Mitsubishi Outlander GS45X. Manual - part 430

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-147

DTC C121C: Torque request signal rejection

CAUTION

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

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

− CAN Bus Line Diagnostic Flow 

P.54C-10

).

• Whenever ECU is replaced, ensure that the CAN bus 

lines are normal.

• Do not drop or shock the G and yaw rate sensor.
• When the G and yaw rate sensor is replaced, always 

carry out calibration to make ASC-ECU learn the neu-
tral point (Refer to 

P.35C-282

).

• When the hydraulic unit (integrated with ASC-ECU) is 

replaced, always carry out the calibration of the steer-
ing wheel sensor, the G and yaw rate sensor and brake 
fluid pressure sensor (Refer to 

P.35C-282

, 

P.35C-283

 

and 

P.35C-284

).

.

CIRCUIT OPERATION

ASC-ECU sends the signal to the engine control module as 
necessary to decrease the engine output for the ASC system 
operation.

.

DTC SET CONDITIONS

This diagnostic trouble code is set when the request for the 
decrease of output is rejected by the engine control module.

.

PROBABLE CAUSES

• Wrong coding

• Engine control module malfunction

• ASC-ECU malfunction

• External noise interference

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.
Use scan tool 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 

P.54C-17

). On 

completion, go to Step 2.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-148

STEP 2. DTC recheck after resetting CAN bus lines
Q: Is DTC C121C set?

YES : Go to Step 3.
NO :  The procedure is complete.

STEP 3. M.U.T.-III other system diagnostic trouble code
Use scan tool to check that the diagnostic trouble code is set in 
the engine control module.
Q: Is any DTC set?

YES : Troubleshoot the engine control module diagnostic 

trouble code <Refer to GROUP 13A 

− Diagnostic 

Trouble Code Chart 

P.13A-49

 (2.4L engine) or 

GROUP 13B 

− Diagnostic Trouble Code Chart 

P.13B-50

 (3.0L engine)>.

NO :  Go to Step 4.

STEP 4. M.U.T.-III diagnostic trouble code
Check that the diagnostic trouble code U1417 is set in 
ASC-ECU.
Q: Is DTC U1417 set?

YES : Troubleshoot for the diagnostic trouble code U1417 

(Refer to 

P.35C-212

). Then go to Step 5.

NO :  Replace the hydraulic unit (integrated with ASC-ECU) 

(Refer to 

P.35C-287

). Then go to Step 7.

STEP 5. M.U.T.-III data list
Check the following data list (Refer to 

P.35C-270

).

• Item 68: Allow ESP torque request

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Troubleshoot the engine control module diagnostic 

trouble code <Refer to GROUP 13A 

− Diagnostic 

Trouble Code Chart 

P.13A-49

 (2.4L engine) or 

GROUP 13B 

− Diagnostic Trouble Code Chart 

P.13B-50

 (3.0L engine)>, and then go to Step 7.

STEP 6. Check whether the diagnostic trouble code is 
reset.
Erase the DTC.
Q: Is DTC C121C set?

YES : Replace the hydraulic unit (integrated with ASC-ECU) 

(Refer to 

P.35C-287

). Then go to Step 7.

NO :  If the trouble symptom is resolved, an intermittent 

malfunction such as poorly engaged connector(s) or 
wiring harness is suspected (Refer to GROUP 00 

− 

How to Use Troubleshooting/How to Cope with 
Intermittent Malfunctions 

P.00-15

).

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-149

STEP 7. Check whether the diagnostic trouble code is 
reset.
Erase the DTC.
Q: Is DTC C121C set?

YES : Return to Step 1.
NO :  The procedure is complete.

DTC C1290: CAN time-out error

CAUTION

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

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

− CAN Bus Line Diagnostic Flow 

P.54C-10

).

• If the diagnostic trouble code No.C1290 is set in 

ASC-ECU, always diagnose the CAN bus line. If there is 
any fault in the CAN bus lines, an incorrect diagnostic 
trouble code may be set. In this case, the set diagnostic 
trouble code is not highly reliable.

• Whenever ECU is replaced, ensure that the CAN bus 

lines are normal.

• When the hydraulic unit (integrated with ASC-ECU) is 

replaced, always carry out the calibration of the steer-
ing wheel sensor, the G and yaw rate sensor and brake 
fluid pressure sensor (Refer to 

P.35C-282

, 

P.35C-283

 

and 

P.35C-284

).

• When the diagnostic trouble code No.C1290 is set in 

ASC-ECU, the diagnostic trouble code for another sys-
tem may also be set. When the diagnostic trouble code 
for another system is set, carry out diagnosis for that 
system first.

.

CIRCUIT OPERATION

ASC-ECU receives signals necessary for the operations of 
ABS or ASC from the engine control module, TCM, AWD-ECU, 
ETACS-ECU, and the steering wheel sensor via the CAN bus 
lines.

.

DTC SET CONDITIONS

ASC-ECU receives signals necessary for the operations of 
ABS or ASC from the engine control module, TCM, AWD-ECU 
or AWC-ECU, ETACS-ECU, and steering wheel sensor via 
CAN bus lines. This diagnostic trouble code is stored when 
ASC-ECU cannot receive the signals necessary for the opera-
tions of ABS or ASC from the engine control module, TCM, 
AWD-ECU or AWC-ECU, ETACS-ECU, and steering wheel 
sensor.

.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-150

PROBABLE CAUSES

• Engine control module malfunction

• TCM malfunction

• AWD-ECU or AWC-ECU malfunction

• Steering wheel sensor malfunction

• CAN bus malfunction

• ASC-ECU malfunction

• ETACS-ECU malfunction

• ETACS-ECUs have been interchanged between two vehi-

cles.

• Connector disconnected or improperly connected

• Stretched or broken wires

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.
Use scan tool 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 

− 

CAN Bus Diagnostics Table 

P.54C-17

). On 

completion, go to Step 4.

STEP 2. Using scan tool MB991958, diagnostic trouble 
code
Check that the diagnostic trouble codes U0100, U0101, U0114, 
U0126, and U0141 are set in ASC-ECU.
Q: Is any DTC set?

YES : Troubleshoot for the relevant diagnostic trouble code 

(Refer to 

P.35C-18

).

NO :  Go to Step 3.

STEP 3. Using scan tool MB991958,  other system 
diagnostic trouble code
Using scan tool, check if the diagnostic trouble codes are set 
from the engine control module, TCM, AWD-ECU or AWC-ECU 
and ETACS-ECU or not.
Q: Is any DTC set?

YES : Troubleshoot the relevant diagnostic trouble code, 

and then go to Step 4.

NO :  Go to Step 4.