Mazda 6. Manual - part 363

ON-BOARD DIAGNOSTIC [AIR BAG SYSTEM] 

T–199

T

Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT METER IG 15 A FUSE

• Turn ignition switch to LOCK position.

• Disconnect negative battery cable.

• Remove METER IG 15 A fuse.

• Is fuse okay?

Yes

Reinstall METER IG 15 A fuse, then go to next step.

No

Replace METER IG 15 A fuse.

2

INSPECT FOR CONTINUITY BETWEEN 
METER IG 15 A FUSE AND INSTRUMENT 
CLUSTER

• Connect negative battery cable.

• Turn ignition switch to ON position.

• Measure voltage at instrument cluster 

connector terminal 2V.

• Is voltage more than 9 V?

Yes

Go to next step.

No

Repair wiring harness.

3

INSPECT WIRING HARNESS BETWEEN 
INSTRUMENT CLUSTER AND SAS UNIT

Warning
• Handling air bag system components 

improperly can accidentally deploy air 
bag modules and pre-tensioner seat 
belts, which may seriously injure you. 
Read AIR BAG SYSTEM SERVICE 
WARNINGS before handling air bag 
system components.
(See 

T–117 SERVICE WARNINGS

)

• Turn ignition switch to LOCK position.

• Disconnect negative battery cable and wait 

for more than 1 minute.

• Remove column cover.

• Disconnect clock spring connector.

• Remove glove compartment.

• Disconnect passenger-side air bag module 

connector.

• Disconnect driver and passenger-side 

curtain air bag module connectors. (Vehicles 
with curtain air bag)

• Disconnect driver and passenger-side side 

air bag module connectors. (Vehicles with 
side air bag)

• Remove B-pillar lower trims. (Vehicle with 

pre-tensioner seat belt)

• Disconnect driver and passenger-side pre-

tensioner seat belt connectors. (Vehicle with 
pre-tensioner seat belt)

• Turn up floor covering.

• Disconnect all SAS unit connectors.

• Disconnect instrument cluster.

• Inspect following wiring harness between 

SAS unit and instrument cluster terminals for 
short to ground, short to power supply, and 
open circuit:
— 1T—1O

• Is wiring harness okay?

Yes

Go to next step.

No

Replace wiring harness.

4

INSPECT AIR BAG SYSTEM WARNING 
LIGHT

• Connect instrument cluster.

• Turn ignition switch to ON position.

• Is air bag system warning light illuminated?

Yes

Go to next step.

No

Replace instrument cluster.
(See 

T–72 INSTRUMENT CLUSTER REMOVAL/

INSTALLATION

)

5

INSPECT AIR BAG SYSTEM WARNING 
LIGHT

• Using a jumper wire, cause a short circuit 

between instrument cluster terminal 1O and 
ground.

• Does air bag system warning light go out?

Yes

[Present malfunction diagnosis]
Replace SAS unit.
(See 

T–124 SAS UNIT REMOVAL/INSTALLATION

)

[Past malfunction diagnosis]
Troubleshooting completed.

No

Replace instrument cluster.
(See 

T–72 INSTRUMENT CLUSTER REMOVAL/

INSTALLATION

)

T–200

ON-BOARD DIAGNOSTIC [AIR BAG SYSTEM] 

End Of Sie

DTC B1871

A6E817401046W08

Diagnostic procedure

DTC B1871

Occupancy sensor system (communication error, sensor internal circuit abnomal)

DETECTION 

CONDITION

Warning
• Detection conditions are for understanding DTC outline before performing inspection. 

Performing inspection with only detection conditions may cause injury due to operating error 
or damage the system. When performing inspection, always follow inspection procedure.

• Malfunction in wiring harness between SAS unit and occupancy sensor

• Malfunction in occupancy sensor circuit

POSSIBLE 

CAUSE

• Open or short circuit in wiring harness between METER IG 15 A fuse and occupancy sensor

• Open or short circuit in wiring harness between SAS unit and occupancy sensor

• Open circuit in wiring harness between occupancy sensor and ground

• Occupancy sensor malfunction

• SAS unit malfunction

STEP

INSPECTION

ACTION

1

• Is vehicle equipped with passenger-side air bag 

cut-off function?

Yes

Go to next step.

No

[Present malfunction diagnosis]
Replace SAS unit.
(See 

T–124 SAS UNIT REMOVAL/INSTALLATION

)

[Past malfunction diagnosis]
Troubleshooting completed.

ON-BOARD DIAGNOSTIC [AIR BAG SYSTEM] 

T–201

T

End Of Sie

2

INSPECT WIRING HARNESS BETWEEN 
OCCUPANCY SENSOR AND SAS UNIT

Warning
• Handling air bag system components 

improperly can accidentally deploy air bag 
modules, and pre-tensioner seat belts 
which may seriously injure you. Read AIR 
BAG SYSTEM SERVICE WARNINGS 
before handling air bag system 
components.
(See 

T–117 SERVICE WARNINGS

)

• Turn ignition switch to LOCK position.

• Disconnect negative battery cable and wait for 

more than 1 minute.

• Remove column cover.

• Disconnect clock spring connector.

• Remove glove compartment.

• Disconnect passenger-side air bag module

connector.

• Disconnect driver and passenger-side side air 

bag module connectors. (Vehicle with side air 
bag)

• Disconnect driver and passenger-side curtain air 

bag module connectors. (Vehicles with curtain 
air bag)

• Remove B-pillar lower trim. (Vehicle with pre-

tensioner seat belt)

• Disconnect drive- and passenger-side pre-

tensioner seat belt connectors. (Vehicle with 
pre-tensioner seat belt)

• Turn up floor covering.

• Disconnect all SAS unit connectors.

• Disconnect occupancy sensor connector.

• Connect negative battery cable.

• Inspect following wiring harness between SAS 

unit and occupancy sensor terminals for short to 
ground, short to power supply, and open circuit:
— 1I—B

• Is wiring harness okay?

Yes

Go to next step.

No

Replace wiring harness.

3

INSPECT WIRING HARNESS BETWEEN METER 
IG 15 A FUSE AND OCCUPANCY SENSOR

• Connect negative battery cable.

• Turn ignition switch to ON position.

• Measure voltage at occupancy connector 

terminal A.

• Is voltage more than 9V?

Yes

[Present malfunction diagnosis]Go to next step.
[Past malfunction diagnosis]
Troubleshooting completed.

No

Replace wiring harness.

4

VERIFY WHETHER MALFUNCTION IS IN 
OCCUPANCY SENSOR OR SAS UNIT

• Turn ignition switch to LOCK position.

• Disconnect negative battery cable and wait for 

more than 1 minute.

• Connect all SAS unit connectors.

• Connect drive- and passenger-side pre-

tensioner seat belt connectors. (Vehicle with 
pre-tensioner seat belt)

• Connect driver and passenger-side curtain air 

bag module connectors. (Vehicles with curtain 
air bag)

• Connect driver and passenger-side side air bag 

module connectors. (Vehicle with side air bag)

• Connect passenger-side air bag module

connector.

• Connect clock spring connector.

• Connect occupancy sensor connector.

• Short occupancy sensor connector terminal B to 

ground.

• Connect negative battery cable.

• Turn ignition switch to ON position.

• Is DTC B1871 indicated?

Yes

Replace SAS unit.
(See 

T–124 SAS UNIT REMOVAL/INSTALLATION

)

No

Replace seat cushion.
(See 

S–106 FRONT SEAT DISASSEMBLY/ASSEMBLY

)

STEP

INSPECTION

ACTION

T–202

ON-BOARD DIAGNOSTIC [AIR BAG SYSTEM] 

DTC B1877, B1878, B1879, B1885

A6E817401046W09

Diagnostic procedure

DTC

B1877

Driver-side pre-tensioner seat belt system resistance high

B1878

Driver-side pre-tensioner seat belt system circuit short to power supply

B1879

Driver-side pre-tensioner seat belt system circuit short to ground

B1885

Driver-side pre-tensioner seat belt system resistance low

DETECTION 

CONDITION

Warning
• Detection conditions are for understanding DTC outline before performing inspection. 

Performing inspection with only detection conditions may cause injury due to operating error 
or damage the system. When performing inspection, always follow inspection procedure.

• Abnormal resistance (other than 1.5—3.1 ohm) detected in driver-side pre-tensioner seat belt circuit

• Malfunction in wiring harness between driver-side pre-tensioner seat belt and SAS unit

POSSIBLE 

CAUSE

• Open or short circuit in wiring harness between driver-side pre-tensioner seat belt and SAS unit

• Driver-side pre-tensioner seat belt malfunction

• SAS unit malfunction

STEP

INSPECTION

ACTION

1

INSPECT DRIVER-SIDE PRE-TENSIONER 
SEAT BELT

• Check following PID/DATA monitor, using 

SST (WDS or equivalent).
(See 

T–195 PID/DATA MONITOR TABLE

)

— DR_PTENS

• Is resistant value of driver-side pre-tensioner 

seat belt normal?
— Resistance: 1.5—3.1 ohm

Yes

Present malfunction diagnosis:

• Replace SAS unit.

(See 

T–124 SAS UNIT REMOVAL/INSTALLATION

)

Past malfunction diagnosis:

• Troubleshooting completed.

No

Go to next step.

2

INSPECT DRIVER-SIDE PRE-TENSIONER 
SEAT BELT CONNECTOR

Warning
• Handling air bag system components 

improperly can accidentally deploy air 
bag modules and pre-tensioner seat 
belts, which may seriously injure you. 
Read AIR BAG SYSTEM SERVICE 
WARNINGS before handling air bag 
system components. 
(See 

T–117 SERVICE WARNINGS

)

• Turn ignition switch to LOCK position.

• Disconnect negative battery cable and wait 

for more than 1 minute.

• Remove driver’s side B-pillar lower trim.

• Disconnect driver-side pre-tensioner seat 

belt connector.

• Is there cracking or chipping in driver-side 

pre-tensioner seat belt connector?

Yes

Replace wiring harness.

No

Go to next step.