Mitsubishi L200. Manual — part 453

TROUBLESHOOTING

ACTIVE STABILITY & TRACTION CONTROL SYSTEM (ASTC)

35C-68

DIAGNOSIS CODE SET CONDITIONS
These diagnosis code will be set under the cases
below.

Code No. C1278

• When the solenoid valve relay monitor judges

that the solenoid valve relay is turned "ON"
although it actually is turned "OFF"

Code No. C1279

• When the solenoid valve relay monitor judges

that the solenoid valve relay is turned "OFF"
although it actually is turned "ON"

PROBABLE CAUSES
The most likely causes for these diagnosis codes to
set are:

• Fusible link malfunction

• Damaged wiring harness or connector

• Malfunction of the hydraulic unit assembly (inte-

grated with ASTC-ECU)

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis.
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.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Check if the diagnosis code is set.
(6) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Are the diagnosis codes No.C1278 or C1279 set?

YES :

Go to Step 3.

NO :

The procedure is complete.

STEP 3. Connector check: A-48 ASTC-ECU
connector

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Repair or replace the damaged
component(s). Then go to Step 9.

STEP 4. Fusible link check: Check the fusible link
No.21

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Go to Step 5.

STEP 5. Resistance measurement at A-48 ASTC-
ECU connector
(1) Remove the fusible link No.21.
(2) Disconnect the A-48 ASTC-ECU connector.
(3) Measure the resistance between the A-48 ASTC-

ECU connector terminal No.1 and body earth.

OK: No continuity

Q: Is the check result normal?

YES :

Replace the fusible link No.21. Then go to

Step 9.

NO :

Repair the wiring harness between the
fusible link No.21 and the A-48 ASTC-ECU
connector terminal No.1. Then replace the
fusible link No.21. Then go to Step 9.

STEP 6. Voltage measurement at A-48 ASTC-ECU
connector
(1) Disconnect the A-48 ASTC-ECU connector.
(2) Measure the voltage between the A-48 ASTC-

ECU connector terminal No.1 and the body earth.

OK: Battery voltage

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

The open circuit may be present in the
solenoid valve power supply circuit. Repair
the wiring harness between the fusible link
No.21 and the A-48 ASTC-ECU connector
terminal No.1. Then go to Step 9.

STEP 7. Resistance measurement at A-48 ASTC-
ECU connector
(1) Disconnect the A-48 ASTC-ECU connector.
(2) Measure the resistance between the A-48 ASTC-

ECU connector terminal No.12 and the body
earth, and between the terminal No.24 and body
earth.

OK: Continuity exists (2

Ω or less)

Q: Is the check result normal?

YES :

Go to Step 8.

NO :

The open circuit may be present in the earth
circuit. Repair the wiring harness between
the A-48 ASTC-ECU connector terminal
No.12 and the body earth, and between the
A-48 ASTC-ECU connector terminal No.24
and the body earth. Then go to Step 9.

TROUBLESHOOTING

ACTIVE STABILITY & TRACTION CONTROL SYSTEM (ASTC)

35C-69

STEP 8. Check whether the diagnosis code is
reset.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Check that the ABS warning lamp, Brake warning

lamp, ASTC indicator lamp and ASTC OFF
indicator lamp goes out.

(6) Check if the diagnosis code is set.
(7) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Are the diagnosis code No.C1278 or C1279 set?

YES :

Replace the hydraulic unit assembly

(integrated with ASTC-ECU) (Refer to

P.35C-140

.). Then go to Step 9.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Cope with Intermittent

Malfunctions .).

STEP 9. Check whether the diagnosis code is
reset.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Check that the ABS warning lamp, Brake warning

lamp, ASTC indicator lamp and ASTC OFF
indicator lamp goes out.

(6) Check if the diagnosis code is set.
(7) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Are the diagnosis code No.C1278 or C1279 set?

YES :

Go to Step 1.

NO :

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY & TRACTION CONTROL SYSTEM (ASTC)

35C-70

Code No.C1291: Reverse signal (seizure)

IGNITION
SWITCH (IG1)

BACK-UP
LAMP SWITCH

ASTC-
ECU

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

Reverse signal Circuit

ACB00774

AC800980

AG

Connector: A-48

(B)

AC900690 AB

(B)

Connector: B-02

Harness side

2 1

TROUBLESHOOTING

ACTIVE STABILITY & TRACTION CONTROL SYSTEM (ASTC)

35C-71

CAUTION

If there is any problem in the CAN bus lines, an
incorrect diagnosis code may be set. Diagnose
the CAN bus lines before the diagnosis codes
(Refer to GROUP 54C

− CAN Bus Diagnostics

Table .).
OPERATION
ASTC-ECU monitors if the lever is shifted to the
reverse position.

DIAGNOSIS CODE SET CONDITION
This code is set when the power supply and wheel
speed sensor are normal and ASTC-ECU receives
the signal that the shift lever is at the reverse position
while the vehicle drives at 50 km/h or more.

PROBABLE CAUSES
The most likely causes for this diagnosis code to set
is:

• Damaged wiring harness or connector

• Malfunction of the back-up lamp switch

• Malfunction of the hydraulic unit assembly (inte-

grated with ASTC-ECU)

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis.
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 Diagnosis Table .). On

completion, go to Step 2.

STEP 2. Check whether the diagnosis code is
reset.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Check if the diagnosis code is set.
(6) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Is code No.C1291 set?

YES :

Go to Step 3.

NO :

The procedure is complete.

STEP 3. Check ASTC-ECU connector A-48 and
back-lamp switch connector B-02 for loose,
corroded or damaged terminals, or terminals
pushed back in the connector.

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Check the back-lamp switch (Refer to
GROUP 22C, Transmission Inspection .).
Then go to Step 6.

STEP 4. Check the harness wires between ASTC-
ECU connector A-48 terminal No.32 and back-
lamp switch connector B-02 terminal 1.
Check the short to power supply between each har-
ness connector.

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Repair the wiring harness. Then go to Step
6.

STEP 5. Check whether the diagnosis code is
reset.
Check again if the diagnosis code is set.
(1) Turn the ignition switch to the "ON" position.
(2) Erase the diagnosis code.
(3) Turn the ignition switch to the "LOCK" (OFF)

position.

(4) Turn the ignition switch to the "ON" position.
(5) Check if the diagnosis code is set.
(6) Turn the ignition switch to the "LOCK" (OFF)

position.

Q: Is code No.C1291 set?