2005 MITSUBISHI 380 Workshop Manual

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-28
DTC B1041, B1042: Air Mixing Damper Control Motor and Potentiometer (Potentiometer system)
.
DTC SET CONDITION
DTC B1041 or B1042 is set if there is an open or
short circuit in the potentiometer input circuit, or if
there is an open circuit in the power circuit or
earth circuit.
.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
The A/C-ECU, the air mixing damper control
motor and potentiometer, or connector(s) or wir-
ing between the two may be defective.Past trouble
If DTC B1041 or B1042 is stored as a past trou-
ble, carry out diagnosis with particular emphasis
on wiring and connector(s) between the A/C-ECU
and the air mixing damper control motor and
potentiometer. 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.
TROUBLESHOOTING HINT
Malfunction of connector.
Malfunction of the harness.
Malfunction of the air mixing damper control
motor and potentiometer.
Malfunction of the A/C-ECU.
Refer to component locations GROUP-70
Refer to configuration diagrams GROUP-80
Refer to circuit diagrams GROUP-90
DIAGNOSIS
Required Special Tool:
: Diagnostic 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)

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-29
STEP 1. Using diagnostic tool , diagnose the CAN bus line.
Use diagnostic tool to diagnose the CAN bus lines.
(1) Connect diagnostic tool to the data link connector.
(2) Turn the ignition switch to "ON" position.
(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?
YES : Go to Step 2.
NO : Repair the CAN bus lines. (Refer to GROUP 54C,
Diagnosis-Can Bus Diagnostic Chart P.54C-405).
Then go to Step 7.
STEP 2. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is set.
Q: Is the check result satisfactory?
YES : It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunctions P.00-14.
NO : Go to Step 3.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-30
STEP 3. Using diagnostic tool , check data list item 63: Air
mix potentiometer.
To prevent damage to diagnostic tool , always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting diagnostic tool .
(1) Connect diagnostic tool to the data link connector.
(2) Start the engine.
(3) Set diagnostic tool to the data reading mode for item 63: Air
mix potentiometer.
Check that the set position of the heater control matches
the displayed position on the diagnostic tool.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor within the specified range?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Go to Step 4.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-31
STEP 4. Check A/C-ECU connector C-15, C-16 and air
mixing damper control motor and potentiometer connector
C-105 for loose, corroded or damaged terminals, or
terminals pushed back in the connector.
Q: Are A/C-ECU connector C-15, C-16 and air mixing
damper control motor and potentiometer connector
C-105 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2. Then go
to Step 7.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-32
STEP 5. Check the wiring harness between A/C-ECU
connectors C-15 (terminals 16 and 20), C-16 (terminal 29)
and air mixing damper control motor and potentiometer
connector C-105 (terminals 5, 7 and 3).
Q: Are the wiring harness between A/C-ECU connector
C-15 (terminals 16 and 20), C-16 (terminal 29) and air
mixing damper control motor and potentiometer
connector C-105 (terminals 5, 7 and 3) in good
condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-33
STEP 6. Check the air mixing damper control motor and
potentiometer.
Do not apply battery voltage when the damper is in the
MAX COOL or MAX HOT position.
(1) Operate the air mixing damper control motor as described
in the table below.
(2) Measure the resistances between connector terminals 3
and 5, and between 3 and 7, while the air mixing damper
control motor is running. The resistances should change
gradually within the standard value.
Standard value: 1.7 (MAX HOT)
5.0 (MAX COOL)
k
Q: Are the air mixing damper control motor and
potentiometer in good condition?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Replace the air mixing damper control motor and
potentiometer. Then go to Step 7. LEVER POSITION BATTERY
CONNECTIONLEVER
OPERATION
At the MAX COOL
position
Connect
terminal 2 to the
positive battery
terminal
Connect
terminal 1 to the
negative battery
terminalThe lever moves
from the MAX
COOL position to
the MAX HOT
position
At the MAX HOT
position
Connect
terminal 1 to the
positive battery
terminal
Connect
terminal 2 to the
negative battery
terminalThe lever moves
from the MAX HOT
position to the MAX
COOL position

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-34
STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect diagnostic tool to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : The procedure is complete.
NO : Return to Step 1.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-35
DTC B1045: Air mixing damper control motor and potentiometer (activating system failure)
.
DTC SET CONDITION
If the air mixing damper control motor does not
work normally, DTC No.B1045 will be set.
.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
The A/C-ECU, the air mixing damper control
motor and potentiometer, or connector(s) or wir-
ing between the two may be defective.Past trouble
If DTC B1045 is stored as a past trouble, carry
out diagnosis with particular emphasis on wiring
and connector(s) between the A/C-ECU and the
air mixing damper control motor and potentiome-
ter. 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.
TROUBLESHOOTING HINT
Malfunction of connector.
Malfunction of the harness.
Malfunction of the air mixing damper control
motor and potentiometer.
Malfunction of the A/C-ECU.
Refer to component locations GROUP-70
Refer to configuration diagrams GROUP-80
Refer to circuit diagrams GROUP-90