2004 ISUZU TF SERIES oil change

SUPPLEMENTAL RESTRAINT SYSTEM 9A-5

System Description
The SRS consists of the SRS control unit, the driver
air bag assembly, the SRS coil assembly, the
passenger air bag assembly and the “AIR BAG”
warning lamp in the instrument cluster. The SRS
control unit, SRS coil assembly (driver side only),
driver air bag assembly, passenger air bag assembly
and connector wire make up the deployment loops.
The function of the deployment loops is to supply
current through air bag assembly, which will cause
deployment of the air bags in the event of a frontal
crash of sufficient force, up to 30 degrees off the
centerline of the vehicle. The air bag assemblies are

only supplied enough current to deploy when the SRS
control unit detects vehicle velocity changes severe
enough to warrant deployment.
The SRS control unit contains a sensing device which
converts vehicle velocity change to an electrical signal.
The electrical signal generated is processed by the
SRS control unit and then compared to a value stored
in memory. When the generated signal exceeds the
stored value, the SRS control unit will cause current to
flow through the air bag assembly deploying the air
bags.



RTW49JLF000101

4A-10 PROPELLER SHAFT
Diagnosis of Propeller Shaft and
Universal Joint

Condition Possible cause Correction
Rough surface on splined yoke;
burred nicked or worn. Replace the seal. Minor burrs can
be Smoothed by careful use of
crocus cloth or fine stone honing.
Replace the yoke if badly burred. Leak at the Front Slip Yoke (An
Occasional Drop of Lubricant
Leaking from the Splined Yoke is
Normal)
Defective transmission rear oil seal. Replace the transmission rear oil
seal and replenish the transmission
oil.
Worn universal joint bearings. Replace.
Improper lubrication. Lubricate as directed.
Universal Joint Noise.
Loose flange bolts. Tighten to specifications.
Loose bushing bolts on the rear
springs or upper and lower control
arms. Tighten the bolts to specified
torque. Ping, Snap, or Click in Drive Line
(Usually Heard on Initial Load after
the Transmission is in Forward or
Reverse Gear)
Loose or out-of-phase end yoke. Remove end yoke, turn 180
degrees from its original position,
lubricate the splines and reinstall.
Tighten the bolts and pinion nut to
specified torque.
Squeak Lack of lubricant. Lubricate joints and splines. Also
check for worn or brinelled parts.
Loose or missing bolts at the
flanges. Replace or tighten bolts to specified
torque.
Incorrectly set front joint angle. Install shim under the transmission
support mount to change the front
joint angle.
Shudder on Acceleration (Low
Speed)
Worn universal joint. Replace.
Incorrect shaft runout. Replace.
Shaft out of balance. Adjust.
Transmission rear housing bushing,
transfer case housing bushing worn.Replace.
Vibration
Yoke spline jammed. Replace.

ENGINE COOLING 6B – 7
DIAGNOSIS
Engine Cooling Trouble
Symptom Possible Cause Action
Low Engine Coolant level Replenish
Thermo meter unit faulty Replace
Faulty thermostat Replace
Faulty Engine Coolant temperature
sensor Repair or replace
Clogged radiator Clean or replace
Faulty radiator cap Replace
Low engine oil level or use of
improper engine oil Replenish or change oil
Clogged exhaust system Clean exhaust system or replace
faulty parts
Faulty Throttle Position sensor Replace throttle valve assembly
Open or shorted Throttle Position
sensor circuit Repair or replace
Engine overheating
Damaged cylinder head gasket Replace
Engine overcooling Faulty thermostat Replace
Faulty thermostat Replace Engine slow to warm–up
Thermo unit faulty Replace

6B – 8 ENGINE COOLING
Draining and Refilling Cooling System
Before draining the cooling system, inspect the system and
perform any necessary service to ensure that it is clean, does
not leak and is in proper working order. The engine coolan
t
(EC) level should be between the “MIN" and “MAX" lines o
f
reserve tank when the engine is cold. If low, check for leakage
and add EC up to the “MAX" line.
There should not be any excessive deposit of rust or scales
around the radiator cap or radiator filler hole, and the EC
should also be free from oil.
Replace the EC if excessively dirty.


P1010064
1. Completely drain the cooling system by opening the drain
plug at the bottom of the radiator.

2. Remove the radiator cap.
WARNING: To avoid the danger of being burned, do not
remove the cap while the engine and radiator are still hot.
Scalding fluid and steam can be blown out unde
r
pressure.
3. Disconnect all hoses from the EC reserve tank.
Scrub and clean the inside of the reserve tank with soap and water. Flush it well with clean water, then drain it.
Install the reserve tank and hoses.
4. Refill the cooling system with the EC using a solution that is at least 50 percent antifreeze.

Procedure for filling with coolant (in case of full change)
 Make sure that the engine is cool.
 Open radiator cap pour coolant up to filler neck.
 Pour coolant into reservoir tank up to “MAX" line.
 Tighten radiator cap and start the engine. After idling for 2
to 3 minutes, stop the engine and reopen radiator cap. If the
water level is lower, replenish.
WARNING: When the coolant is heated to a high
temperature, be sure not to loosen or remove the radiato
r
cap. Otherwise you might get scalded by not vapor or
boiling water. To open the radiator cap, put a piece of
thick cloth on the cap and loosen the cap slowly to reduce
the pressure when the coolant has become cooler.

6E–66 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Throttle Position Sensor (TPS)
The TPS is a potentiometer connected to throttle shaft
on the throttle body. It is installed to the main TPS and
idle switch.
The engine control module (ECM) monitors the voltage
on the signal line and calculates throttle position. As the
throttle valve angle is changed when accelerator pedal
moved. The TPS signal also changed at a moved
throttle valve. As the throttle valve opens, the output
increases so that the output voltage should be high.
The engine control module (ECM) calculates fuel
delivery based on throttle valve angle.
Crankshaft Position (CKP) Sensor
The CKP sensor is located on top of the flywheel
housing of the flywheel and fix ed with a bolt.
The CKP sensor is of the magnet coil type. The
inductive pickup sensors four gaps in the flywheel
ex citer ring and is used to determine the engine speed
and engine cylinder top dead center (TDC). (1) Throttle Position Sensor (TPS)
(2) Idle Switch

1 2
Characteristic of TPS -Reference-
0 0.51 1.52 2.53 3.54 4.5
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Pedal Position (%) (Tech2 Readin
g
Output Voltage (V)
(1) Crankshaft Position (CKP) Sensor
(2) Fly wheel with sensor slot

1 2

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–75
When control current flows to the timing control valve
(TCV) coil, the valve needle opens and the fuel annular
chamber flows through the orifice to the feed pump inlet.
Consequently, the pressure of the annular chamber
decreases and the hydraulic stopper is moved to the
retard side.
The timing control valve (TCV) acts as a variable
throttle, using the rapid opening and closing (cycling) of
the valve needle in the timing control valve (TCV).
At normal operation, the TCV controls the pressure
acting on the annular chamber so that the hydraulic
stopper cam move to any position, from the retard
position to the advance position. At this time, the duty
ratio is set by the pump control unit (PSG).
Duty ratio is the ratio of the time that the timing control
valve (TCV) is opened to one complete timing control
valve (TCV) operating cycle. A duty ratio change of
100% to 0% is an advance in injection timing. (The
VP44 displays an ON duty ratio.)The engine control module (ECM) contains
characteristic maps of the start of injection,
corresponding to engine operating conditions (engine
load, engine speed and engine coolant temperature).
The pump control unit (PSG) is constantly comparing
the set start of injection timing and the actual start of
injection timing. If there is a difference, the timing
control valve (TCV) is controlled by the duty ratio. (The
actual start of injection timing is determined from the
pump camshaft speed sensor.) (1) Coil
(2) From Annular Chamber
(3) To Feed Pump
(4) Orifice
(5) Valve Needle
Engine Load
Engine Speed
Engine Coolant
TemperatureEngine
Control
Module
(ECM)Pump
Control
Unit
(PSG)
Pump Camshaft
Speed Sensor
Timing
Control
Valve
(TCV)

6E–82 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL SERVICE INFORMATION
Serviceability Issues
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Accordingly, if commercially sold
sensor or switch is installed, it makes a wrong diagnosis
and turns on the check engine lamp.
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the check
engine lamp.
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the check
engine lamp to turn on if the vehicle is not maintained
properly. Restricted oil filters, fuel filters, and crankcase
deposits due to lack of oil changes or improper oil
viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor vehicle
maintenance can not be classified as a “non-vehicle
fault”, but with the sensitivity of OBD diagnostics,
vehicle maintenance schedules must be more closely
followed.
Related System Faults
Many of the OBD system diagnostics will not run if the
ECM detects a fault on a related system or component.
Visual/Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any
diagnostic procedure or diagnosing the cause of an
emission test failure. This can often lead to repairing a
problem without further steps. Use the following
guidelines when performing a visual/physical
inspection:
Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.
Inspect hoses that are difficult to see behind other
components.
Inspect all wires in the engine compartment for
proper connections, burned or chafed spots, pinched
wires, contact with sharp edges or contact with hot
exhaust manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain
when performing diagnostic procedures could result in
an incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to
effectively use this section of the Service Manual.
ON-BOARD DIAGNOSTIC (OBD)
On-Board Diagnostic (Self Diagnosis
System) Tests
A diagnostic test is a series of steps, the result of which
is a pass or fail reported to the diagnostic ex ecutive.
When a diagnostic test reports a pass result, the
diagnostic ex ecutive records the following data:
The diagnostic test has been completed since the
last ignition cycle.
The diagnostic test has passed during the current
ignition cycle.
The fault identified by the diagnostic test is not
currently active.
When a diagnostic test reports a fail result, the
diagnostic ex ecutive records the following data:
The diagnostic test has been completed since the
last ignition cycle.
The fault identified by the diagnostic test is currently
active.
The fault has been active during this ignition cycle.
The operating conditions at the time of the failure.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Ex ecutive are listed as
follow s:
Commanding the check engine lamp on and off
DTC logging and clearing
Current status information on each diagnostic
Diagnostic Information
The diagnostic charts and functional checks are
designed to locate a faulty circuit or component through
a process of logical decisions. The charts are prepared
with the requirement that the vehicle functioned
correctly at the time of assembly and that there are not
multiple faults present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented
by the diagnostic procedures contained in this manual.
The language of communicating the source of the
malfunction is a system of diagnostic trouble codes.
When a malfunction is detected by the control module, a
diagnostic trouble code is set and the check engine
lamp is illuminated.
Check Engine Lamp
The check engine lamp looks the same as the check
engine lamp you are already familiar with, the “Check
Engine” lamp.
Basically, the check engine lamp is turned on when the

6E –218 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
 Poor connection at ECM-Inspect harness connectors
for backed out 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 DTC P0380 display on the Tech2 while moving
connectors and wiring harnesses. A change in the
display will indicate the location of the fault.
Diagnostic Trouble Code (DTC) P0380 (Symptom Code 4) (Flash Code 66) Glow Relay Circuit Voltage Low
Step Action Value(s) Yes No
1Was 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 As Stored By ECU ” in
“ F0: Diagnostic Trouble Codes ”.
Is the DTC P0380 (Symptom Code 4) stored as
“ Present Failure ”? —Go to Step 3 Refer to
Diagnostic Aids and Go to Step
3
3 1. Using the Tech 2, ignition “On ” and engine “Off ”.
2. Select “F1: Clear DTC Information ” in “F0:
Diagnostic Trouble Codes ” with the Tech 2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU ” in the “F0:
Diagnostic Trouble Codes ”.
Was the DTC P0380 (Symptom Code 4) 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 glow relay or ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
— Verify repair Go to Step 5
5 Using the DVM and check the glow relay. 1. Ignition “Off ”, engine “Off ”.
2. Remove the glow relay from the relay box .
3. Check the relay coil.
Was the DVM indicated specified value?
Approx imately 105
Go to Step 6 Replace glow
relay and verify repair
94
3
4
2
1
X-5
C-57
Grow Relay