2004 ISUZU TF SERIES check engine light

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-59
Carbon fouling of the spark plug is indicated by dry,
black carbon (soot) deposits on the portion of the spark
plug in the cylinder. Excessive idling and slow speeds
under light engine loads can keep the spark plug
temperatures so low that these deposits are not burned
off. Very rich fuel mixtures or poor ignition system
output may also be the cause. Refer to DTC P0172.
Oil fouling of the spark plug is indicated by wet oily
deposits on the portion of the spark plug in the cylinder,
usually with little electrode wear. This may be caused by
oil during break-in of new or newly overhauled engines.
Deposit fouling of the spark plug occurs when the
normal red-brown, yellow or white deposits o
f
combustion by products become sufficient to cause
misfiring. In some cases, these deposits may melt and
form a shiny glaze on the insulator around the cente
r
electrode. If the fouling is found in only one or two
cylinders, valve stem clearances or intake valve seals
may be allowing excess lubricating oil to enter the
cylinder, particularly if the deposits are heavier on the
side of the spark plug facing the intake valve.



TS23995
Excessive gap means that the air space between the
center and the side electrodes at the bottom of the
spark plug is too wide for consistent firing. This may be
due to excessive wear of the electrode during use.
A
check of the gap size and comparison to the gap
specified for the vehicle in Maintenance and Lubrication
will tell if the gap is too wide. A spark plug gap that is
too small may cause an unstable idle condition.
Excessive gap wear can be an indication of continuous
operation at high speeds or with engine loads, causing
the spark to run too hot. Another possible cause is an
excessively lean fuel mixture.



TS23992
Low or high spark plug installation torque or improper
seating can result in the spark plug running too hot and
can cause excessive center electrode wear. The plug
and the cylinder head seats must be in good contact fo
r
proper heat transfer and spark plug cooling. Dirty or
damaged threads in the head or on the spark plug can
keep it from seating even though the proper torque is
applied. Once spark plugs are properly seated, tighten
them to the torque shown in the Specifications Table.
Low torque may result in poor contact of the seats due
to a loose spark plug. Over tightening may cause the
spark plug shell to be stretched and will result in poo
r
contact between the seats. In extreme cases, exhaus
t
blow-by and damage beyond simple gap wear may
occur.
Cracked or broken insulators may be the result o
f
improper installation, damage during spark plug heat
shock to the insulator material. Upper insulators can be
broken when a poorly fitting tool is used during
installation or removal, when the spark plug is hit from
the outside, or is dropped on a hard surface. Cracks in
the upper insulator may be inside the shell and no
t
visible. Also, the breakage may not cause problems
until oil or moisture penetrates the crack later.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-67
What you should do
Step 1: Acquire information
A thorough and comprehensive customer check sheet
is critical to intermittent problem diagnosis. You should
require this, since it will dictate the diagnostic starting
point. The vehicle service history file is another
source for accumulating information about the
complaint.

Step 2: Analyze the intermittent problem
Analyze the customer check sheet and service history
file to determine conditions relevant to the suspect
system(s).
Using service manual information, you must identify,
trace and locate all electrical circuits related to the
malfunctioning system(s). If there is more than one
system failure, you should identify, trace and locate
areas of commonality shared by the suspect circuits.

Step 3: Simulate the symptom and isolate the
problem
Simulate the symptom and isolate the system by
reproducing all possible conditions suggested in Step 1
while monitoring suspected circuits/components
/
systems to isolate the problem symptom. Begin with the
most logical circuit/component.
Isolate the circuit by dividing the suspect system into
simpler circuits. Next, confine the problem into a smalle
r
area of the system. Begin at the most logical point (or
point of easiest access) and thoroughly check the
isolated circuit for the fault, using basic circuit tests.

Hints
You can isolate a circuit by:

Unplugging connectors or removing a fuse to
separate one part of the circuit from another

If only component fails to operate, begin testing
the component

If a number of components do not operate, begin
test at areas of commonality (such as powe
r
sources, ground circuits, switches, main
connectors or major components)

Substitute a known good part from the parts
department or the vehicle system

Try the suspect part in a known good vehicle See
Symptom Simulation Tests on the next page fo
r
problem simulation procedures. Refer to service
manual sections 6E and 8A for information abou
t
intermittent diagnosis. Follow procedures for basic
circuit testing in service manual section 8A.
What resources you should use
Whenever appropriate, you should use the following
resources to assist in the diagnostic process:

Service manual

Bulletins

Digital multimeter (with a MIN/MAX feature)

Tech 2 and Tech 2 upload function

Circuit testing tools (including connecto
r
kits/harnesses and jumper wires)

Experience

Intermittent problem solving simulation methods

Customer complaint check sheet
Symptom Simulation Tests
1. Vibration
This method is useful when the customer complain
t
analysis indicates that the problem occurs when the
vehicle/system undergoes some form of vibration.
For connectors and wire harness, slightly shake
vertically and horizontally. Inspect the connector join
t
and body for damage. Also, tapping lightly along a
suspected circuit may be helpful.
For parts and sensors, apply slight vibration to the par
t
with a light tap of the finger while monitoring the system
for a malfunction.
2. Heat
This method is important when the complaint suggests
that the problem occurs in a heated environment. Apply
moderate heat to the component with a hair drier o
r
similar tool while monitoring the system for a
malfunction.
CAUTION: Care must be take to avoid overheating
the component.
3. Water and Moisture
This method may be used when the complaint suggests
that the malfunction occurs on a rainy day or unde
r
conditions of high humidity. In this case, apply water in
a light spray on the vehicle to duplicate the problem.
CAUTION: Care must be take to avoid directly
exposing electrical connections to water.
4. Electrical loads
This method involves turning systems ON (such as the
blower, lights or rear window defogger) to create a load
on the vehicle electrical system at the same time you
are monitoring the suspect circuit/component.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E -101

NO CHECK ENGINE LAMP (MIL)

RTW46EM F000401

CIRCUIT DESCRIPTION
The “Check Engine" lamp (MIL) should always be
illuminated and steady with the ignition “ON" and the
engine stopped. Ignition feed voltage is supplied to the
MIL bulb through the meter fuse. The Engine Control
Module (ECM) turns the MIL “ON" by grounding the MIL
driver circuit.

DIAGNOSTIC AIDS
An intermittent MIL may be cased by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation. Check for the following items:

Inspect the ECM harness and connections fo
r
improper mating, broken locks, improperly formed o
r
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 MIL 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.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-117
CIRCUIT DESCRIPTION
When the ignition switch is turned “ON," the Engine
Control Module (ECM) will turn “ON" the in-tank fuel
pump. The in-tank fuel pump will remain “ON" as long
as the engine is cranking or running and the ECM is
receiving 58X crankshaft position pulses. If there are no
58X crankshaft position pulses, the ECM will turn the
in-tank fuel pump “OFF" 2 seconds after the ignition
switch is turned “ON" or 2 seconds after the engine
stops running.
The in-tank fuel pump is an electric pump within an
integral reservoir. The in-tank fuel pump supplies fuel
through an in-line fuel filter to the fuel rail assembly. The
fuel pump is designed to provide fuel at a pressure
above the pressure needed by the fuel injectors. A fuel
pressure regulator, attached to the fuel rail, keeps the
fuel available to the fuel injectors at a regulated
pressure. Unused fuel is returned to the fuel tank by a
separate fuel return line.
TEST DESCRIPTION
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Connect the fuel pressure gauge to the fuel feed line
as shown in the fuel system illustration. Wrap a shop
towel around the fuel pressure connection in order to
absorb any fuel leakage that may occur when
installing the fuel pressure gauge. With the ignition
switch “ON" and the fuel pump running, the fuel
pressure indicated by the fuel pressure gauge
should be 333-376 kPa (3.4-3.8 kg/cm
2 / 48-55 psi).
This pressure is controlled by the amount o
f
pressure the spring inside the fuel pressure regulator
can provide.
3. A fuel system that cannot maintain a constant fuel
pressure has a leak in one or more of the following
areas:
 The fuel pump check valve.
 The fuel pump flex line.
 The valve or valve seat within the fuel pressure
regulator.
 The fuel injector(s).
4. Fuel pressure that drops off during acceleration,
cruise, or hard cornering may case a lean condition.
A lean condition can cause a loss of power, surging,
or misfire. A lean condition can be diagnosed using
a Tech 1 Tech 2. If an extremely lean condition
occurs, the oxygen sensor(s) will stop toggling. The
oxygen sensor output voltage(s) will drop below 500
mV. Also, the fuel injector pulse width will increase.

Important: Make sure the fuel system is not operating
in the “Fuel Cut-Off Mode."
When the engine is at idle, the manifold pressure is
low (high vacuum). This low pressure (high vacuum)
is applied to the fuel pressure regulator diaphragm.
The low pressure (high vacuum) will offset the
pressure being applied to the fuel pressure regulato
r
diaphragm by the spring inside the fuel pressure
regulator. When this happens, the result is lower fuel
pressure. The fuel pressure at idle will vary slightly
as the barometric pressure changes, but the fuel
pressure at idle should always be less than the fuel
pressure noted in step 2 with the engine “OFF."
16.Check the spark plug associated with a particula
r
fuel injector for fouling or saturation in order to
determine if that particular fuel injector is leaking. I
f
checking the spark plug associated with a particular
fuel injector for fouling or saturation does no
t
determine that a particular fuel injector is leaking,
use the following procedure:
 Remove the fuel rail, but leave the fuel lines and
injectors connected to the fuel rail. Refer to Fue
l
Rail Assembly in On-Vehicle Service.
 Lift the fuel rail just enough to leave the fuel
injector nozzles in the fuel injector ports.
CAUTION: In order to reduce the risk of fire and
personal injury that may result from fuel spraying
on the engine, verify that the fuel rail is positioned
over the fuel injector ports and verify that the fuel
injector retaining clips are intact.
 Pressurize the fuel system by connecting a 10
amp fused jumper between B+ and the fuel pump
relay connector.

Visually and physically inspect the fuel injector
nozzles for leaks.
17. A rich condition may result from the fuel pressure
being above 376 kPa (55 psi). A rich condition may
cause a DTC P0132 or a DTC P0172 to set.
Driveability conditions associated with rich conditions
can include hard starting (followed by black smoke)
and a strong sulfur smell in the exhaust.
20.This test determines if the high fuel pressure is due
to a restricted fuel return line or if the high fuel
pressure is due to a faulty fuel pressure regulator.
21.A lean condition may result from fuel pressure belo
w
333 kPa (48 psi). A lean condition may cause a DTC
P0131 or a DTC P0171 to set. Driveability conditions
associated with lean conditions can include hard
starting (when the engine is cold ), hesitation, poo
r
driveability, lack of power, surging , and misfiring.

6E-288 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0562 (FLASH CODE 66) SYSTEM
VOLTAGE LOW

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)
66 P0562 D System Voltage Low Battery voltage is below 6V for more than 20 seconds. No fail-safe function.


CIRCUIT DESCRIPTION
The engine control module (ECM) monitors the system
voltage on the ignition feed terminals to the ECM.
A
system voltage DTC will set whenever the voltage is
above a calibrated value.

DIAGNOSTIC AIDS
If the DTC sets when an accessory is operated, check
for a poor connection or defective accessory.


Diagnostic Trouble Code (DTC) P0562 (Flash Code 66)
System Voltage Low
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 P0562 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 P0562 stored in this ignition cycle?
- Go to Step 4 Refer to
Diagnostic Aids
and Go to Step 4
4
1. Using the Tech 2, ignition "On" and engine "On".
2. Monitor the "Ignition Voltage" in the data display.
3. Load the electrical system by turning on the
headlights, etc..
Does the Tech 2 indicate enough ignition voltage?
10 – 14.5V Go to Step 6 Go to Step 5
5
Using the DVM and check the battery voltage at the
battery terminal.
Does the tester indicate enough battery voltage?
10 – 14.5V Go to Step 6 Check the
charging system,
charge or replace
the battery

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-291
DIAGNOSTIC TROUBLE CODE (DTC) P0563 (FLASH CODE 66)
SYSTEM VOLTAGE HIGH

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)
66 P0563 A System Voltage High Battery voltage is above 16V for more than 20 seconds. No fail-safe function.

CIRCUIT DESCRIPTION
The engine control module (ECM) monitors the system
voltage on the ignition feed terminals to the ECM.
A
system voltage DTC will set whenever the voltage is
above a calibrated value.
DIAGNOSTIC AIDS
If the DTC sets when an accessory is operated, check
for a poor connection or defective accessory.


Diagnostic Trouble Code (DTC) P0563 (Flash Code 66)
System Voltage High

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 P0563 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 P0563 stored in this ignition cycle?
- Go to Step 4 Refer to
Diagnostic Aids
and Go to Step
4
4
1. Using the Tech 2, ignition "On" and engine "On".
2. Monitor the "Ignition Voltage" in the data display.
3. Load the electrical system by turning on the
headlights, etc..
Does the Tech 2 indicate correct ignition voltage?
Less than 16VGo to Step 5 Check the
charging
system and Go
to Step 5
5
Is the battery jamp start cable incorrectly connecting?
- Verify
procedure Go to Step 6
6
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 7

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-329
SYMPTOM DIAGNOSIS
PRELIMINARY CHECKS
Before using this section, perform the "On-Board
Diagnostic (OBD) System Check" and verify all of the
following items:

The engine control module (ECM) and check engine
lamp (MIL=malfunction indicator lamp) are operating
correctly.

There are no Diagnostic Trouble Code(s) stored.

Tech 2 data is within normal operating range. Refer
to Typical Scan Data Values.

Verify the customer complaint and locate the correct
symptom in the table of contents. Perform the
procedure included in the symptom chart.

VISUAL/PHYSICAL CHECK
Several of the symptom procedures call for a careful
visual/physical check. This can lead to correcting a
problem without further checks and can save valuable
time. This check should include the following items:

ECM grounds for cleanliness, tightness and proper
location.

Vacuum hoses for splits, kinks, and proper
connection. Check thoroughly for any type of leak or
restriction.

Air intake ducts for collapsed or damaged areas.

Air leaks at throttle body mounting area, manifold
absolute pressure (MAP) sensor and intake manifold
sealing surfaces.

Ignition wires for cracking, harness, and carbon
tracking.

Wiring for proper connections, pinches and cuts.

INTERMITTENT
Important: An intermittent problem may or may not turn
on the check engine lamp (MIL=malfunction indicato
r
lamp) or store a Diagnostic Trouble Code. Do NOT use
the Diagnostic Trouble Code (DTC) charts fo
r
intermittent problems.
The fault must be present to locate the problem.
Most intermittent problems are cased by faulty electrical
connections or wiring. Perform a careful visual/physical
check for the following conditions.

Poor mating of the connector halves or a terminal
not fully seated in the connector (backed out).

Improperly formed or damaged terminal.


All connector terminals in the problem circuit should
be carefully checked for proper contact tension.

Poor terminal-to-wire connection. This requires
removing the terminal form the connector body to
check.

Ignition coils shorted to ground and arcing at ignition
wires or plugs.

Check engine lamp (MIL=malfunction indicator lamp)
wire to ECM shorted to ground.

Poor ECM grounds. Refer to the ECM wiring
diagrams.

Road test the vehicle with a Digital Multimete
r
connected to a suspected circuit. An abnormal voltage
when the malfunction occurs is a good indication tha
t
there is a fault in the circuit being monitored.
Using Tech 2 to help detect intermittent conditions. The
Tech 2 have several features that can be used to
located an intermittent condition. Use the following
features to find intermittent faults:
To check for loss of diagnostic code memory,
disconnect the mass air flow (MAF) sensor and idle the
engine until the check engine lamp (MIL=malfunction
indicator lamp) comes on. Diagnostic Trouble Code
P0102 should be stored and kept in memory when the
ignition is turned OFF.
If not, the ECM is faulty. When this test is completed,
make sure that you clear the Diagnostic Trouble Code
P0102 from memory.

An intermittent check engine lamp (MIL=malfunction
indicator lamp) with no stored Diagnostic Trouble Code
may be caused by the following:

Ignition coil shorted to ground and arcing at ignition
wires or plugs.

Check engine lamp (MIL=malfunction indicator lamp)
wire to ECM short to ground.

Poor ECM grounds. Refer to the ECM wiring
diagrams.

Check for improper installation of electrical options such
as light, cellular phones, etc. Check all wires from ECM
to the ignition control module for poor connections.
Check for an open diode across the A/C compresso
r
clutch and check for other open diodes (refer to wiring
diagrams in Electrical Diagnosis).

6-2 ENGINE DIAGNOSIS (C24SE)
Engine Diagnosis
Hard Starting
1.Starting Motor Does Not Turn Over
Trouble Shooting Procedure
Turn on headlights and starter switch.
Condition Possible cause Correction
Headlights go out or dim
considerably Battery run down or under
charged Recharge or replace battery
Terminals poorly connected Clean battery posts and terminals
and connect properly
Starting motor coil circuit shorted Overhaul or replace
Starting motor defective Overhaul or replace
2.Ignition Trouble - Starting Motor Turns Over But Engine Does Not Start
Spark Test
Disconnect a high tension cable from any spark plug.
Connect the spark plug tester (use commercially
available tool), crank the engine, and check if a spark is
generated in the spark plug tester. Before cranking the
engine, make sure that the spark plug tester is properly
grounded. To avoid electrical shock, do not touch the
high tension cable while the engine is running.

Condition Possible cause Correction
Spark jumps across gap Spark plug defective Clean, adjust spark gap or replace
Spark plug wire in correct Connect properly or replace
Ignition timing incorrect Refer to Ignition System
Fuel not reaching fuel injector(s)
or engine Refer to item 3 (Trouble in fuel
system)
Valve timing incorrect Adjust
Engine lacks compression Refer to item 4 (Engine lacks
compression)
No sparking takes place Ignition coil disconnected or
broken Connect properly or replace
Electronic Ignition System with
module Replace
Poor connections in engine
harness Correct
Engine Control Module cable
disconnected or defective Correct or replace