Mitsubishi Lancer Evolution IX. Manual - part 646

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-97

COMMENTS ON TROUBLE SYMPTOM

If communication is not possible with the SRS only, 
the cause is probably an open circuit in the on-board 
diagnostic 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

• Incorrect M.U.T.-II ROM pack

DIAGNOSIS PROCEDURE

STEP 1. Check that the M.U.T.-II/III can 
communicate with the other systems.

Q: Can the M.U.T.-II/III communicate with the other 

systems?
YES : 

Go to Step 2.

NO : 

Refer to GROUP 13A 

− Troubleshooting 

P.13A-237

.

STEP 2. Resistance measurement between 
SRS-ECU connector C-12 (terminal No.20) and 
diagnosis connector C-14 (terminal No.7) 

(1) Disconnect SRS-ECU connector C-12 and 

diagnosis connector C-14, and measure at the 
wiring harness side. 

AC101950AJ

SRS-ECU

Harness side 
connector 
(rear view)
 

C-12 (Y)

Connector: C-12

AC303800

Connector: C-14
<LHD>

AJ

Front side

C-14 (B)

AC303812

Connector: C-14
<RHD>

AE

Front side

C-14(B)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-98

CAUTION

Do not insert a test probe into the terminal from 
of the SRS-ECU connector C-12 its front side 
directly as the connector contact pressure may 
be weakened.
(2) Resistance measurement between the following 

terminals. 

• SRS-ECU connector C-12 (terminal No.20) 

and diagnosis connector C-14 (terminal No.7)

OK: Less than 2 

Ω

Q: Is the check results normal?

YES : 

Go to Step 3.

NO : 

Go to Step 5.

STEP 3. Resistance measurement the earth 
circuit to the SRS-ECU connector C-12

(1) Disconnect SRS-ECU connector C-12 and 

measure at the wiring harness side.

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(2) Check for continuity between terminal 7 and body 

earth.

OK: Less than 2 

Ω

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Check the harness wire for open circuit 
between SRS-ECU connector C-12 
(terminal No.7) and earth, and repair if 
necessary.

131415 1617 1819 20

5 6 7 8 9 10 1112

1 2

3 4

1 2 3 4 5 6 7 8
9 10 11121314 15 16

AC201667AN

C-12 Harness side 
connector 
(rear view) 

C-14 Diagnosis 
connector 

AC101950AJ

SRS-ECU

Harness side 
connector 
(rear view)
 

C-12 (Y)

Connector: C-12

AC006264

13 14 15 16 17 18 19 20

5 6 7 8 9 10 11 12

1 2

3 4

AM

C-12 Harness side 
connector (rear view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-99

STEP 4. Voltage measurement the power supply 
circuit to the SRS-ECU connector C-12

(1) Disconnect SRS-ECU connector C-12 and 

measure at the wiring harness side.

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

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(4) Voltage measurement between terminals 13, 16 

and body earth.

OK: 9 V or more

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 6.

STEP 5. Check the harness wires between 
SRS-ECU connector C-12 and diagnosis 
connector C-14.

AC101950AJ

SRS-ECU

Harness side 
connector 
(rear view)
 

C-12 (Y)

Connector: C-12

AC006265

13 14 15 16 17 18 19 20

5 6 7 8 9 10 11 12

1 2

3 4

AR

C-12 Harness side 
connector (rear view)

AC101950AJ

SRS-ECU

Harness side 
connector 
(rear view)
 

C-12 (Y)

Connector: C-12

AC303800

Connector: C-14
<LHD>

AJ

Front side

C-14 (B)

AC303812

Connector: C-14
<RHD>

AE

Front side

C-14(B)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-100

NOTE: 

Prior to the wiring harness inspection, check junction 
block connector C-101 <LHD> or C-23 <RHD>, and 
repair if necessary.

Q: Is the check result normal?

YES : 

An intermittent malfunction is suspected 

(Refer to GROUP 00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

NO : 

Repair the harness wires.

STEP 6. Check the harness wires between 
SRS-ECU connector C-12 and ignition switch 
connector C-208.

AC303798

Connector: C-101
<LHD>

BA

2

1

3

13

12

14

21

10

5

4

6

16

15

17

7 8 9

19

18

20

11

22

C-101 (L)

AC303814

Connector: C-23
<RHD>

AW

C-23 (B)

AC101950AJ

SRS-ECU

Harness side 
connector 
(rear view)
 

C-12 (Y)

Connector: C-12

AC303806

Connector: C-208
<LHD>

Harness side 
connector 
(front view)

AI

Clock spring

AC303820 AE

Connector: C-208
<RHD>

Harness side 
connector 
(front view)

Clock spring