Isuzu KB P190. Manual - part 995

7A2-14  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

Item Description 

Diagnosis function 

•  If there is an abnormality in vehicle sensors, each solenoid (S1, S2, SL, STH), 

or throttle position sensor, "CHECK TRANS" lamp is actuated to warn the drive. 

But when the abnormality items have been restored to normal, the light does 

not blink. 

•  Faulty parts are memorized in TCM. If self-diagnosis start signal is inputted, 

"CHECK TRANS" lamp is blinked and results of diagnosis are indicated. A 

history of faults remains recorded even when IGN switch is off. If DG1 switch 

signal is inputted, or by using F1: Clear DTC Information for TECH 2, the 

records can be erased. 

TECH 2 

•  Output of control data in the TCM 
•  Actuator (Solenoid) operation check 
•  Erasure of trouble code 
•  Output of DTC code 

 
 

TRANSMISSION CONTROL SYSTEM (AW30–40LE)  7A2-15 

Functions of Input / Output Components 

 

 

 

 

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7A2-16  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

CAN bus systems in automatic 
transmission control (AW30-40LE) 

The automatic transmission control system in AW30-
40LE 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 that are connected to different CAN bus
systems to communicate. 

High speed CAN bus 

Transmission control module in the vehicle that require
continuous, rapid communication are connected to the
high speed CAN bus. For example, the automatic
transmission is continuously notified of the current 
engine load status. Since the automatic transmission
control module has to react immediately to load status
changes, rapid communication is required between the
engine control module and the automatic transmission
control module. The high speed CAN bus in the AW30-
40LE is designed as a two-wire CAN bus (twisted pair).
The wires are shielded and twisted. The transfer rate is
500 K baud. 

 

 
 
 
 

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Diagnosis 

Electronic Diagnosis 

How To Diagnose The Problem 

  1. To avoid incorrect diagnostics, this book needs to

be followed accurately. Unless stated, do not jump
directly to a section that could contain the
solution. Some important information may be
missed. 

  2. The sections in CAPITALS and bold are the main

sections that can be found in the contents. 

  3. The go to “SECTION” means to continue to check

going to the “section”. 

 

  4. The go through “SECTION” means to go through 

the “section” and then to go back to the place the go 
through was written. 

  5. BASIC ELECTRIC CIRCUITS: 

You should understand the basic theory of 
electricity. This includes the meaning of voltage, 
amps, ohms, and what happens in a circuit with an 
open or shorted wire. You should also be able to 
read and understand wiring diagrams. 

Check Trans Indicator 

Find CHECK TRANS indicator and verify if it is 

A. 

Flashing: Go to On-Board Diagnostic (OBD) 
System Check. 

B. Staying on: Go through “Check Trans” Check. 

C. Is never “ON” when the ignition key is turned on: Go 

through “Check Trans” Check 

D. Is “ON” during 3 seconds at ignition but “OFF” after: 

Normal operation. No DTC or malfunction. 

 

 

 

 

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TRANSMISSION CONTROL SYSTEM (AW30–40LE)  7A2-17 

Normal 

 

 
 
 

 

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Abnormal 

 

 
 
 
 

 

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On-Board Diagnostic (OBD) System Check

This test determines if the transmission or its input or 
output connections or sensors are failing. 

  1. Connect the Tech 2: Go through Tech 2 Operating.

  2. Turn on the ignition but not the engine. 

  3. Push “F0” on Tech 2 to see the Diagnostic Trouble 

Code (DTC): 

  4. Do you have a DTC? 

YES: write down all code numbers and do the DTC 
CHECK 

NO: the DTC can not help you find the problem. 

  1. Go through “Check Trans” Check 

  2. If it is flashing and the flash is 0.4 seconds “ON” 

and 0.4 seconds “OFF”, this means that you 
should have a DTC stored.  Please recheck go 
to On-Board Diagnostic (OBD) System Check
and if you find the same problem, replace the 
Transmission Control Module (TCM). 

 “Check Trans” Check 

  1. Indicator is “ON” during 3 seconds at ignition but it 

is “OFF” after the engine starts. The indicator is 
working normally go to On-Board Diagnostic 
(OBD) System Check. 

 

 

 

 

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