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2008 - MX-5 - Restraints

DTC B1877, B1878, B1879, B1885



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 body 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.

  • Resistance other than 1.3—4.7 ohms detected in driver-side pre-tensioner seat belt circuit

  • Malfunction in the wiring harness between driver-side pre-tensioner seat belt and SAS control module

POSSIBLE CAUSE

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

  • Driver-side pre-tensioner seat belt malfunction

  • SAS control module malfunction


Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT DRIVER‐SIDE PRE-TENSIONER SEAT BELT
  • Using the M-MDS, verify the following PID/DATA monitor.

    (See PID/DATA MONITOR TABLE.)

    • RES_PT_D

  • Is the driver-side pre-tensioner seat belt resistance normal?

    • Resistance: 1.3—4.7 ohms

Yes

Replace the SAS control module.

(See SAS CONTROL MODULE REMOVAL/INSTALLATION.)

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 air bag system service warnings and cautions before handling the air bag system components.

    (See AIR BAG SYSTEM SERVICE WARNINGS.)

    (See AIR BAG SYSTEM SERVICE CAUTIONS.)

  • Turn the ignition switch to the LOCK position.

  • Remove the battery cover.

  • Disconnect the negative battery cable and wait for 1 min or more.

    (See BATTERY REMOVAL/INSTALLATION [LF].)

  • Remove the back 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.

  • Are DTCs B1877, B1878, B1879, and/or B1885 indicated?

Yes

Go to the next step.

No

Replace the driver-side pre-tensioner seat belt.

(See SEAT BELT REMOVAL/INSTALLATION.)

4

INSPECT WIRING HARNESS BETWEEN DRIVER‐SIDE PRE-TENSIONER SEAT BELT AND SAS CONTROL MODULE
  • Turn the ignition switch to the LOCK position.

  • Remove the battery cover.

  • Disconnect the negative battery cable and wait for 1 min or more.

    (See BATTERY REMOVAL/INSTALLATION [LF].)

  • Remove the column cover.

  • Disconnect the clock spring connector.

  • Remove the glove compartment.

  • Disconnect the passenger-side air bag module connector.

    (See PASSENGER-SIDE AIR BAG MODULE REMOVAL/INSTALLATION.)

  • Disconnect the driver and passenger-side seat connectors.

  • Remove the back trim.

  • Disconnect the driver and passenger-side pre-tensioner seat belt connectors.

  • Inspect the wiring harness between SAS control module terminal 2A and driver-side pre-tensioner seat belt terminal A, SAS control module terminal 2D and driver-side pre-tensioner seat belt terminal B for the following:

    • Short to ground

    • Short to power supply

    • Open circuit

  • Is the wiring harness normal?

Yes

Replace the SAS control module.

(See SAS CONTROL MODULE REMOVAL/INSTALLATION.)

No

Replace the air bag wiring harness.




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