TSB-23-54-004

SUBJECT:
DIAGNOSTIC PROCEDURE CORRECTION FOR BATTERY
MANAGEMENT UNIT – SERVICE MANUAL REVISION
No:
TSB-23-54-004
DATE:
May 2023
MODEL: 2018-21 Outlander PHEV
CIRCULATE TO:
[ ] GENERAL MANAGER
[ X ] PARTS MANAGER
[ X ] TECHNICIAN
[ X ] SERVICE ADVISOR
[ X ] SERVICE MANAGER
[ X ] WARRANTY PROCESSOR
[ ] SALES MANAGER
PURPOSE
This TSB provides diagnostic procedure correction for the Battery Management Unit (BMU) in
the applicable Service Manual section.
AFFECTED VEHICLES
2018-2021 Outlander PHEV
AFFECTED SERVICE MANUAL
• 2018-2021 Outlander PHEV Service Manual, Group 54
PROCEDURE
Please use the following chart as a guide to replace the indicated pages in the affected Service
Manuals, Group 54, Battery Management Unit (BMU) and Main Drive Lithium-Ion Battery
Diagnostic Trouble Code Procedures.
Applicable manual
Pub. No.
2018 OUTLANDER
PHEV Service
Manual
MSCD-027B-2018
2019 OUTLANDER
PHEV Service
Manual
MSCD-027B-2019
2020 OUTLANDER
PHEV Service
Manual
MSCD-027B-2020
2021 OUTLANDER
PHEV Service
Manual
MSCD-027B-2021
Applicable Title
Contents
54Dc BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUMION BATTERY
└ DIAGNOSTIC TROUBLE CODE PROCEDURES
└ DTC P0AA6: LEAK DETECTION, P0AA9: LEAK SNS.
DETECTION CIRCUIT SHORT
Attached
Sheet 2
54Dc BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUMION BATTERY
└ DIAGNOSTIC TROUBLE CODE PROCEDURES
└ DTC P0AA8: LEAK SENSOR DETECTION CIRCUIT OPEN
54Dc BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUMION BATTERY
└ DIAGNOSTIC TROUBLE CODE PROCEDURES
└ DTC P0AA6: LEAK DETECTION, P0AA9: LEAK SNS.
DETECTION CIRCUIT SHORT
54Dc BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUMION BATTERY
└ DIAGNOSTIC TROUBLE CODE PROCEDURES
└ DTC P0AA8: LEAK SENSOR DETECTION CIRCUIT OPEN
Attached
Sheet 3
Attached
Sheet 4
Attached
Sheet 5
Copyright 2023, Mitsubishi Motors North America, Inc.
The information contained in this bulletin is subject to change. For the latest version of this document, go to the Mitsubishi
Dealer Link, MEDIC, or the Mitsubishi Service Information website (www.mitsubishitechinfo.com).
5/2/2023
1 of 5
(5302/MSB23M54501)
Attached sheet 2
54Dc-200
BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUM-ION BATTERY
DIAGNOSTIC TROUBLE CODE PROCEDURES 
FAIL-SAFE AND BACKUP FUNCTION

.
PROBABLE CAUSES
x Decrease of insulation resistance of high voltage
system components
x The sub-battery management unit [BMU (SUB)]
is failed.
x Malfunction of BMU (SUB) (malfunction of the
leakage sensor function inside the ECU)
x Estimating computing for the current capacity of
the battery is not performed.
x Automatic capacity measurement by the tester
and smoothing of cell voltage are prohibited.
.
FAIL-SAFE AND BACKUP FUNCTION

x Not available
DIAGNOSIS
Required Special Tools
x MB991658: Test harness
DANGER
When high voltage system components are serviced,
be sure to pull service plugs to shut down high voltage.
DANGER
When pulling service plugs, wear the specified protective equipment.

STEP 1. Using scan tool (M.U.T.-IIISE), check whether the
DTC is set. 
Check whether the DTC P0AA6 is set.

STEP 1. Using scan tool (M.U.T.-IIISE), check
whether the DTC is set.
Is only either one of DTC No. P0AA6 and No.
P0AA9 set?
Q:Is the DTC set?
YES : Go to Step 1-1.
NO : Go to Step 2.
STEP 1-1. Using scan tool (M.U.T.-IIISE), check
whether the DTC is set.
Check whether the DTC No. P0AA6 or No. P0AA9
is set.
・Wait 20 seconds after turning ON the
power supply mode of electric motor switch.
・Ready indicator is illuminated.
Q:Is the DTC set?
YES : Go to Step 2.
NO : Intermittent malfunction (Refer to GROUP
00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with
Intermittent Malfunctions).
5/2/2023
Q: Is the DTC set?
YES : Perform the troubleshooting.
NO : Go to Step 2.
STEP 2. Using scan tool (M.U.T.-IIISE), read the DTC.
(1) Turn on the power supply mode of the electric motor switch.
(2) Wait 20 seconds.
(3) Selector lever position indicator: P
NOTE: If the DTC is set with the power supply mode of
electric motor switch turned ON, an electric leak could occur
inside the main drive lithium-ion battery.
Q: Is the DTC set?
YES : Go to Step 3.
NO : Go to Step 10.
2 of 5
(5302/MSB23M54501)
Attached sheet 3
BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUM-ION BATTERY
DIAGNOSTIC TROUBLE CODE PROCEDURES 
54Dc-223
x The main drive lithium-ion battery ground fault
detector failed.
x Open circuits of main drive lithium-ion battery
ground fault detector circuit, short circuits to
ground, short circuits to power supply system or
damage; poor contact of connector.
x The sub-battery management unit [BMU (SUB)]
is failed.
.
FAIL-SAFE AND BACKUP FUNCTION
x Not available
.
PROBABLE CAUSES
x Ground fault of high voltage system component.
DIAGNOSIS
Required Special Tools
x MB991658: Test harness
DANGER
When pulling service plugs, wear the specified protective equipment.
STEP 1. Using scan tool (M.U.T.-IIISE), check whether the
DTC is set.
Check whether the DTC P0AA6 is set.
Q: Is the DTC set?
YES : Perform the troubleshooting.
NO : Go to Step 2. 
1-1. 
STEP 2. Measure the resistance at main drive lithium-ion
battery connector.
(1) Disconnect the connector No.D-34, and measure at the
wiring harness side.
(2) Check the resistance between the main drive lithium-ion
battery connector No.D-34 (terminal No.6) and body
ground.
OK: Continuity (2 : or less)
Q: Is the check result normal?
YES : Go to Step 3.
NO : Repair the connector(s) or wiring harness. Then go to
Step 6.
STEP 1-1. Using scan tool (M.U.T.-IIISE), check whether the DTC
P0AA8 is set.
Check whether the DTC P0AA8 is set.
Q:Is the DTC set?
YES : Go to Step 2.
NO : Intermittent malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection Service Points - How to Cope
with Intermittent Malfunctions ).

5/2/2023
3 of 5
(5302/MSB23M54501)
Attached sheet 4
54Dc-232
BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUM-ION BATTERY
DIAGNOSTIC TROUBLE CODE PROCEDURES 
FAIL-SAFE AND BACKUP FUNCTION

PROBABLE CAUSES
• Decrease of insulation resistance of high voltage
system components
• The sub-battery management unit [BMU (SUB)]
is failed.
• Malfunction of BMU (SUB) (malfunction of the
leakage sensor function inside the ECU)
• Estimating computing for the current capacity of
the battery is not performed.
• Automatic capacity measurement by the tester
and smoothing of cell voltage are prohibited.
FAIL-SAFE AND BACKUP FUNCTION

• Not available
DIAGNOSIS
Required Special Tools
• MB991223: Wiring harness set
• MB992006: Extra fine probe
• MB992355: Electric insulation tester
DANGER
When high voltage system components are serviced,
be sure to pull service plugs to shut down high voltage.
DANGER
When pulling service plugs, wear the specified protective equipment.
STEP 1. Using scan tool (M.U.T.-IIISE), check whether the
other DTC is set.
 STEP 1-2. Q: Is the DTC related to PHEV-ECU system set?
YES : Check PHEV-ECU system (Refer to GROUP 54Da Diagnostic Trouble Code Chart).
NO : Go to Step 2.

STEP 2. Using scan tool (M.U.T.-IIISE), check whether the
other DTC is set.
STEP 1. Using scan tool (M.U.T.-IIISE), check
Q: Is the DTC related to A/C compressor or electric
whether the DTC is set.
heater-ECU system set?
Is only either one of DTC No. P0AA6 and No. P0AA9
YES : Check A/C-ECU system (Refer to GROUP 55 set?
Troubleshooting - Diagnostic Trouble Code Chart
Q:Is the DTC set?
, ).
・Wait 20 seconds after turning ON the power

supply mode of electric motor switch.
・Ready indicator is illuminated
YES : Go to Step 1-1.
NO : Go to Step 1-2.
NO : Go to Step 3.
STEP 1-1. Using scan tool (M.U.T.-IIISE), check
whether the DTC is set.
Q:Check if the DTC is set in the PHEV-ECU.
YES : Go to Step 1-2.
NO : Intermittent malfunction (Refer to GROUP 00
- How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent
Malfunctions).
5/2/2023
4 of 5
(5302/MSB23M54501)
Attached sheet 5
BATTERY MANAGEMENT UNIT (BMU) AND MAIN DRIVE LITHIUM-ION BATTERY
DIAGNOSTIC TROUBLE CODE PROCEDURES 
Check Conditions
• BMU (SUB) power supply voltage is 8 volts to 16
volts.
• Time after above conditions satisfy is more than
3.5 seconds.
• Precheck signal status is on.
54Dc-261
FAIL-SAFE AND BACKUP FUNCTION
• Not available
PROBABLE CAUSES
Judgment Criterion
• Isolation counter 1 is less than 2 times for 25.4
seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to OBD-II Drive Cycle - Pattern 1.
• Ground fault of high voltage system component.
• The main drive lithium-ion battery ground fault
detector failed.
• Open circuits of main drive lithium-ion battery
ground fault detector circuit, short circuits to
ground, short circuits to power supply system or
damage; poor contact of connector.
• The sub-battery management unit [BMU (SUB)]
is failed.
DIAGNOSIS
Required Special Tools
• MB991658: Test harness
DANGER
When high voltage system components are serviced,
be sure to pull service plugs to shut down high voltage before servicing.
DANGER
When pulling service plugs, wear the specified protective equipment.
 STEP 1-1.
STEP 1. Measure the resistance at main drive lithium-ion
battery connector.
(1) Disconnect the D-34 main drive lithium-ion battery
connector, and measure at the wiring harness side.
(2) Check the resistance between the D-34 main drive
lithium-ion battery connector (terminal No.6) and body
ground.
OK: Continuity exist (2 Ω or less)
Q: Is the check result normal?
YES : Go to Step 2.
NO : Repair the connector(s) or wiring harness. Then go to
Step 3.
STEP 1. Using scan tool (M.U.T.-IIISE), check whether the DTC
P0AA8 is set.
Check whether the DTC P0AA8 is set.
Q:Is the DTC set?
YES : Go to Step 1-1.
NO : Intermittent malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection Service Points - How to Cope
with Intermittent Malfunctions ).

5/2/2023
5 of 5
(5302/MSB23M54501)