power supply circuit.
Was the DVM indicated fix ed battery voltage?
—Repair faulty
harness and
verify repair Go to Step 11 Step Action Value(s) Yes No
5 4
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5 4
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6E–108 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
11Using the DVM and check the data link connector
communication circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Check the circuit for open or short to ground
circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 12
12Is 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 13
13Replace 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.—Veri fy repai r— Step Action Value(s) Yes No





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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–109
NO CHECK ENGINE LAMP (MIL)
Circuit Description
The check engine lamp should be illuminated and
steady for about five seconds with the ignition “ON” and
the engine stopped. Ignition feed voltage is supplied to
the check engine lamp bulb through the meter fuse.
The Engine Control Module (ECM) turns the check
engine lamp “ON” by grounding the check engine lamp
driver circuit.
Diagnostic Aids
An intermittent check engine lamp may be cased by a
poor connection, rubbed-through wire insulation, or awire broken inside the insulation. Check for the
following items:
Inspect the ECM harness and connections for
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
If the engine runs OK, check for a faulty light bulb, an
open in the check engine lamp driver circuit, or an
open in the instrument cluster ignition feed.
If the engine cranks but will not run, check for an
open ECM ignition or battery feed, or a poor ECM to
engine ground.

6E–110 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
No Check Engine Lamp (MIL)
Step Action Value(s) Yes No
1 Check the meter fuse (15A).
If the fuse is burnt out, repair as necessary.
Was the problem found?—Verify repair Go to Step 2
2 Using the DVM and check the “CHECK ENGINE”
lamp circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Ignition “On”.
4. Check the circuit for open circuit.
Was the DVM indicated specified value?
10-14.5V Go to Step 5Go to Step 3
3 Check the “CHECK ENGINE” lamp bulb.
If the bulb is burnt out, repair as necessary.
Was the problem found?—Verify repair Go to Step 4
4 Using the DVM and check the “CHECK ENGINE”
lamp circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the meter connector and ECM
connector.
3. Check the circuit for open circuit.
Was the problem found?
—Verify repair Go to Step 5
5 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 6
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4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–111
6 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.—Veri fy repai r— Step Action Value(s) Yes No

6E–112 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
CHECK ENGINE LAMP (MIL) “ON” STEADY
Circuit description
The check engine lamp should always be illuminated
and steady for about five seconds with ignition “ON” and
the engine stopped. Ignition feed voltage is supplied
directly to the check engine lamp indicator. The Engine
Control Module (ECM) turns the check engine lamp
“ON” by grounding the check engine lamp driver circuit.
The check engine lamp should not remain “ON” with the
engine running and no DTC(s) set. A steady check
engine lamp with the engine running and no DTC(s)
suggests a short to ground in the check engine lamp
driver circuit.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation. Check for the following items:
Poor connection or damaged harness – Inspect the
ECM harness and connectors for improper mating,
broken locks, improperly formed or damaged
terminals, poor terminal-to-wire connection, and
damaged harness.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–11 3
Check Engine Lamp (MIL) On Steady
Step Action Value(s) Yes No
1 1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Ignition “On”.
Was the “CHECK ENGINE” lamp turned on?—Go to Step 2 Go to Step 4
2 Using the DVM and check the “CHECK ENGINE”
lamp circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the meter connector and ECM
connector.
3. Check the circuit for short to ground circuit.
Was the problem found?
—Veri fy repai rGo to Step 3
3 Replace the meter assembly.
Is the action complete?—Veri fy repai r—
4 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?—Veri fy repai rGo to Step 5
5 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.—Veri fy repai r—
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6E–114 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONSECM Diagnostic Trouble CodesFlash
CodeCodeSymptom
CodeMILDTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure PartsRelated
ECM Pin
No.Related
Multiple
DTC4JA1-TC
(MT)4JH1-TC
(MT)4JH1-TC
(AT)
65 P0100 7 ON Mass Air Flow (MAF) Sensor
Voltage Supply Circuit High
InputMAF sensor power supply
voltage is more than 5.2V.ECM uses mass air flow
1600mg/strk & EGR 10%
conditions as substitute.MAF sensor power supply
voltage is below 5.2V.1. Sensor power supply
circuit short to battery
voltage circuit.
2. MAF sensor malfunction.
3. ECM malfunction.83 —
9 ON Mass Air Flow (MAF) Sensor
Voltage Supply Circuit Low
InputMAF sensor power supply
voltage is below 4.6V.MAF sensor power supply
voltage is more than 4.6V.1. Sensor power supply
circuit short to ground
c i r c u i t .
2. MAF sensor malfunction.
3. ECM malfunction.83 —
B ON Mass Air Flow (MAF) Sensor
Output Circuit Low Input1. Engine speed is between
600rpm and 5000rpm.
2. MAF sensor output is
below -33.7mg/strk.MAF sensor output is more
than -27.4mg/strk.1. Sensor power supply
circuit open circuit.
2. Sensor signal circuit
open or short to ground
c i r c u i t .
3. Sensor heater harness
o p e n c i r c u i t .
4. Poor connector
c o n n e c t i o n .
5. MAF sensor malfunction.
6. ECM malfunction.8 3 /
88P0110(1)
C ON Mass Air Flow (MAF) Sensor
Output Circuit High Input1. Engine speed is between
600rpm and 5000rpm.
2. MAF sensor output is
more than 1378mg/strk
(4JA1-TC) or 1784mg/
strk (4JH1-TC).MAF sensor output is below
1378mg/strk (4JA1-TC) or
1784mg/strk (4JH1-TC).1. Sensor signal circuit
short to voltage circuit.
2. Sensor ground circuit
open or short to voltage
c i r c u i t .
3. MAF sensor malfunction.
4. ECM malfunction.8 8 /
92P0110(1)
34 P0105 1 ON Vacuum Pressure Sensor
Circuit High InputVacuum sensor output
voltage is more than 4.4V.1. Fuel injection quantity is
r e d u c e d .
2. ECM use 615hpa
conditions for
turbocharger waste gate
control.Vacuum sensor output
voltage is below 4.4V.1. Sensor signal circuit
short to voltage circuit.
2. Sensor ground circuit
open or short to voltage
c i r c u i t .
3. Vacuum sensor
m a l f u n c t i o n .
4. ECM malfunction.8 5 /
93P0115(1) —
2 ON Vacuum Pressure Sensor
Circuit Low InputVacuum sensor output
voltage is below 0.5V.Vacuum sensor output
voltage is more than 0.5V.1. Sensor power supply
circuit open circuit.
2. Sensor signal circuit
open or short to ground
c i r c u i t .
3. Poor connector
c o n n e c t i o n .
4. Vacuum sensor
m a l f u n c t i o n .
5. ECM malfunction.8 2 /
85——

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–115
34 P0105 7 ON Vacuum Pressure Sensor
Voltage Supply Circuit High
InputVacuum sensor power
supply voltage is more than
5.2V.1. Fuel injection quantity is
r e d u c e d .
2. ECM use vacuum sensor
output voltage 5.0V
condition as substitute.Vacuum sensor power
supply voltage is below 5.2V.1. Sensor power supply
circuit short to battery
voltage circuit.
2. Vacuum sensor
m a l f u n c t i o n .
3. ECM malfunction.82 — —
9 ON Vacuum Pressure Sensor
Voltage Supply Circuit Low
InputVacuum sensor power
supply voltage is below 4.5V.Vacuum sensor power
supply voltage is more than
4.5V.1. Sensor power supply
circuit short to ground
c i r c u i t .
2. Vacuum sensor
m a l f u n c t i o n .
3. ECM malfunction.82 — —
23 P0110 1 ON Intake Air Temperature (IAT)
Sensor Circuit High InputIAT sensor output voltage is
more than 4.7V.ECM use 0 deg. C conditions
as substitute.IAT sensor output voltage is
below 4.7V.1. Sensor signal circuit
open or short to voltage
c i r c u i t .
2. Sensor ground circuit
open or short to voltage
c i r c u i t .
3. Poor connector
c o n n e c t i o n
4. IAT sensor malfunction.
5. ECM malfunction.8 4 /
92P0100(B)/







P0100(C)
2 ON Intake Air Temperature (IAT)
Sensor Circuit Low InputIAT sensor output voltage is
below 0.3V.IAT sensor output voltage is
more than 0.3V.1. Sensor signal circuit
short to ground circuit.
2. IAT sensor malfunction.
3. ECM malfunction.84 —
14 P0115 1 ON Engine Coolant Temperature
(ECT) Sensor Circuit High
InputECT sensor output voltage is
more than 4.7V.1. ECM uses fuel
temperature as
s u b s t i t u t e .
2. ECM uses 60 deg. C
condition for injection
t i m i n g c o n t r o l .
3. ECM uses -25 deg. C
condition (4JA1-TC) or -
15 deg. C condition
(4JH1-TC) for glow time
control.ECT sensor output voltage is
below 4.7V.1. Sensor signal circuit
open or short to voltage
c i r c u i t .
2. Sensor ground circuit
open or short to voltage
c i r c u i t .
3. Poor connector
c o n n e c t i o n
4. ECT sensor malfunction.
5. ECM malfunction.8 9 /
93P0105(1)
2 ON Engine Coolant Temperature
(ECT) Sensor Circuit Low
InputECT sensor output voltage is
below 0.3V.ECT sensor output voltage is
more than 0.3V.1. Sensor signal circuit
short to ground circuit.
2. ECT sensor malfunction.
3. ECM malfunction.89 —
15 P0180 B ON Fuel Temperature Sensor
Circuit Range/PerformanceFT sensor output is high
temperature (more than 150
deg. C) or low temperature
(below -40 deg. C).The ECM use 75 deg. C
conditions as substitute.FT sensor output is correct
temperature range between
150 deg. C and -40 deg. C.1 . E C M m a l f u n c t i o n .
2. PSG (pump control unit)
malfunction.—— Flash
CodeCodeSymptom
CodeMILDTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure PartsRelated
ECM Pin
No.Related
Multiple
DTC4JA1-TC
(MT)4JH1-TC
(MT)4JH1-TC
(AT)