Mitsubishi Galant 9G. Manual — part 243

MANUAL A/C DIAGNOSIS

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DTC U1100: Powertrain Control Module Time-out (Related to Engine)

CAUTION

If DTC U1100 is set in the A/C-ECU, diagnose the
CAN main bus line.

CAUTION

Whenever the ECU is replaced, ensure that the
communication circuit is normal.

.

TROUBLE JUDGMENT

The A/C-ECU receives engine control sys-
tem-related signal from the powertrain control mod-
ule. If the ECU cannot receive the signal, DTC
U1100 will be set.

.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

• Connector(s) or wiring harness in the CAN bus

lines between the powertrain control module and
the A/C-ECU, the power supply system to the
powertrain control module, the powertrain control
module itself, or the A/C-ECU may be defective.

Past trouble

• If DTC U1100 is stored as a past trouble, carry

out diagnosis with particular emphasis on wiring
and connector(s) in the CAN bus line between
the A/C-ECU and the powertrain control module,
and the power supply system to the powertrain
control module. If the connectors and wiring are
normal, and obviously the ECU is the cause of
the trouble, replace the ECU. If in doubt, do not
replace the ECU.
NOTE: For a past trouble, you cannot find it by
the scan tool CAN bus diagnostics even if there is
a failure in CAN bus lines. In this case, refer to
GROUP 00, How to Use Troubleshooting/Inspec-
tion Service Points

−

How to Cope with Intermit-

tent Malfunctions

P.00-14

) and check the CAN

bus lines. You can narrow down the possible
cause of the trouble by referring to the DTC,
which is set regarding the CAN communica-
tion-linked ECUs (Refer to GROUP 54C, Expla-
nation about the scan too CAN bus diagnostics

P.54C-6

).

.

TROUBLESHOOTING HINTS

• Powertrain control module failed

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN

communication system)

MANUAL A/C DIAGNOSIS

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STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.

CAUTION

To prevent damage to scan tool (MUT-III), always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool (MUT-III).
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO : Repair the CAN bus lines (Refer to GROUP 54C,

precautions on how to repair the can bus lines

P.54C-5

).

STEP 2. Using scan tool MB991958 read the powertrain
control module diagnostic trouble code.
Check whether an engine and automatic transmission DTCs
are set or not.
(1) Turn the ignition switch to the "ON" position.
(2) Check for engine and automatic transmission DTCs.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : Go to Step 3.
NO : Diagnose the powertrain control module (Refer to

GROUP 13A, Diagnostic Trouble Code

P.13A-33

<2.4L> or GROUP 13B, Diagnostic Trouble Code

P.13B-34

<3.8L>).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

55A-50

STEP 3. Using scan tool MB991958, check for any
diagnostic trouble code.
Check if a DTC, which relates to CAN communication-linked
systems below, is set.

• Combination meter

DTC indicating a time-out error related to the engine or
automatic transmission control system

• ETACS-ECU

DTC indicating a time-out error related to the engine or
automatic transmission control system

(1) Turn the ignition switch to the "ON" position.
(2) Check for a DTC related to the relevant system.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : Go to Step 5.
NO : Go to Step 4.

STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : A poor connection, open circuit or other intermittent

malfunction is present in the lines between the
powertrain control module and the A/C-ECU (Refer to
GROUP 00E, Harness Connector Inspection

P.00E-2

.)

NO : Replace the powertrain control module. On

completion, check that the DTC is not reset.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MANUAL A/C DIAGNOSIS

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STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?

YES : A poor connection, open circuit or other intermittent

malfunction is present in the lines between the
powertrain control module and the A/C-ECU (Refer to
GROUP 00E, Harness Connector Inspection

P.00E-2

.)

NO : Replace the A/C-ECU. On completion, check that the

DTC is not reset.

DTC U1111: Multi-Center Display Unit (Middle Grade Type) Time-out

CAUTION

If DTC U1111 is set in the A/C-ECU, diagnose the
CAN main bus line.

CAUTION

Whenever the ECU is replaced, ensure that the
communication circuit is normal.

.

TROUBLE JUDGMENT

The A/C-ECU receives signals from the multi-center
display unit (middle grade type). If the ECU cannot
receive the signal related to the multi-center display
unit, DTC U1111 will be set.

.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

• Connector(s) or wiring harness in the CAN bus

lines between the A/C-ECU and the middle-grade
multi-center display unit, the power supply sys-
tem to the display unit, the display unit itself, or
the A/C-ECU may be defective.

Past trouble

• When DTC U1111 is set as a past trouble, carry

out diagnosis with particular emphasis on con-
nector(s) or wiring harness in the CAN bus lines
between the A/C-ECU and the middle-grade
multi-center display unit, the power supply sys-
tem to the display unit. If the connectors and wir-
ing are normal, and obviously the ECU or the
middle-grade multi-center display is the cause of
the trouble, replace the ECU or the middle-grade
multi-center display. If in doubt, do not replace
the ECU or the display unit.
NOTE: For a past trouble, you cannot find it by
the scan tool CAN bus diagnostics even if there is
a failure in the CAN bus lines. In this case, refer
to GROUP 00, How to Use Troubleshoot-
ing/Inspection Service Points

−

How to Cope with

Intermittent Malfunctions

P.00-14

.) and check the

CAN bus lines. You can narrow down the possi-
ble cause of the trouble by referring to the DTC,
which is set regarding the CAN communica-
tion-linked ECUs (Refer to GROUP 54C

−

Expla-

nation about the scan tool CAN bus diagnostics

P.54C-6

).

.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827