2004 ISUZU TF SERIES reset

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-73
Intermittent Check Engine Lamp
In the case of an “intermittent" fault, the MIL (“Check
Engine" lamp) may illuminate and then (after three trips)
go “OFF". However, the corresponding diagnostic
trouble code will be stored in the memory. When
unexpected diagnostic trouble codes appear, check fo
r
an intermittent malfunction.
A diagnostic trouble code may reset. Consult the
“Diagnostic Aids" associated with the diagnostic trouble
code. A physical inspection of the applicable sub–
system most often will resolve the problem.
Data Link Connector (DLC)
The provision for communication with the control
module is the Data Link Connector (DLC). The DLC is
used to connect to a Tech 2. Some common uses o
f
the Tech 2 are listed below:

Identifying stored Diagnostic Trouble Codes (DTCs).

Clearing DTCs.

Performing out put control tests.

Reading serial data.








060RW046
Verifying Vehicle Repair
Verification of vehicle repair will be more
comprehensive for vehicles with OBD system
diagnostic. Following a repair, the technician should
perform the following steps:
1. Review and record the Fail Records and/or Freeze
Frame data for the DTC which has been diagnosed
(Freeze Frame data will only be stored for an A or B
type diagnostic and only if the MIL has been
requested).
2. Clear DTC(s).
3. Operate the vehicle within conditions noted in the
Fail Records and/or Freeze Frame data.
4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.
Following these steps are very important in verifyin
g
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.
Reading Flash Diagnostic Trouble Codes
The provision for communicating with the Engine
Control Module (ECM) is the Data Link Connecto
r
(DLC). The DLC is located behind the lower front
instrument panel. It is used in the assembly plant to
receive information in checking that the engine is
operating properly before it leaves the plant.
The diagnostic trouble code(s) (DTCs) stored in the
ECM's memory can be read either through a hand-held
diagnostic scanner plugged into the DLC or by counting
the number of flashes of the Check Engine Lamp (MIL)
when the diagnostic test terminal of the DLC is
grounded. The DLC terminal “6" (diagnostic request) is
pulled “Low" (grounded) by jumpering to DLC terminal
“4", which is a ground wire.
This will signal the ECM that you want to “flash" DTC(s),
if any are present. Once terminals “4" and “6" have
been connected, the ignition switch must be moved to
the “ON" position, with the engine not running. At this
point, the “Check Engine" MIL should flash DTC12
three times consecutively.
This would be the following flash, sequence: "flash,
pause, flash?flash, long pause, flash, pause,
flash?flash, long pause, flash, pause, flash?flash". DTC
12 indicates that the ECM's diagnostic system is
operating. If DTC 12 is not indicated, a problem is
present within the diagnostic system itself, and should
be addressed by consulting the appropriate diagnostic
chart in DRIVEABILITY AND EMISSIONS.
Following the output of DTC 12, the “Check Engine" MIL
will indicate a DTC three times if a DTC is present, or i
t
will simply continue to output DTC12. If more than one
DTC three has been stored in the ECM's memory, the
DTC(s) will be output from the lowest to the highest,
with each DTC being displayed three times.
Reading Diagnostic Trouble Codes Using a
TECH 2
The procedure for reading diagnostic trouble code(s) is
to used a diagnostic Tech 2. When reading DTC(s),
follow instructions supplied by Tech 2 manufacturer.
For the 1998 model year, Isuzu dealer service
departments will continue to use Tech 2.

6E-74 3.5L ENGINE DRIVEABILITY AND EMISSIONS








0.4 Sec 0.4 Sec
.

ON

OFF




3.2 Sec.

1.2 Sec.



3.2 Sec.


0.4 Sec 0.4 Sec
.
ON

OFF


3.2 Sec.

1.2 Sec.


3.2 Sec.



Self-diagnosis Start

Normal Code (12)
Trouble Code (32)


121212141414323232

In case DTC 14 & 32 are stored

Clearing Diagnostic Trouble Codes
Important: Do not clear DTCs unless directed to do so
by the service information provided for each diagnostic
procedure. When DTCs are cleared, the Freeze Frame
and Failure Record data which may help diagnose an
intermittent fault will also be erased from memory.
If the fault that caused the DTC to be stored into
memory has been corrected, the Diagnostic Executive
will begin to count the “warm-up" cycles with no furthe
r
faults detected, the DTC will automatically be cleared
from the ECM memory.
To clear Diagnostic Trouble Codes (DTCs), use the
Tech 2 “clear DTCs" or “clear information" function.
When clearing DTCs follow instructions supplied by the
Tech 2 manufacturer.
When a Tech 2 is not available, DTCs can also be
cleared by disconnecting one of the following sources
for at least thirty (30) seconds.
To prevent system damage, the ignition key must be
“OFF" when disconnecting or reconnecting battery
power.

The power source to the control module. Examples:
fuse, pigtail at battery ECM connectors etc.

The negative battery cable. (Disconnecting the
negative battery cable will result in the loss of othe
r
on-board memory data, such as preset radio tuning).
On-Board Diagnosis (Self-Diagnosis)
1. The Engine Control Module (ECM) conducts a
self-test of most of the wiring and components in
the system each time the key is turned to ON, and
can detect faults in the system while the key is ON.
If a fault is detected, the ECM will store a trouble
code in memory and flash the CHECK ENGINE
indicator to alert the driver.
2. The Diagnostic Trouble Codes (DTC) can be
displayed by shorting together terminals and the
Data Link Connector (DLC) located belo
w
Instrument Panel of drivers side.
The CHECK ENGINE indicator will flash DTC 12
three times, followed by any DTC.If several DTC are
stored, each DTC will be displayed three times. The
DTC will be displayed in numerical order. The DTC
display will continue as long as the DLC is shorted.
Some DTC can cause other DTC to be stored, It is
important to diagnose and repair the lowes
t
numbered DTC first before going on to the highe
r
numbered DTC.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-77


F0: Diagnostic Trouble Code
F0: Read DTC Infor By Priority
F1: Clear DTC Information
F2: DTC Information
F0: History
F1: MIL SVS or Message Requested
F2: Last Test Failed
F3: Test Failed Since Code Cleared
F4: Not Run Since Code Cleared
F5: Failed This Ignition
F3: Freeze Frame/Failure Record
F1: Data Display
F0: Engine Data
F1: O2 Sensor Data
F2: Snapshot
F3: Miscellaneous Test
F0: Lamps
F0: Malfunction Indicator Lamps
F1: Relays
F0: Fuel Pump Relay
F1: A/C Clutch Relay
F2: EVAP
F0: Purge Solenoid
F3: IAC System
F0: RPM Control
F1: IAC Control
F4: Fuel System
F0: Fuel Trim Reset

F4: System Information
F0: MIL/System Status

F0: Diagnostic Trouble Code
The purpose of the "Diagnostic Trouble Codes" mode is
to display stored trouble code in the
ECM.
When "Clear DTC Information" is selected, a "Clea
r
DTC Information", warning screen appears.
This screen informs you that by cleaning DTC's "all
stored DTC information in the ECM will be erased".
After clearing codes, confirm system operation by test
driving the vehicle.
Use the "DTC Information" mode to search for a
specific type of stored DTC information.
History
This selection will display only DTCs that are stored in
the ECM's history memory. It will not display Type B
DTCs that have not requested the MIL ("Check Engine
Lamp"). It will display all type A and B DTCs tha
t
requested the MIL and have failed within the last 40
warm-up cycles. In addition, it will display all type C and
D DTCs that have failed within the last 40 warm-up
cycles.

MIL SVC or Message Request
This selection will display only DTCs that are requesting
the MIL. Type C and Type D DTCs cannot be displayed
using the MIL. Type C and D DTCs cannot be displayed
using this option.
This selection will report type B DTCs only after the MIL
has been requested.

Last Test Failed
This selection will display only DTCs that have failed the
last time the test run. The last test may have run during
a previous ignition cycle of a type A or type B DTC is
displayed. For type C and type D DTCs, the last failure
must have occurred during the current ignition cycle to
appear as last test fail.

Test Failed Since Code Cleared
The selection will display all active and history DTCs
that have reported a test failure since the last time
DTCs were cleared. DTCs that last failed more that 40
warm-up cycles before this option is selected will not be
displayed.

Not Run Since Code Cleared
This selection will display up to DTCs that have not run
since the DTCs were last cleared. Since any displayed
DTCs have not run, their condition (passing or failing) is
unknown.

Failed This Ignition
This selection will display all DTCs that have failed
during the present ignition cycle.

Freeze Frame/Failure Record
This selection will display stored various vehicle
information at the moment an emission related faul
t
when the MIL ("Check Engine Lamp") is commanded
on.
The Freeze Frame data will not be erased unless the
associated history DTC is cleared.

6E-80 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Tech 2
Parameter
Units Idle 2000rpm Definitions
23 A/C Request (Air
Conditioning) On/Off Off Off This displays the air conditioner request signal. This should display "On" when the air
conditioner switch is switched on.
24 A/C Clutch On/Off Off Off This displays whether the ECM has commanded the A/C compressor clutch "On" or
"Off".
25 EVAP Purge
Solenoid
(Evaporative
Emission) % 50
80 0 This displays the duty signal from the ECM to control the canister purge solenoid
valve.
26 Fuel Trim Cell 49
52 13
17 This displays dependent on engine speed and MAF sensor reading.
A plot of engine speed versus MAF amount is divided into the cells.
Fuel trim cell indicates which cell is currently active.
27 Fuel Pump On/Off On On This displays operating status for the fuel pump main relay.
This should display "On" when the key switch is turned on and while engine is
running.
28 Deceleration Fuel
Cutoff Active/ Inactive Inactive Inactive The ECM will command the deceleration fuel mode when it detects a closed throttle
position while the vehicle is traveling.
While in decreasing fuel mode, the ECM will decrease the amount of fuel delivered
by entering open loop and decreasing the injector pulse width.
29 Power Enrichment Yes/No No No The ECM will command power enrichment mode "Yes" when a large increase in
throttle position and load is detected.
While in power enrichment mode, the ECM will increase the amount of fuel delivered
by entering open loop and increasing the injector pulse width.
30 Vehicle Speed km/h or mph 0 0 This displays vehicle speed.
The vehicle speed is measured by ECM from the vehicle speed sensor.
31 Cam Signal Present/ Missing Present Present This displays input signal from the camshaft position sensor.
When the correct pulse is generated, signal is received.
32 PSP Switch
(Power Steering
Pressure) Normal Pressure /
High Pressure Normal PressureNormal PressureThis displays the power steering pressure signal.
This should display "High Pressure" when the steering is steered.
33 Security Code
Status Programmable/
Not
Programmable Programmable Programmable This should display "Programmable" when the correct security code & secret code
are programmed.
34 Security Code Okay/ Not Okay Okay Okay This should display "Okay" when the security code is correctly accepted.
35 Immobilizer
System Normal /
Abnormal Normal Normal This should display "Normal" when the immobilizer is correctly operated.
36 Malfunction
Indicator Lamp On/Off Off Off This displays operating status for the Check Engine Lamp.
This should display "On" when the Check Engine Lamp is turned on.
37 Time From Start   This displays the engine time elapsed since the engine was started.
If the engine is stopped, engine run time will be reset to 00:00:00

6E-84 3.5L ENGINE DRIVEABILITY AND EMISSIONS

F4: Fuel System
F0: Fuel Trim Reset
When the Tech 2 is operated, "Long Term Fuel Trim" is
reset to 0%.
Fuel Trim Reset
B1 Long Term Fuel Trim (Bank 1) 3 %
B2 Long Term Fuel Trim (Bank 2) 3 %
B1 Short Term Fuel Trim (Bank 1) 
1 %
B2 Short Term Fuel Trim (Bank 2) 
2 %
Fuel Trim Cell 53
Fuel Trim Learned (Bank 1) Yes
Fuel Trim Learned (Bank 2) Yes
B1 Long Term Fuel Trim 0%



Press "Reset" key.

Then, B1 & B2 Long Term Fuel Trim is reseted to
0%.


Press "Quit" Key.

6E-140 3.5L ENGINE DRIVEABILITY AND EMISSIONS Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P1508 B Idle Air Control System
Low/Closed 1. No DTC relating to MAF sensor, IAT sensor,
ECT sensor, TPS, CMP sensor, CKP sensor,
VSS and system voltage.
2. Engine speed is between 675rpm and
6000rpm.
3. Engine coolant temperature is more than
75
C.
4. Intake air temperature is between -10
C and
80
C.
5. Vehicle is stopping.
6. Small amount of intake air through the idle air
control valve. (Idle air control valve is sticking
at close position.) Above conditions are met
for 2 seconds. 1. IAC valve harness open circuit, short to
ground circuit or short to voltage circuit.
2. Poor connector connection.
3. IAC valve malfunction.
4. IAC valve is sticking at close position.
5. ECM malfunction. B13/
B14/
B16/
B17 -
22
P1509 B Idle Air Control System
High/Open 1. No DTC relating to MAF sensor, IAT sensor,
ECT sensor, TPS, CMP sensor, CKP sensor,
VSS and system voltage.
2. Engine speed is between 675rpm and
6000rpm.
3. Engine coolant temperature more than 75
C.
4. Intake air temperature is between -10
C and
80
C.
5. Vehicle is stopping.
6. Large amount of intake air through the idle air
control valve. (Idle air control valve is sticking
at open position.) Above conditions are met
for 2 seconds. Fuel cut is operated at high idle
speed.
Correct amount of air intake
through the idle air control
valve. (Correct movement of
the idle air control valve.)

1. IAC valve harness open circuit, short to
ground circuit or short to voltage circuit.
2. Poor connector connection.
3. IAC valve malfunction.
4. IAC valve is sticking at open position.
5. ECM malfunction. B13/
B14/
B16/
B17 - 65 P1601 D CAN BUS Off CAN BUS off condition is detected consecutively.
CAN BUS on condition is
detected consecutively for 2
seconds. 1. ECM and TCM communication circuit open,
short to ground or short to voltage.
2. Electrical interference.
3. ECM malfunction.
4. TCM malfunction. A10/
A11 - 67 U2104 D CAN BUS Reset Counter
Overrun 1. No DTC CAN BUS Off.
2. CAN valid counter does not change for 2
seconds. Torque reduction control is
disable.
CAN valid counter changes
consecutively for 2 seconds. 1. ECM and TCM communication circuit open,
short to ground or short to voltage.
2. Electrical interference.
3. ECM malfunction.
4. TCM malfunction. A10/
A11 P1767/
U2104 (AT)

6E-310 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) U2104 (FLASH CODE 67) CAN BUS
RESET COUNTER OVER-RUN



RTW46EMF000301
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)
67 U2104 D CAN BUS Reset
Counter Overrun 1. No DTC CAN BUS Off.
2. CAN valid counter does not change for 2 seconds. Torque reduction control is disable.

CIRCUIT DESCRIPTION
The engine control system in 6VE1 uses high speed
CAN bus system. The individual CAN bus systems are
connected via two interfaces and can exchange
information and data. This allows control modules tha
t
are connected to different CAN bus systems to
communicate. Engine control modules (ECM) in the
vehicle that require continuous, rapid communication
are connected to the high speed CAN bus. The engine
is continuously notified of the current engine load
status. Since the ECM has to react immediately to load
status changes, rapid communication is required
between the ECM and the automatic transmission
control module. The high speed CAN bus in the 6VE1 is
designed as a two-wire CAN bus (twisted pair). The
wires are shielded and twisted. The engine rate is 500
K
band.

DIAGNOSTIC AIDS
 Inspect the wiring for poor electrical connection at the
ECM. Look for possible bent, backed out, deformed
or damaged terminals. Check for weak terminal
tension as well. Also check for a chafed wire tha
t
could short to bare metal or other wiring. Inspect for a
broken wire inside the insulation.
 When diagnosing for a possible intermittent short o
r
open condition, move the wiring harness while
observing test equipment for a change.
 Inspect the wiring for EMI (Erectro-Magnetic
Interference). Check that all wires are properly routed
away from coil, and generator. Also check fo
r
improperly installed electrical options. When this test
is performed, turn “OFF" on electronic auto parts
switches to improperly for a noise preventing.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-311
Diagnostic Trouble Code (DTC) U2104 (Flash Code 67) CAN Bus Reset
Counter Over-Run

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 U2104 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 U2104 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 "Off".
2. Select "AW30-40LE" in the system selection menu
"Powertrain".
3. Select "Read DTC Info Ordered By Priority" in the
"Diagnositic Trouble Code".
Was the any DTC's P1767 or U2104 stored in this
ignition cycle?
- Refer to
"Automatic
Transmission
Workshop
Manual" & Go to
DTC Chart
P1767 or U2104 Go to Step 5
5
Check any accessory parts which may cause electric
interference.
Was the problem found?
- Remove the
accessory parts
and verify repair Go to Step 6
6
Check for poor/faulty connection at the TCM or ECM
connector. If a poor/faulty connection is found, repair
as necessary.
Was the problem found?
E-60(A)








- Verify repair Go to Step 7