2004 ISUZU TF SERIES engine remove

6E–186 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0351 IGNITION 1 CONTROL CIRCUIT
DIAGNOSTIC TROUBLE CODE (DTC) P0352 IGNITION 2 CONTROL CIRCUIT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ignition control circuit provides a zero volt or a 5 volt
signal to the ignition control module. The normal circuit
voltage is zero volts. When the module receives the 5
volt signal from the ECM, it provides a ground path for
the B+ voltage supplied to the ignition primary coil.
When the ECM turns off the 5 volts to the module, the
module will remove the ground path of the ignition
primary coils; causing the magnetic field produces a
voltage in the secondary coils which fires the spark
plug.The circuit between the ECM and the ignition control
module is monitored for an open circuit, short to voltage,
and short to ground. When the ECM detects a problem
in the ignition control circuit, it will set DTC P0351 or
P0352.
Diagnostic Aids
Check for the following conditions:
Poor connection at the ECM - Inspect the harness
connectors for backed-out terminals, improper
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0351 A Ignition 1 Control Circuit #1 or #4cylinder ignition signals are not
detected consecutively.No fail-safe function.
P0352 A Ignition 2 Control Circuit #2 or #3 cylinder ignition signals are not
detected consecutively.

6E–196 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0502 Vehicle Speed Sensor Circuit Low Input
Step A ction Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go 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 P0502 stored as “Present Failure”?—Go to Step 3Refer 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 P0502 stored in this ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the VSS, meter,
immobilizer control unit (if equipped), ECM and other
connectors. If a poor/faulty connection is found, repair
the faulty terminal.
Was the problem found?
—Verify repair Go to Step 5
5 Remove the VSS from the housing case and visually
check.
Was the problem found? —Go to Step 19Go to Step 6
68
23
27
910 C-56(J2)
B-68
B-24
E-44

6E–210 ENGINE DRIVEABILITY AND EMISSIONS
8 Using the DVM and check the “Check Engine” lamp
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. Remove the meter connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
Breaker box is not available:
1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Remove the meter connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 9
9 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 10
10 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 A ction Value(s) Yes No
J2-25
Breaker BoxB-24





C-56(J2)
B-24 3217

6E–212 ENGINE DRIVEABILITY AND EMISSIONS
Perform “I njector Balance Test” - Refer to Fuel
System Diagnosis.
Check the EVAP canister for fuel saturation - If full of
fuel, check canister control and hoses. Refer to
Evaporative (EVAP) Emission Control System.
Check for a leak in the fuel pressure regulator
diaphragm by checking the vacuum line to toe
regulator for the presence of fuel.An intermittent TP sensor output will cause the
system to go rich due to a false indication of the
engine accelerating.
Silicon contamination of the HO2S can also cause a
high HO2S voltage to be indicated. This condition is
indicated by a powdery white deposit on the portion
of the HO2S ex posed to the ex haust stream. If
contamination is noticed, replace the affected HO2S.
Diagnostic Trouble Code (DTC) P1167
Fuel Supply Sy stem Rich During Deceleration Fuel Cutoff
Step A ction Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go 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 P1167 stored as “Present Failure”?—Go to Step 3Refer 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 P1167 stored in this ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Throttle Position” in the data display.
Does the Tech 2 indicate correct “Throttle Position” in
accordance with accelerator pedal operation? —Go to Step 6Go to Step 5
5 Check for the following conditions.
Objects blocking the throttle valve.
Incorrectly installed.
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 12
6 1. Using the Tech 2, ignition “On” and engine “On”.
2. Monitor the “Manifold Absolute Pressure” in the
data display.
Does the Tech 2 indicate correct “Manifold Absolute
Pressure” in accordance with engine speed or
acceleration? —Go to Step 8Go to Step 7
7 Remove the MAP sensor and check for the following
conditions.
Objects blocking the air cleaner.
Objects blocking the MAP sensor.
Objects blocking the throttle valve.
Vacuum leaking at intake duct.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 13

6E–216 ENGINE DRIVEABILITY AND EMISSIONS
7 Remove the MAP sensor and check for the following
conditions.
Objects blocking the air cleaner.
Objects blocking the MAP sensor.
Objects blocking the throttle valve.
Vacuum leaking at intake duct.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 13
8 1. Using the Tech 2, ignition “On” and engine “On”.
2. Select the “Miscellaneous Test” and perform the
“IAC Control” in the “IAC System”.
3. Operate the Tech 2 in accordance with procedure.
Was the engine speed changed, when the IAC valve
is operating step by step?—Go to Step 10Go to Step 9
9 Check for the following conditions.
Objects blocking the IAC valve.
Objects blocking the throttle valve.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 14
10 Check for injector for the affected bank.
Refer to “Injector Coil Test & Injector Balance Test
Procedure” 6E-98 page.
Was the injector operation correct?
—Go to Step 11Refer to Injector
Coil Test &
Injector
Balance Test
Procedure
11 Check for fuel pressure.
Refer to “Fuel System Diagnosis” 6E-108 page.
Was the fuel pressure correct? —Go to Step 15Refer to Fuel
System
Diagnosis
12 Replace the TPS.
Is the action complete?—Veri fy repai r—
13 Replace the MAP sensor.
Is the action complete?—Veri fy repai r—
14 Replace the IAC valve.
Is the action complete?—Veri fy repai r—
15 Replace the O
2 sensor.
Was the problem solved?—Verify repair Go to Step 16
16 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 17
17 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 A ction Value(s) Yes No

6E–230 ENGINE DRIVEABILITY AND EMISSIONS
6 Using the DVM and check the Tacho output 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 meter connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
Breaker box is not available:
1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Disconnect the meter connector.
4. Check the circuit for open or short to ground
circuit.
Was the problem found?
—Repair faulty
harness and
verify repair Go to Step 7
7 Using the DVM and check the Tacho output circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the meter connector.
3. Check the circuit for short to power supply circuit.
Was the DVM indicated specified value?
Less than 1V Go to Step 8Repair faulty
harness and
verify repair
8 Check any accessory parts which may cause electric
interference or magnetic interference.
Was the problem found?—Remove the
accessory parts
and verify repair Go to Step 9 Step A ction Value(s) Yes No
J2-25
Breaker BoxB-24





1125C-56(J2) B-24
V
B-24
11

6E–234 ENGINE DRIVEABILITY AND EMISSIONS
12 Visually/physically inspect the secondary ignition
wires. Check for the following conditions:
Verify that all ignition wire resistance are less than
the specified value.
Verify that ignition wires are correctly routed to
eliminate cross-fitting.
Verify that ignition wires are not arcing to ground.
Spraying the secondary ignition wires with a light
mist of water may help locate an intermittent
problem.
Was a problem found?#1 cyl. 4.4k

#2 cyl. 3.6k

#3 cyl. 3.1k

#4 cyl. 2.8k
Verify repair Go to Step 13
13 1. Disconnect the spark plug high tension cable from
No.1 spark plug.
2. Install a spark tester at the end of the
disconnected ignition coil.
3. Clip the spark tester to a good ground.
4. Observe the spark tester while the engine is
cranking.
Was a crisp blue spark observed? (Only one or two
sparks followed by no result is considered the same
as “No Spark”.)—Go to Step 21Go to Step 14
14 1. Disconnect the ignition coil harness connector.
2. Check for an open or short circuit between the
ignition coil and the ECM.
Was a problem found?—Verify repair Go to Step 15
15 1. Ignition “On”.
2. Using a Digital Voltmeter (DVM) check the ignition
wire coil at the ignition coil harness connector.
Was the voltage equal to the specified value?Battery
voltage Go to Step 16Verify repair
16 1. Ignition “Off”.
2. With DVM, check for an open in the ground wire at
the ignition coil harness connector.
Was the ground wire OK?—Go to Step 17Verify repair
17 Replace the ignition coil, verify the repair.
Attempt to start the engine.
Is there still a problem?—Go to Step 18Verify repair
18 Use an ohmmeter to check the ignition coil primary
winding resistance.
Was the primary winding resistance approximately
equal to the specified value? 0.8-18k
Go to Step 19Go to Step 20
19 Use an ohmmeter to check the ignition coil secondary
winding resistance.
Was the primary winding resistance hear around the
to the specified value? 2.5k
Go to Step 21Go to Step 20
20 Replace the ignition coil.—Veri fy repai r—
21 1. Remove the spark plugs from all cylinders.
2. Visually inspect the spark plug electrodes.
3. Replace any spark plugs with loose or missing
electrodes or cracked insulators.
Did your inspection reveal any spark plugs exhibiting
ex cessive fouling?—Correct the
fouling
condition Go to Step 22 Step Action Value(s) Yes No

ENGINE DRIVEABILITY AND EMISSIONS 6E–237
7 1. Using a Tech 2, display the engine coolant
temperature and note the value.
2. Check the resistance of the engine coolant
temperature sensor.
Is the actual resistance near the resistance value in
the chart for the temperature that was noted?
—Go to Step 8Replace the
ECT sensor.
Verify repair
8 1. Using a Tech 2, display the MAP sensor value in
comparison with atmosphere temperature.
2. Check for a faulty, plugged, or incorrectly installed
MAP sensor.
Was the problem found?—Verify repair Go to Step 9
9 Visually/physically inspect all spark plug high-tension
cables. Check for the following conditions:
Verify that the resistance of all spark plug high-
tension cables are less than the specified value.
Verify that the all spark plug high-tension cables are
correctly fitted to eliminate cross-fitting.
Verify that the all spark plug high-tension cables are
not arcing to ground.
Spraying the spark plug high-tension cables with a
light mist of water may help locate an intermittent
problem.
Was a problem found?#1 cyl. 4.4k

#2 cyl. 3.6k

#3 cyl. 3.1k

#4 cyl. 2.8k
Verify repair Go to Step 10
10 Check for proper ignition voltage output with a spark
tester.
Was the problem found?—Verify repair Go to Step 11
11 1. Remove the spark plugs and check for gas or oil
fouling cracks, wear, improper gap, burned
electrodes, heavy deposits, or improper heat
range.
2. If spark plugs are fouled, the cause of fouling must
be determined before replacing the spark plugs.
Was a problem found?—Verify repair Go to Step 12
12 Check for a loose ignition control module ground.
Was a problem found?—Verify repair Go to Step 13
13 1. Check the ignition coil secondary resistance.
2. Replace the coil if it is greater than the specified
resistance.
Did the coil require replacement? 2.5k
Verify repair Go to Step 14 Step Action Value(s) Yes No
Temperature (°C) Resistance (
) (Approximately)
-20 26740
09120
20 3500
40 1464
60 664
80 333
100 175
120 102