BULLETIN NUMBER:
IB21-X-002

IMPORTANT SERVICE
INFORMATION FOR:
 SERVICE MANAGER
 SERVICE ADVISOR
 TECHNICIAN
 PARTS DEPARTMENT
 WARRANTY PERSONNEL

ISSUE DATE:
MARCH 2021
GROUP:
MISCELLANEOUS

INTRODUCTION TO NQR NRR Gas
AFFECTED VEHICLES


2022 MY Isuzu NQR and NRR vehicles with 6.0L gasoline
engine
INFORMATION

The information below is provided to help technicians better understand common
vehicle operations that may be incorrectly perceived as an issue. Additionally,
diagnostic scan tool connection requirements are outlined for easier technician
diagnosis.

Possible Complaint

Normal Condition Description

Harsh shifting in all gears
during initial operation.

The Allison transmission will operate in “learning mode” for
the first 30 – 50 miles of operation. Shift quality will
improve after this initial period.

Transmission holds first
gear longer.

Due to different mechanical ratios, the Allison transmission
may remain in 1st gear for a longer time before making the
shift to 2nd gear when compared to the 6L90 transmission
utilized in previous model years.

Gear Shift Lever requires
high effort to move through
the Gear Selection Range

The shift detents on the Allison transmission are stronger
than the 6L90 transmission utilized in previous model
years.

Sound from Starter area
after Engine is started

The design of this vehicle keeps the starter motor
momentarily engaged after the engine starts. This will
create a brief whirring noise, which is normal.

The Diagnostic Trouble
Codes (DTC) are
unfamiliar.

PTO will not engage while
the vehicle is moving.
Are any Special Service
Tools needed to service
the rear disc brakes and
rear axle hubs?

The ECM and Powertrain Interface Module (PIM) utilize a
SPN/FMI DTC structure. The IDSS DTC display for this
vehicle will consist of a two to four digit number, followed by a
dash, and then another one to two digit number. A written
definition of the DTC will also be displayed. (Example: 367317 System Voltage Low – Main Relay)
Refer to the Workshop Manual for more information.
The PTO can only be utilized while the vehicle is stationary.

Special Service Tools Unique to this vehicle:





J-8433 Two Jaw Puller
J- 24427 Bearing Cup Installer
J-43412 Bearing Cup Installer
OTC 8013 Threaded Adapter

Special Service Tools already in inventory:




J-35012 Hub Bearing Nut Adjuster
J-35013 Rear Hub Puller
J-35030 Puller Pilot

IMPORTANT: For a picture and description of each tool,
refer to the Isuzu Special Service Tool website https://www.isuzutruckservice.com/bosch_sso.php

Cannot locate the Engine
Serial Number

The correct engine serial number is 10 characters long and is
stamped on the left rear of the engine block where the
cylinder head is mounted. (See Figure 1.)

Figure 1

An engine serial number is also located on the Emissions
Control Label on top of the intake manifold. (See Figure 2.)
This is a secondary number and should only be used after
verifying the engine serial number shown in Figure 1.

Figure 2
ISUZU DIAGNOSTIC SYSTEMS SERVICE (IDSS) COMMUNICATION
No.

Description

1.

The metal case
IDSS interface will
NOT communicate
with the NQR/NRR
6.0L gas engine
ECUs.

The IDSS Tablet
will communicate
with all onboard
ECUs.

2.

ECUs

ECM
TCM

The interface cable
PIM
with double red
ends is required for
Electronic
complete
Brake Control
communication
Module
with all onboard
(EBCM)
ECUs when using
this device.

IDSS Interface/Scan Tool

The plastic case
IDSS interface
will communicate
with all onboard
ECUs.

ECM
TCM

3.

The interface
cable with
double red ends
is required for
complete
communication
with all onboard
ECUs when
using this device.
The MX2-TW
IDSS interface
will communicate
with all onboard
ECUs.

4.

5.

The interface
cable with a blue
end is required
for complete
communication
with all onboard
ECUs when
using this device.
The DLC
interface cable
with double red
ends is required
for complete
communication
with all onboard
ECUs when
using 2 and 3
above
Do not use this
cable w/new
IDSS interface
module (MX2TW)

PIM
Electronic Brake
Control Module
(EBCM)

ECM
TCM
PIM
Electronic Brake
Control Module
(EBCM)

ECM
TCM
PIM
Electronic Brake
Control Module
(EBCM)

6.

7.

The DLC
interface cable
with a blue end
is required for
complete
communication
with all onboard
ECUs when
using the MX2TW device.

The USB
interface Y-cable
is also required
for complete
communication
with all onboard
ECUs when
using any IDSS
device.

ECM
TCM
PIM
Electronic Brake
Control Module
(EBCM

ECM
TCM
PIM
Electronic Brake
Control Module
(EBCM)

IDSS HDOBD
Adapter Cable

8.

This cable can
be used without
the Y-cable if
ABS data is not
required.
Remove the Ycable when
programming the
ECM.

ECM

9.

IDSS Software will only display existing TCM DTCs. All other TCM data can only
be retrieved using Allison DOC Software. IDSS currently does not support Allison
DOC Software.

This illustration displays three of the cables described above linked in series to
obtain complete communications with all onboard ECU’s.
IDSS Connections