Mitsubishi Evolution X. Manual - part 702

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-255

DTC B210D: Battery Abnormal Low Voltage

ETACS-ECU

FUSIBLE
LINK

34

IGNITION
SWITCH (IG1)

IG1
RELAY

SRS-ECU

POWER 
SUPPLY

IG1 Power Supply Circuit

JOINT CONNECTOR (4)

JOINT CONNECTOR (5)

AC708951AD

Connector: C-36

C-36 (Y)

AC708972BD

Connectors: C-309, C-313

Junction block

C-309 (B)

C-313 (BR)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-256

CAUTION

If the diagnostic trouble code B210D is set in the 
SRS-ECU, always diagnose the CAN main bus 
line.

.

CIRCUIT 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.

.

DTC SET CONDITIONS

The code is set when the battery voltage becomes 
low or when the open circuit occurs to the power sup-
ply circuit.

.

TROUBLESHOOTING HINTS

• Battery voltage drop

• Open circuit to power supply circuit

• Damaged wiring harnesses or connectors

• Malfunction of the SRS-ECU

• Malfunction of ETACS-ECU

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 (Vehicles with 

CAN communication system)

STEP 1. Power supply fuse check.
Q: Is the fuse in good condition?

YES : Go to Step 3.
NO :  Go to Step 2.

STEP 2. Wiring harness check between the fusible link (34) 
and the C-36 SRS-ECU connector terminal No. 61/62.

•  Short circuit check for SRS-ECU power supply wire

Q: Is the check result normal?

YES : Replace the power supply fuse.
NO :  Repair the wiring harness. And than replace the 

power supply fuse.

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

P.54A-9

.

Q: Is the check result normal?

YES : Go to Step 4.
NO :  Charge or replace the battery.

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-257

STEP 4. Measure the voltage at the ETACS-ECU connector.
(1) Disconnect the C-309 ETACS-ECU connector.
(2) Measure the voltage between the C-309 harness side 

connector terminal No. 1 and the body ground.

• The voltage should measure 12 volts (battery positive 

voltage).

Q: Is the measured voltage approximately 12 volts (battery 

positive voltage)?
YES : Go to Step 6.
NO :  Go to Step 5.

STEP 5. Wiring harness check between the fusible link (34) 
and the C-309 ETACS-ECU connector terminal No. 1.

•  Open circuit check for ETACS-ECU power supply wire

Q: Is the check result normal?

YES : Go to Step 10.
NO :  Repair the wiring harness.

STEP 6. Using scan tool MB991958, diagnose the ETACS.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958. Refer to "How to connect the 

scan tool 

P.52B-28

."

(2) Erase the DTC.
(3) Turn the ignition switch to the "ON" position.
(4) Check if the DTC is set.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?

YES : Diagnose the ETACS (Refer to GROUP 54A, ETACS, 

Diagnosis 

P.54A-582

).

NO :  Check the input signal of ETACS-ECU ignition switch 

(IG1) (Refer to GROUP 54A 

− ETACS, Symptom 

procedures 

P.54A-642

). Than go to step 7.

AC709344

C-309 Harness side 
connector (rear view)

AE

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-258

STEP 7. Using scan tool MB991958, diagnose the CAN bus 
line.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958. Refer to "How to connect the 

scan tool 

P.52B-28

."

(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

YES : Go to Step 8.
NO :  Repair the CAN bus line (Refer to GROUP 54C, 

Diagnosis 

P.54C-14

).

STEP 8. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?

YES : Go to Step 9.
NO :  There is an intermittent malfunction such as poor 

engaged connector(s) or open circuit (Refer to 
GROUP 00, How to Cope with Intermittent 
Malfunction 

P.00-15

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB