Mitsubishi Lancer Evolution X. Manual - part 171

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-149

DIAGNOSIS

Required Special Tools:

• MB991958 Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)
• MB991827 M.U.T.-III USB Cable
• MB991910 M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
lines.
Using scan tool MB991958, 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 Diagnosis table 

P.54C-15

.) On completion, 

go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C1000 set?

YES : Go to Step 3.
NO :  This diagnosis is complete.

STEP 3. Battery check
Refer to GROUP 54A − Battery Test 

P.54A-9

.

Q: Is the battery in good condition?

YES : Go to Step 4.
NO :  Charge or replace the battery, and the go to Step 16.

STEP 4. Stoplight operation check
Check the stoplight operation when the brake pedal is 
depressed. Check that all the stoplight 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: Illuminates

Q: Is the check result normal?

YES : Go to Step 18.
NO :  Go to Step 5.

STEP 5. Check for stoplight switch installation
Refer to GROUP 35A − On-vehicle Service 

P.35A-12

.

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Install the stoplight switch correctly. (Refer to GROUP 

35A − On-vehicle Service 

P.35A-12

.) Then, go to Step 

23.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-150

STEP 6. Stoplight switch continuity check
(1) Remove the stoplight switch. (Refer to GROUP 35A − Brake 

Pedal 

P.35A-24

.)

(2) Connect the circuit tester (Ω range) to the stoplight switch 

connector terminal Nos. 1 and 2.

(3) When continuity does not exist with the plunger pressed 

from the outer case end face by the dimension shown in the 
figure, and when continuity exists with the plunger released, 
the switch is in good condition.

Q: Is the check result normal?

YES : Go to Step 7.
NO :  Replace the stoplight switch. (Refer to GROUP 35A − 

Brake Pedal 

P.35A-24

.) Then go to Step 23.

STEP 7. ETACS-ECU fuse No.2 check
Q: Is the check result normal?

YES : Go to Step 12.
NO :  Go to Step 8.

STEP 8. Connector check: C-43 joint connector, C-47 
intermediate connector, C-48 stoplight switch connector, 
C-304 ETACS-ECU connector, C-309 ETACS-ECU 
connector, C-312 ETACS-ECU connector, D-11 
intermediate connector, D-17 intermediate connector, F-05 
high-mounted stoplight, F-06 rear combination light 
(stoplight: RH), F-25 rear combination light (stoplight: LH), 
F-27 intermediate connector
Q: Is the check result normal?

YES : Go to Step 9.
NO :  Repair the defective connector. Then, replace fuse 

No. 2. Then go to Step 23.

AC901847AB

No continuity

Continuity

4.0 ± 0.5 mm 
(0.16 ± 0.02 in)

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-151

STEP 9. Resistance measurement at C-48 stoplight switch 
connector
(1) Disconnect C-48 stoplight switch connector, and measure 

at the wiring harness side.

(2) Disconnect C-312 ETACS-ECU connector and C-43 joint 

connector.

(3) Measure the resistance between the terminal No.1 and the 

body ground.

OK: No continuity

Q: Is the check result normal?

YES : Go to Step 10.
NO :  A short circuit may be present in the wiring harness 

between C-43 joint connector terminal No.2 and C-48 
stoplight switch connector terminal No.1 or between 
C-312 ETACS-ECU connector terminal No.16 and 
C-48 stoplight switch connector terminal No.1. Repair 
the wiring harness if necessary, and then replace fuse 
No.2. Then go to Step 23.

STEP 10. Resistance measurement at C-48 stoplight 
switch connector
(1) Disconnect C-48 stoplight switch connector, and measure 

at the wiring harness side.

(2) Disconnect C-304 ETACS-ECU connector.
(3) Measure the resistance between the terminal No.2 and the 

body ground.

OK: No continuity

Q: Is the check result normal?

YES : Go to Step 11.
NO :  A short circuit may be present in the wiring harness 

between C-304 ETACS-ECU connector terminal No.1 
and C-48 stoplight switch connector terminal No.2. 
Repair the wiring harness if necessary, and then 
replace fuse No.2. Then go to Step 23.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-152

STEP 11. Resistance measurement at C-43 joint connector
(1) Disconnect C-43 joint connector, and measure at the wiring 

harness side.

(2) Disconnect F-06 rear combination light (stoplight: RH) 

connector, F-25 rear combination light (stoplight: LH) 
connector, F-05 highmounted stoplight connector.

(3) Measure the resistance between the terminal No.2 and the 

body ground.

OK: No continuity

Q: Is the check result normal?

YES : Replace fuse No.2. Then go to Step 23.
NO :  A short circuit may be present in the wiring harness 

between C-43 joint connector terminal No.2 and F-06 
rear combination light (stoplight: RH) connector 
terminal No.4 or between C-43 joint connector 
terminal No.2 and F-25 rear combination light 
(stoplight: LH) connector terminal No.4 or between 
C-43 joint connector terminal No.2 and F-05 
highmounted stoplight connector terminal No.1. 
Repair the wiring harness if necessary, and then 
replace fuse No.2. Then go to Step 23 .

STEP 12. Connector check: C-304 ETACS-ECU connector
Q: Is the check result normal?

YES : Go to Step 13.
NO :  Repair the damaged connector.

STEP 13. Measure the voltage at the C-304 ETACS-ECU 
connector.

CAUTION

Measure while the brake pedal is not depressed.
Measure the voltage between terminal No. 1 and the body 
ground by backprobing.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 14.
NO :  Replace the ETACS-ECU (Refer to GROUP 54A − 

ETACS-ECU 

P.54A-742

). Then go to Step 23.

STEP 14. Connector check: C-24 Stoplight switch 
connector
Q: Is the check result normal?

YES : Go to Step 15.
NO :  Repair the damaged connector.