Mitsubishi Colt Ralliart. Manual - part 557

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-66

CAUTION

Insert an insulator such as a cable tie to a depth 
of 4 mm or more, otherwise the short spring will 
not be released.
(4) Insert a cable tie [3 mm wide, 0.5 mm thick] 

between terminals 5, 6 and the short spring to 
release the short spring.

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(5) Resistance measurement between B-35 harness 

side connector terminals 5 and 6.

OK: Open circuit.

Q: Is the check result normal?

YES : . 

Go to Step 6.

NO : . 

Repair the harness wires between 

SRS-ECU connector B-35 (terminal No.5 
and 6) and passenger’s (front) seat belt 
pre-tensioner connector C-20 (terminal No.1 
and 2).

STEP 6. Check whether the diagnosis code is 
reset. 

Q: Is diagnosis code 28 set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-143

).

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-13

).

AC208510

Section
A - A

B-35 
Harness side connector
(front view)

Cable tie

Short spring

Terminal

AE

4 mm or more

A

A

13 14

16 17

19 20

5 6 7 8 9 10 11 12

1 2

3 4

18

15

AC208507

B-35Harness side connector 
(rear view)

AE

Main

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TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-67

Code No.29: Passenger's (front) seat belt pre-tensioner (squib) system (open-circuited in the squib 
circuit)

OPERATION

The SRS-ECU judges how severe a collision is by 
detecting signals from the front impact sensors and 
the front air bag analogue 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 pre-tensioner will deploy. 

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if the passenger's (front) 
seat belt pre-tensioner squib wire(s) are 
open-circuited. However, if no diagnosis code resets, 
the SRS warning lamp will be switched off (diagnosis 
code will be retained).

PROBABLE CAUSES

• Open circuit in the passenger's (front) seat belt 

pre-tensioner (squib) circuit

• Improper connector contact

• Malfunction of the SRS-ECU

AC510233

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

SEAT BELT
PRETENSIONER
(LH)

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

NOTE

: CONNECTOR COUPLED: ON 
  CONNECTOR UNCOUPLED: OFF

Passenger's (Front) Seat Belt Pre-tensioner (Squib) 

AB

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-68

DIAGNOSIS PROCEDURE

STEP 1. Check the diagnosis code by connecting 
a dummy resistor. (M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect passenger's (front) seat belt 

pre-tensioner connector C-20. Use a flat-tipped 
screwdriver to pull out the locking button at the 
harness side connector, and then disconnect the 
connector.

(3) Connect special tool dummy resistor (MB991865) 

to special tool resistor harness (MB991884).

(4) Connect special tool (MB991884) to the C-20 

harness side connector.

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

the diagnosis code.

Q: Is diagnosis code 29 set?

YES : . 

Go to Step 2.

NO : . 

Replace the passenger's (front) seat belt 

with pre-tensioner (Refer to 

P.52B-159

). 

STEP 2. Resistance measurement between 
SRS-ECU connector B-35 (terminal No.5 and 6) 
and the passenger's (front) seat belt 
pre-tensioner connector C-20 (terminal No.1 and 
2)
(1) Disconnect the negative battery terminal.

(2) Disconnect SRS-ECU connector B-35 and 

passenger's (front) seat belt pre-tensioner 
connector C-20. For connector C-20, use a 
flat-tipped screwdriver to pull out the locking 
button at the harness side connector, and then 
disconnect the connector.

AC207223 AE

Harness side 
connector 
(front view)
 

Connector: C-20

C-20 (B)

Centre

pillar

AC208430AE

Pre-tensioner

connector

Locking 

button

Harness side 

 connector

Flat-tipped 

screwdriver

MB991865
(Dummy resistor : 3 

Ω)

C-20 Harness side 
connectors

MB991884
(Resistor
harness)

AG

AC206285

AF

B-35 (Y)

Connector: B-35

Harness side 
connector 
(rear view)
 

AC207223 AE

Harness side 
connector 
(front view)
 

Connector: C-20

C-20 (B)

Centre

pillar

AC208430AE

Pre-tensioner

connector

Locking 

button

Harness side 

 connector

Flat-tipped 

screwdriver

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-69

(3) Connect C-20 harness side connector to special 

tool resistor harness (MB991884).

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.

(4) Resistance measurement between the following 

terminals. 

• SRS-ECU connector B-35 terminal No.5 and 

the special tool terminal No.2

• SRS-ECU connector B-35 terminal No.6 and 

the special tool terminal No.1

OK: Continuity (Less than 2 

Ω)

Q: Are the check results normal?

YES : . 

Go to Step 3.

NO : . 

Repair the harness wires between 

SRS-ECU connector B-35 (terminal No.5 
and 6) passenger’s (front) seat belt 
pre-tensioner connector C-20 (terminal No.1 
and 2).

STEP 3.Check whether the diagnosis code is 
reset.

Q: Is diagnosis code 29 set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-143

).

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-13

).

AC201287BQ

C-20 

Harness side
connector

MB991884

13 14

16 17

19 20

5 6 7 8 9 10 11 12

1 2

3 4

18

15

2

1

AC208506AD

Resister harness 
connector

B-35 
Harness side 
connector (rear view)

Main

Index

Group

TOC