Mitsubishi Lancer (4A9 engine). Manual - part 61

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-97

35A 

−Brake Pedal ).

ACX00671AE

No continuity

Continuity

4 mm

(2) Connect the circuit tester (

Ω range) to the stop 

lamp switch connector terminals No.1 and 2.

(3) When no continuity is detected with the plunger 

pressed from the edge of the outer case by the 
dimension shown in the figure and when 
continuity is detected with the plunger released, 
the stop lamp switch is in good condition.

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Replace the stop lamp switch (Refer to 
GROUP 35A 

−Brake Pedal ), and then go to 

Step 9.

STEP 6. Brake drag check
Check the brake system for drag.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the brake drag, and then go to Step 
9.

STEP 7. Brake booster check
Refer to GROUP 35A 

− On-vehicle Service/Brake 

Booster Operation Check .

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Replace the brake booster (Refer to 
GROUP 35A 

− Master Cylinder Assembly 

and Brake Booster  <Except 4B11>,  
<4B11>), and then go to Step 9.

STEP 8. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is the diagnosis code No. C121E set?

YES : 

Replace the hydraulic unit (integrated with 

ASC-ECU) (Refer to 

P.35C-185

). Then go 

to Step 9.

NO : 

The trouble can be an intermittent 
malfunction (Refer to GROUP 00 

− How to 

Use Troubleshooting/How to Cope with 
Intermittent Malfunctions ).

STEP 9. Check whether the diagnosis code is 
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.C121E set?

YES : 

Return to Step 1.

NO : 

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-98

Code No. C1000 Abnormality in stop lamp switch circuit

REAR 
COMBINATION 
LAMP 
(STOP: LH)

REAR 
COMBINATION 
LAMP 
(STOP: RH)

HIGH-MOUNTED 
STOP LAMP

STOP LAMP 
SWITCH

ETACS-
ECU

Stop Lamp Switch 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

NOTE

:
:

LANCER 
LANCER SPORTBACK 

ACB02571

AC612705

Connectors: C-24, C-31 <LHD>

IX

C-24

C-31

AC612711

Connector: C-24 <RHD>

AD

AC612710

Connectors: C-31 <RHD>

EQ

AC607219

AH

Connectors: C-304, C-312 <LHD>

C-312

C-304

AC607229AH

Connectors: C-304, C-312 <RHD>

C-304

C-312

AC612723

BU

Connectors: D-12, D-17

D-17

D-12

AC612744 BG

Connectors: F-08, F-11, F-23 <LANCER>

F-08

F-23

F-11(GR)

AC801775 BL

F-08

F-11

F-23

Connectors: F-08, F-11, F-23 
<LANCER SPORTBACK>

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-99

CAUTION

• If there is any problem in the CAN bus lines, 

an incorrect diagnosis code may be set. Prior 
to this diagnosis, diagnose the CAN bus lines 
(Refer to GROUP 54C 

− CAN Bus Diagnostics 

Table ).

• Whenever ECU is replaced, ensure that the 

CAN bus lines are normal.

OPERATION
ETACS-ECU sends the ON signal generated when 
the brake pedal is depressed and OFF signal gener-
ated when it is released to ASC-ECU via the CAN 
bus lines.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set in the following case.

• When the vehicle has run for a long time with the 

stop lamp switch turned ON.

• When the OFF status of the stop lamp switch 

does not match the vehicle attitude

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-100

PROBABLE CAUSES

• Improper adjustment of stop lamp switch installa-

tion position

• Stop lamp switch malfunction

• Damaged wiring harness and connectors

• Malfunction of ETACS-ECU

• ASC-ECU malfunction

DIAGNOSTIC PROCEDURE

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

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

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

− CAN Bus Diagnostics Table .) On 

completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting 
CAN bus lines

Q: Is diagnosis code No.C1000 set?

YES : 

Go to Step 3.

NO : 

This diagnosis is complete.

STEP 3. Battery check
Refer to GROUP 54A 

− Battery Test .

Q: Is the battery in good condition?

YES : 

Go to Step 4.

NO : 

Charge or replace the battery, and go to 
Step 15.

STEP 4. Stop lamp operation check
Check the stop lamp operation when the brake pedal 
is depressed. Check that all the stop lamp illuminates 
when the brake pedal is depressed and that it goes 
out when the brake pedal is released.

OK:

When the brake pedal is released: OFF
When the brake pedal is depressed: Illumi-

nates

Q: Is the check result normal?

YES : 

Go to Step 15.

NO : 

Go to Step 5.

STEP 5. Check for stop lamp switch installation
Refer to GROUP 35A 

− On-vehicle Service/Brake 

Pedal Check and Adjustment .

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Install the stop lamp switch correctly. (Refer 
to GROUP 35A 

− On-vehicle Service/Brake 

Pedal Check and Adjustment .) Then go to 
Step 19.

STEP 6. Stop lamp switch continuity check
(1) Remove the stop lamp switch. (Refer to GROUP 

35A 

− Brake Pedal .)

ACX00671AE

No continuity

Continuity

4 mm

(2) Connect the circuit tester (

Ω range) to the stop 

lamp switch connector terminals No. 1 and 2.

(3) When no continuity is detected with the plunger 

pressed from the edge of the outer case by the 
dimension shown in the figure and when 
continuity is detected with the plunger released, 
the stop lamp switch is in good condition.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Replace the stop lamp switch. (Refer to 
GROUP 35A 

− Brake Pedal .) Then go to 

Step 19.

STEP 7. ETACS-ECU fuse No.2 check

Q: Is the check result normal?

YES : 

Go to Step 11.

NO : 

Go to Step 8.