Mitsubishi Lancer (4A9 engine). Manual - part 286

AC612706

Connectors: C-60, C-147 <LHD>

BP

C-60 (B)

C-147

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-25

COMMENTS ON TROUBLE SYMPTOM
This code will be set when the A/C control panel is 
faulty.

PROBABLE CAUSES

• Malfunction of the heater control panel

• Damaged wiring harness or connectors

• Malfunction of the heater control unit

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-147 heater control 
panel connector and C-60 heater control unit 
connector

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the connector.

STEP 2. Check the wiring harness between C-147 
heater control panel connector terminal No. 9 
and C-60 heater control unit connector terminal 
No. 9.

• Check the heater control panel signal line for 

open or short circuit.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the wiring harness.

STEP 3. Check whether the diagnosis code is 
reset.
Replace the heater control panel, and erase the 
diagnosis code. Then check that no diagnosis code 
is being set.

Q: Is the diagnosis code set?

YES : 

Replace the heater control unit.

NO : 

The trouble can be an intermittent 
malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction ).

Code No. B2214: Control panel failure <Vehicles with A/C>

A/C Control Panel Circuit

A/C-ECU

A/C
CONTROL
PANEL

CPU

INTERFACE
CIRCUIT

Wire colour code 
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue 
BR : Brown     O : Orange     GR : Grey     R : Red     P : Pink     V : Violet     PU : Purple     SI : Silver

ACA00799

AC612706

Connectors: C-15, C-119 <LHD>

AE

C-15 (B)

C-119

AC612710

Connector: C-15 <RHD>

AS

C-15 (B)

AC612711

Connector: C-119 <RHD>

AG

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-26

COMMENTS ON TROUBLE SYMPTOM
This code will be set when the A/C control panel is 
faulty.

PROBABLE CAUSES

• Malfunction of the A/C control panel

• Damaged wiring harness or connectors

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-119 A/C control 
panel connector and C-15 A/C-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the connector.

STEP 2. Check the wiring harness between C-119 
A/C control panel connector terminal No. 9 and 
C-15 A/C-ECU connector terminal No. 9.

• Check the A/C control panel signal line for open 

or short circuit.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the wiring harness.

STEP 3. Check whether the diagnosis code is 
reset
Replace the A/C control panel, and erase the diagno-
sis code. Then check that no diagnosis code is being 
set.

Q: Is the diagnosis code set?

YES : 

Replace the A/C-ECU.

NO : 

This diagnosis is complete.

Code No.U1415: Coding Not Completed

CAUTION

If diagnosis code No. U1415 is set in the A/C-
ECU, always diagnose the CAN bus lines.

CAUTION

Before replacing the ECU, ensure that the com-
munication circuit is normal.
TROUBLE JUDGMENT
The A/C-ECU receives vehicle information-related 
signals from the ETACS-ECU via the CAN bus lines. 
If the ECU receives an incorrect global coding data 
or cannot receive any coding data when the ignition 
switch is turned on and the coding is complete, diag-
nosis code U1415 will be set.

PROBABLE CAUSES

• Damaged wiring harness or connectors

• Malfunction of the ETACS-ECU

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2

NO : 

Repair the CAN bus lines. (Refer to GROUP 
54C 

− Troubleshooting ). On completion, go 

to Step 6.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-27

STEP 2. M.U.T.-III other system diagnosis code
Check whether the ETACS-related diagnosis code is 
set.

Q: Is the diagnosis code set?

YES : 

Diagnose the ETACS-ECU. Refer to 

NO : 

Go to Step 3

STEP 3. M.U.T.-III other system diagnosis code
Check if a diagnosis code, which relates to the CAN 
communication-linked systems below, is set.

• WCM <Vehicles with WCM>

B2204: Coding data unmatched

• KOS <Vehicles with KOS>

B2204: Coding data unmatched

Q: Is the diagnosis code set?

YES : 

Go to Step 4

NO : 

Go to Step 5

STEP 4. Check whether the diagnosis code is 
reset.
Recheck if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the ETACS-ECU, and then go to 

Step 6.

NO : 

A poor connection, open circuit or other 
intermittent malfunction in the CAN bus line 
between the ETACS-ECU and the A/C-ECU 
(Refer to GROUP 00 

− How to Cope with 

Intermittent Malfunction ).

STEP 5. Check whether the diagnosis code is 
reset.
Recheck if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the A/C-ECU, and then go to Step 

6.

NO : 

A poor connection, open circuit or other 
intermittent malfunction in the CAN bus line 
between the ETACS-ECU and the A/C-ECU 
(Refer to GROUP 00 

− How to Cope with 

Intermittent Malfunction ).

STEP 6. Check whether the diagnosis code is 
reset.
Recheck if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Return to Step 1.

NO : 

The procedure is complete.

Code No. U0019: Bus off (CAN-B)

CAUTION

If diagnosis code No.U0019 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
If the A/C-ECU ceases communicating once (i.e. bus 
off) and then returns to it, the A/C-ECU will not com-
municate for three minutes immediately after that 
point. This three-minute period is called "Penalty 
mode." Immediately after the A/C-ECU returns to 
communication, the diagnosis code is set.

COMMENTS ON TROUBLE SYMPTOM
The wiring harness wire or connectors may have 
loose, corroded, or damage terminals, or terminals 
pushed back in the connector, or the A/C-ECU may 
be defective.

PROBABLE CAUSES

• Damaged wiring harness or connectors

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-28

YES : 

Go to Step 2

NO : 

Repair the CAN bus lines (Refer to GROUP 
54C 

− Troubleshooting ). On completion, go 

to Step 3.

STEP 2. M.U.T.-III diagnosis code.
Recheck if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the A/C-ECU, and then go to Step 

3. 

NO : 

If a trouble is solved, it is determined that 
there is an intermittent malfunction such as 
poor engaged connector(s) or open circuit 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction ).

STEP 3. M.U.T.-III diagnosis code
Recheck if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Return to Step 1.

NO : 

The procedure is complete.

Code No. U0141: ETACS-ECU CAN time-out

CAUTION

If diagnosis code No.U0141 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 air conditioner operation-
related signal from the ETACS-ECU via the CAN bus 
lines. If the A/C-ECU can not receive the air condi-
tioner operation-related signal at all on the ETACS-
ECU, diagnosis code No.U0141 will be set.

COMMENTS ON TROUBLE SYMPTOM

Current trouble

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

lines between the ETACS-ECU and the A/C-
ECU, the power supply system to the ETACS-
ECU, the ETACS-ECU itself, or the A/C-ECU 
may be faulty.

Past trouble

• Carry out diagnosis with particular emphasis on 

connector(s) or wiring harness in the CAN bus 
lines between the ETACS-ECU and the A/C-
ECU, and the power supply system to the 
ETACS-ECU. For diagnosis procedures, refer to 
"How to treat past trouble" (Refer to GROUP 00 

− 

How to Treat Past Trouble ).

NOTE: For a past trouble, you can not find it by the 

M.U.T.-III CAN bus diagnostics even if there is 
any failure in CAN bus lines. In this case, refer to 
GROUP 00, How to Cope with Intermittent Mal-
function  and check the CAN bus lines. You can 
narrow down the possible cause of the trouble by 
referring to the diagnosis code, which is set 
regarding the CAN communication-linked ECUs 
(Refer to GROUP 54C 

−

 CAN Bus Line Diagnos-

tic Flow ).

CAUTION

If the ignition switch is turned on without starting 
the engine and then three minutes pass, the A/C-
ECU may store U0141 as past trouble.

PROBABLE CAUSES

• Damaged wiring harness or connectors

• Malfunction of the ETACS-ECU 

• Malfunction of the A/C-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2

NO : 

Repair the CAN bus lines (Refer to GROUP 
54C, Troubleshooting ). On completion, go 
to Step 6.

STEP 2. M.U.T.-III other system diagnosis code
Check whether the ETACS-related diagnosis code is 

set.

Q: Is the diagnosis code set?