Page 2257 of 3573

7A1±12
TRANSMISSION CONTROL SYSTEM (4L30±E)
ªCheck Transº Check
1. Indicator it is ON during 2 to 3 seconds at ignition (or
when the engine is cranked) but it is OFF after the
engine starts. The indicator is working normally
GOTO DIAGNOSTIC CHECK.
821RW261
Normal
C07RW047
2. Indicator it is flashing and the flash is 0.2 seconds ON
and 0.2 seconds OFF always when ignition is on
(engine cranked or not). This means that there is a
malfunction. GOTO DIAGNOSTICAbnormal
C07RW048
3. Indicator it is staying ON always when Ignition is ON.
1. This means that connection between the lamp
and the PCM is shorted to ground.
2. Verify if instrument panel terminal 3 of connector
I±9 is shorted to ground.
3. Verify if the PCM connector J1 (RED) terminal
A14 is shorted to ground.
4. Verify that the instrument panel terminal 15 of
connector I±9 is connected to battery.
5. IF problem solved: GOTO CHECK TRANS
INDICATOR.
NO:Replace Powertrain Control Module (PCM).
4. Indicator it is staying OFF with the ignition ON (engine
OFF).
1. This means that connection between the lamp
and the PCM is shorted to battery or opened.
2. Verify if instrument panel terminal 3 of connector
I±9 is shorted to battery or open.
3. Verify if the PCM connector J1 (RED) terminal
A14 is shorted to battery or open.
4. Verify that the instrument panel terminal 15 of
connector I±9 is connected to battery. If not,
check the fuses and the connections voltage.
5. IF problem solved: GOTO CHECK TRANS
INDICATOR.
NO: Replace Powertrain Control Module (PCM).
Page 2258 of 3573
TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±13
D07RW028
Tech2 OBD II Connection
In order to access OBD II Powertrain Control Module
(PCM) data, use of the Tech2 scan tool is required.
1. The electronic diagnosis equipment is composed of:
1. Tech2 (3000094) hand±held scan tool, and DLC
cable (3000095).
901RW176
2. SAE 16/19 adapter (3000098) (1), RS 232 loop
back connector (3000112) (2), and PCMCIA card
(3000117) (3).
F07RW033
Page 2259 of 3573
7A1±14
TRANSMISSION CONTROL SYSTEM (4L30±E)
2. Connecting the TECH2
901RW180
Legend
(1) PCMCIA Card
(2) RS 232 Loop Back Connector(3) SAE 16/19 Adapter
(4) DLC Cable
(5) Tech2
Before operating the Isuzu PCMCIA card with the
Tech 2, the following steps must be performed:
1. The Isuzu 98 System PCMCIA card (1) inserts
into the Tech 2 (5).2. Connect the SAE 16/19 adapter (3) to the DLC
cable (4).
3. Connect the DLC cable to the Tech 2 (5)
4. Make sure the vehicle ignition is off.
Page 2260 of 3573
TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±15
5. Connect the Tech 2 SAE 16/19 adaptor to the
vehicle DLC.
821RW262
821RW263
6. The vehicle ignition turns on.
7. Verify the Tech 2 power up display.
060RW009
NOTE: The RS232 Loop back connector is only to use for
diagnosis of Tech 2 and refer to user guide of the Tech 2.
8. The power up screen is displayed when you
power up the tester with the Isuzu systems
PCMCIA card. Follow the operating procedure
below.
Page 2261 of 3573
7A1±16
TRANSMISSION CONTROL SYSTEM (4L30±E)
060RW014060RW016±1
Page 2262 of 3573
TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±17
Menu
The following table shows, which functions are
used the available equipment versions.
F0: Diagnostic Trouble Codes
F0: Read DTC Info Ordered 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 Ran Since Code Cleared
F5: Failed This Ignition
F1: Data Display
3. DVOM
When instructed to use a voltmeter or ohmmeter
within a troubleshooting procedure, use only a high
impedance DVOM (Digital Volt Ohmmeter) such as
J±39200 or equivalent.
Page 2263 of 3573

7A1±18
TRANSMISSION CONTROL SYSTEM (4L30±E)
OBD II Diagnostic Management System
Powertrain Control Module (PCM) Location
C07RW005
Class 2 Serial Data Bus
OBD II technology requires a much more sophisticated
PCM than does OBD I technology. The OBD II PCM
diagnostic management system not only monitors
systems and components that can impact emissions, but
they also run active tests on these systems and
components. The decision making functions of OBD II
PCMs have also greatly increased. To accommodate this
expansion in diagnostic complexity, Isuzu engineers have
designed the Class 2 serial data bus, which meets SAE
J1850 recommended practice for serial data.
ªSerial Dataº refers to information which is transferred in a
linear fashion ± over a single line, one bit at a time. A ªData
Busº is an electronic pathway through which serial data
travels.TROOPER previously used a 5 volt data bus called
UART, which is an acronym for ªUniversal Asynchronous
Receive and Transmitº. When neither the vehicle's
control module nor the diagnostic tool, such as a Tech2,
are ªtalking,º the voltage level of the bus at rest is 5 volts.
The two computers talk to each other at a rate of 8,192
bits per second, by toggling or switching the voltage on
the data bus from 5 volts to ground.
Class 2 data, which is used on OBD II vehicles, is quite
different. Data is transferred at a rate of 10.4 kilobits per
second, and the voltage is toggled between zero and 7
volts.
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TRANSMISSION CONTROL SYSTEM (4L30±E)7A1±19
C07RT006
Class 2 data is also pulse width modulated. Each bit of
information can have one of two lengths: long or short. On
the other hand, UART data bits come in only one length
(short). The pulse width modulation of Class 2 data allows
better utilization of the data line.
The message carried on Class 2 data streams are also
prioritized. This means that if two devices try to
communication on the data line at the same time, only the
higher priority message will continue. The device with the
lower priority message must wait.
NOTE: The Class 2 data wire is always terminal 2 of the
new 16±terminal Data Link Connector (DLC).
16 ± Terminal Data Link Connector (DLC)
OBD II standardizes Data Link Connector (DLC)
configurations. The DLC, formerly referred to as the
ALDL, will be a 16±terminal connector found on the lower
left side of the driver's side instrument panel. All
manufacturers must conform to this 16±terminal
standard.
821RW262