2004 MITSUBISHI ENDEAVOR diagnosis

DTC U1120: FAILURE INFORMATION ON POWERTRAIN CONTROL MODULE (RELATED TO ENGINE)TROUBLE JUDGMENT The A/C-ECU receives engine control system-related signal from the powertrain
control module by the CAN bus lines. If a fail-safe related data is contained in the
signal from the powertrain control module, DTC U1120 will be stored. TECHNICAL DESCRIPTION (COMMENT)
CURRENT TROUBLE
The wiring harness wire or connectors may have loose, corroded, or damage
terminals, or terminals pushed back in the connector, the powertrain control
module, or the A/C-ECU may be defective.
PAST TROUBLE
If DTC U1120 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.
CAUTION: If DTC U1120 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.
CAUTION: The engine control system- related DTC may be set
when DTC U1120 is set (For details refer to
INTERSYSTEM AFFILIATED DTC REFERENCE
TABLE
). Diagnose the engine control system first
when the engine control system- related DTC is set.
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.

2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor

TROUBLESHOOTING HINTS
Malfunction of the A/C-ECU. Malfunction of the powertrain control module.
DIAGNOSIS REQUIRED SPECIAL TOOLS:

MB991223: Harness Set 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)
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

1. Connect scan tool MB991958 to the data link connec
tor.
In this case, refer to HOW TO USE TROUBLESHOOTING/ INSPECTION SERVICE POINTS
). 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 communication-linked ECUs (Refer to EXPLANATION
ABOUT THE MUT
-III CAN BUS DIAGNOSIS
).
CAUTION: To prevent damage to scan tool (MUT-III), always
turn the ignition switch to the "LOCK" (OFF)
position before connecting or disconnecting
scan tool (MUT-III).

2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor

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 line (Refer to
EXPLANATION ABOUT THE
MUT
-III CAN BUS DIAGNOSIS
, DIAGNOSIS < VEHICLES
WITHOUT ADVANCED AIR BAG
or
DIAGNOSIS WITH ADVANCED AIR BAG>
.)
STEP 2. Using scan tool MB991958, read the powertrain control module
diagnostic trouble code.

2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor

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
HOW TO USE TROUBLESHOOTING/ INSPECTION
SERVICE POINTS
).
NO:
Replace the A/C-ECU. On completion, check that the DTC is not
reset.
SYMPTOM CHART
CAUTION: During diagnosis, a DTC code associated with other
system may be set when the ignition switch is turned
on with connector(s) disconnected. On completion,
confirm all systems for DTC code(s). If DTC code(s)
are set, erase them all.

2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor

Fig. 114: Heater And A/C System Symptom Chart

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

SYMPTOM PROCEDURES INSPECTION PROCEDURE 1: WHEN THE IGNITION SWITCH IS "ON", THE A/C DOES NOT OPERATE TECHNICAL DESCRIPTION (COMMENT) The blower system or the compressor system may be defective if there is no cool air
coming from the vents. TROUBLESHOOTING HINTS
Malfunction of blower motor Malfunction of A/C compressor
DIAGNOSIS Check that the blower motor operation when the blower switch is moved to the
"HI" position.


2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor

1. Turn the ignition switch to the "ON" position.
2. Turn the blower switch to the "HI" position Q: Does the blower motor operate when the blower switch is moved to the
"HI" position?

YES:
Refer to
INSPECTION PROCEDURE 4 WHEN THE A/C IS
OPERATING, TEMPERATURE INSIDE THE PASSENGER COMPARTMENT DOES NOT DECREASE (COOL AIR NOT EMITTED)
.
NO:
Refer to
INSPECTION PROCEDURE 5 BLOWER FAN AND
MOTOR DO NOT TURN
.
INSPECTION PROCEDURE 2: WHEN THE AIR OUTLET CHANGEOVER CONTROL KNOB IS MOVED TO
DEFROSTER OR DEFROSTER/FOOT POSITION, THE A/C OR THE INSIDE/OUTSIDE AIR CHANGEOVER
DAMPER MOTOR DOES NOT OPERATE TECHNICAL DESCRIPTION (COMMENT) If the outside/inside air selection damper control motor does not operate normally,
the inside/outside air changeover damper motor system may be defective. TROUBLESHOOTING HINTS
Malfunction of the A/C-ECU Malfunction of the outside/inside air selection damper control motor Damaged harness wires or connectors
DIAGNOSIS Check operation of the outside/inside air selection damper control motor.

1. Turn the ignition switch to the "ON" position.
2. Outside/inside air selection damper motor switch: This is used to switch from
the inside air to outside air or vice versa.
3. Check to see that the outside/inside air selection damper motor operates
normally.
Q: D
oes
ou
tside/
inside air
selection dam
per contr
ol m
otor wo
rk n
ormall
y?

2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor

Fig. 118: Identifying Connectors C
-211 And C
-215

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

CIRCUIT OPERATION If the outside/inside air selection damper control motor does not operate normally,
the outside/inside air selection damper control motor system may be defective. TROUBLESHOOTING HINTS
Malfunction of the outside/inside air selection damper control motor Malfunction of the A/C-ECU Damaged harness wires or connectors
DIAGNOSIS REQUIRED SPECIAL TOOL:

MB991223: Test Harness Set

2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor

relay system may be defective. TROUBLESHOOTING HINTS
Improper amount of refrigerant Malfunction of the air thermo sensor Malfunction of the ambient air temperature sensor Malfunction of the A/C pressure sensor Malfunction of the A/C compressor clutch relay Malfunction of the A/C refrigerant temperature switch Malfunction of the air conditioning compressor clutch Malfunction of the A/C-ECU Malfunction of the PCM Damaged harness wires or connectors
DIAGNOSIS REQUIRED SPECIAL TOOLS:

MB991223: Test Harness Set 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)
STEP 1. Check the defogger and outside/inside air selection damper
control motor operation.

Q: Do the defogger and outside/inside air selection damper control motor
work normally?

YES:
Go to Step 2.
NO:
Refer to
INSPECTION PROCEDURE 10 MALFUNCTION OF
THE A/C
-ECU POWER SUPPLY SYSTEM
.

2004 Mitsubishi Endeavor LS
2004 HVAC Heater Air Conditioning, Ventilation - Endeavor