Mitsubishi Evolution X. Manual - part 663

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-99

(5) Check for continuity between C-37 harness side connector 

terminals 1, 2 and body ground.
It should be an open circuit.

Q: Is it open circuit?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1B10 sets, 
replace the SRS-ECU (Refer to 

P.52B-383

). Then go 

to Step 6.

NO :  Go to Step 5.

STEP 5. Check harness wires for short circuit to ground 
between SRS-ECU connector C-37 (terminal No.1 and 2) 
and knee air bag module connector C-39 (terminal No.2 
and 1).
Q: Are the harness wires between SRS-ECU connector 

C-37 (terminal No.1 and 2) and knee air bag module 
connector C-39 (terminal No.2 and 1) in good condition?
YES : Go to Step 6.
NO :  Replace the harness wires between SRS-ECU 

connector C-37 and knee air bag module connector 
C-39. Then go to Step 6.

STEP 6. Recheck for diagnostic trouble code. 
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC B1B10 set?

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

AC608812

C-37 Harness side 
connector (front view)

FJ

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-100

DTC B1B11: Driver's Knee Air Bag (Squib) System (Shorted To Squib Circuit Power Supply)

CAUTION

If DTC B1B11 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

The SRS-ECU judges how severe a collision is by 
detecting signals from the front impact sensors and 
the front air bag analog G-sensor. If the impact is 
over a predetermined level, the SRS-ECU sends an 
ignition signal. At this time, if the front air bag safing 
G-sensor is on, the knee air bag module will deploy. 

.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance 
between the input terminals of the knee air bag mod-
ule (squib).

.

TROUBLESHOOTING HITS

• Damaged wiring harnesses or connectors

• Short to power supply in the knee air bag module 

(squib) harness

• Malfunction of the SRS-ECU

KNEE AIR BAG
MODULE (SQUIB)

SRS-ECU

CONNECTOR LOCK SWITCH 

CONNECTOR COUPLED: ON 

CONNECTOR UNCOUPLED: OFF

NOTE

:   

 

 

Knee Air Bag Module (Squib) Circuit

AC708951AC

C-37 (Y)

Connector: C-37

AC708950AB

Connector: C-39

C-39 (B)

 

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-101

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)

• MB991865: Dummy resistor

• MB991884: Resister harness

STEP 1. 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 2.
NO :  Repair the CAN bus line (Refer to GROUP 54C, 

Diagnosis 

P.54C-14

).

STEP 2. 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 3.
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

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-102

STEP 3. Check the knee air bag module.
(1) Disconnect the negative battery terminal.
(2) Disconnect knee air bag module connector C-39. Use a 

flat-tipped screwdriver to unlock the locking button at the 
harness side connector by withdrawing it toward you in two 
stages, and then disconnect the connector.

(3) Connect special tool MB991865 to special tool MB991884.
(4) Connect special tool MB991884 to the C-39 harness side 

connector.

(5) Connect the negative battery terminal.
(6) Erase diagnostic trouble code memory, and check the 

diagnostic trouble code.

Q: Is DTC B1B11 set?

YES : Go to Step 4.
NO :  Replace the driver’s knee air bag module (Refer to 

P.52B-398

). Then go to Step 6.

AC609126AC

Locking button

Flat-tipped
screwdriver

Pre-tensioner

Harness side
connector

AC301553CA

C-39 Harness side 
connector

MB991884 

(Resistor harness)

MB991865

(Dummy resistor: 3    )