DTC B1877, B1878, B1879, B1885


BHE080201046W12

DTC

B1877

Driver-side pre-tensioner seat belt circuit resistance high

B1878

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

B1879

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

B1885

Driver-side pre-tensioner seat belt circuit resistance low

DETECTION CONDITION

Warning
• Detection conditions are for understanding the DTC outline before performing an inspection. Performing an inspection according to only the detection conditions may cause injury due to an operating error, or damage the system. When performing an inspection, always follow the inspection procedure.
• Abnormal resistance (other than 1.5-3.1 ohms ) detected in the driver-side pre-tensioner seat belt circuit
• Malfunction in the wiring harness between the driver-side pre-tensioner seat belt and SAS unit

POSSIBLE CAUSE

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

Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT DRIVER-SIDE PRE-TENSIONER SEAT BELT

• Using the WDS or equivalent, verify the following PID/DATA monitor.
– DR_PTENS
• Is driver-side pre-tensioner seat belt resistance normal?
– Resistance: 1.5-3.1 ohms
Yes

[Present malfunction diagnosis]

• Replace the SAS unit.

[Past malfunction diagnosis]

• DTC troubleshooting completed.
No
Go to the next step.
2

INSPECT DRIVER-SIDE PRE-TENSIONER SEAT BELT CONNECTOR

Warning
• Handling the air bag system components improperly can accidentally deploy the air bag modules and pre-tensioner seat belts, which may seriously injure you. Read the service warnings and cautions before handling the air bag system components.
(See SERVICE WARNINGS.)
(SeeSERVICE CAUTIONS.)
• Turn the ignition switch to the LOCK position.
• Disconnect the negative battery cable and wait for 1 min or more.
• Remove the driver-side rear door lower trim.
• Disconnect the driver-side pre-tensioner seat belt connector.
• Is there any malfunction of the driver-side pre-tensioner seat belt connector?
Yes
Replace the air bag wiring harness.
No
Go to the next step.
3

VERIFY WHETHER MALFUNCTION IS IN DRIVER-SIDE PRE-TENSIONER SEAT BELT OR RELATED WIRING HARNESS

• Connect the leads of the SST (Fuel and thermometer checker) or apply 2-ohm resistance to driver-side pre-tensioner seat belt connector terminals A and B.
• Set the resistance of the SST (Fuel and thermometer checker) to the 2-ohm position.
• Connect the negative battery cable.
• Turn the ignition switch to the ON position.
• Using the WDS or equivalent, verify the following PID/DATA monitor.
– DSB_P_ST
• Are related wiring harnesses normal?
Yes
Replace the driver-side pre-tensioner seat belt.
No
Replace the air bag wiring harness, then go to the next step.
4

INSPECT SAS UNIT

• Turn the ignition switch to the LOCK position.
• Disconnect the negative battery cable and wait for 1 min or more.
• Connect the driver-side pre-tensioner seat belt connector.
• Are DTCs B1877, B1878, B1879 and/or B1885 indicated?
Yes

[Present malfunction diagnosis]

• Replace the SAS unit.

[Past malfunction diagnosis]

• DTC troubleshooting completed.
No
DTC troubleshooting completed.