Mitsubishi L200. Manual - part 646

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-255

SYMPTOM PROCEDURES <VEHICLES 
WITH SIDE-AIRBAG AND CURTAIN 
AIR BAG>

 Inspection Procedure 1: Communication with M.U.T.-III is not possible (Communication is not 
possible with SRS).

FRONT SIDE

AC801154

IGNITION
SWITCH (IG1)

SRS-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

DIAGNOSIS
CONNECTOR

SRS-ECU Power Supply Circuit

AC

OPERATION

• The SRS-ECU is powered from the ignition 

switch (IG1).

• The SRS-ECU power is supplied from two cir-

cuits. Even if one circuit is shut off, the air bag 
can inflate.

• The SRS system diagnosis can be done by con-

necting M.U.T.-III to the diagnosis connector.

COMMENTS ON TROUBLE SYMPTOM
If communication is not possible with the SRS only, 
the cause is probably an open circuit in the diagnosis 
output circuit of the SRS or in the power circuit 
(including earth circuit).

PROBABLE CAUSES

• Damaged wiring harnesses or connectors

• Malfunction of the SRS-ECU

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-256

DIAGNOSIS PROCEDURE

STEP 1. Wiring harnesses check between SRS-
ECU connector C-154 (terminal No.38) and 
diagnosis connector C-22 (terminal No.7).

AC903856BO

Connector: C-22 <LHD>

C-22 (B)

Harness side 
(Front side)

AC903868

CH

Connector: C-22 <RHD>

C-22 (B)

Harness side 
(Front side)

AC801404

AJ

Connector: C-154

C-154 (Y)

Harness side 
connector 
(rear view)

• Check the wiring harness for open circuit.

Q: Is the check results normal?

YES : 

Go to Step 2.

NO : 

Repair the wiring harness.

STEP 2. Resistance measurement the earth 
circuit to the SRS-ECU connector C-154
(1) Disconnect the negative battery terminal.

AC801404

AJ

Connector: C-154

C-154 (Y)

Harness side 
connector 
(rear view)

(2) Disconnect SRS-ECU connector C-154 and 

measure at the wiring harness side.

AC800962 CG

C-154 Harness side 
connector (rear view)

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(3) Check for continuity between terminal 41 and 

body earth.

OK: Continuity (Less than 2 

Ω)

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Check the harness wire for open circuit 
between SRS-ECU connector C-154 
(terminal No.41) and earth, and repair if 
necessary.

POST-COLLISION DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-257

STEP 3. Voltage measurement the power supply 
circuit to the SRS-ECU connector C-154.
(1) Disconnect the negative battery terminal.

AC801404

AJ

Connector: C-154

C-154 (Y)

Harness side 
connector 
(rear view)

(2) Disconnect SRS-ECU connector C-154 and 

measure at the wiring harness side.

(3) Connect the negative battery terminal.
(4) Turn the ignition switch to the "ON" position.

AC800963 AY

C-154 Harness side 
connector (rear view)

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(5) Voltage measurement between terminals 37, 43 

and body earth.

OK: 9 V or more

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Check the harness wires for open or short 
circuit between SRS-ECU connector C-158 
(terminal No.37, 43) and ignition switch, and 
repair if necessary. 

STEP 4. Retest the system.

Q: Does the M.U.T.-III communicate normally with the 

SRS system?
YES : 

An intermittent malfunction is suspected 

(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction ).

NO : 

Replace the SRS-ECU (Refer to 

P.52B-

266

).

POST-COLLISION DIAGNOSIS

M1524001102353

Whether or not the air bags have deployed, check 
and service the vehicle after collision as follows:

POST-COLLISION DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-258

SRS-ECU MEMORY CHECK

AC509179

AB

Diagnosis

connector

MB991827

MB991824 

MB991910

<LH drive vehicles>

CAUTION

Refer to that the ignition switch is "LOCK" (OFF) 
when connecting or disconnecting M.U.T.-III.
1. Connect the M.U.T.-III to the diagnosis connector 

(Refer to GROUP 00, Diagnosis Function).

2. Read (and write down) all displayed diagnosis 

codes (Refer to 

P.52B-12

).

NOTE: If battery power supply has been shut 
down by the collision, the M.U.T.-III cannot com-
municate with the SRS-ECU. Check and, repair if 
necessary, the instrument panel wiring harness 
before the next job.

3. Use the M.U.T.-III to read the data list (how long 

trouble(s) have continued and how often memory 
have been erased).

Data list

No.

Data list Item

Applicability

01

Failure continuation time 1

Maximum time to be stored: 9,999 minutes 
(approximately 7 days)

02

Failure continuation time 2

03

Elimination times

Maximum time to be stored: 250 times

4. Erase the diagnosis codes and after waiting 5 

seconds or more read (and write down) all 
displayed diagnosis codes.

REPAIR PROCEDURE

WHEN FRONT AIR BAGS DEPLOY IN A COLLI-
SION.
1. Replace the following parts with new ones.

• Front impact sensor (Refer to 

P.52B-263

).

• SRS-ECU (Refer to 

P.52B-266

).

• Driver’s air bag modules (Refer to 

P.52B-268

).

• Passenger’s (front) air bag modules (Refer to 

P.52B-268

).

• Seat belt with pre-tensioner (Refer to 

P.52B-284

).

2. Check the following parts and replace if there are 

any malfunctions.

• Clock spring (Refer to 

P.52B-268

).

• Steering wheel, steering column and shaft 

assembly

(1) Check the wiring harness (built into the 

steering wheel) and connectors for damage, 
and terminals for deformation.

(2) Install the air bag module to check fit or 

alignment with the steering wheel.

(3) Check the steering wheel for noise, binds or 

difficult operation and excessive free play.

(4) Check the steering column shaft shock 

absorbing mechanism (Refer to GROUP 37, 
On-vehicle Service ).

• Instrument panel (Refer to GROUP 52A, Instru-

ment panel assembly ).

• Passenger’s air bag cut off switch (Refer to 

P.52B-287

).