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2008 - MX-5 - Restraints

DTC B1428



DTC

B1428

Seat belt warning light circuit open

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.

  • Malfunction in the seat belt warning light circuit

POSSIBLE CAUSE

  • Instrument cluster malfunction

  • Malfunction of the connectors between the instrument cluster and SAS control module

  • Open or short circuit in the wiring harness between the battery and the instrument cluster

  • Open or short circuit in the wiring harness between the instrument cluster and SAS control module

  • SAS control module malfunction


Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT FOR CONTINUITY BETWEEN BATTERY FUSE AND INSTRUMENT CLUSTER
  • Connect negative battery cable.

  • Turn the ignition switch to the ON position.

  • Measure the voltage at instrument cluster connector terminal 2A.

  • Is the voltage 9 V or more?

Yes

Go to the next step.

No

Repair the related wiring harness.

2

INSPECT WIRING HARNESS BETWEEN INSTRUMENT CLUSTER AND SAS CONTROL MODULE

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 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.

  • Disconnect the SAS control module connector.

  • Disconnect the instrument cluster connector.

  • Inspect the wiring harness between SAS control module terminal 1X and instrument cluster terminal 2A for the following:

    • Short to ground

    • Short to power supply

    • Open circuit

  • Is the wiring harness normal?

Yes

Go to the next step.

No

Replace the air bag wiring harness.

3

INSPECT SEAT BELT WARNING LIGHT
  • Connect the instrument cluster connector.

  • Ground instrument cluster connector terminal 1E using a jumper wire.

  • Turn the ignition switch to the ON position.

  • Does the seat belt warning light illuminate?

Yes

Replace the SAS control module.

(See SAS CONTROL MODULE REMOVAL/INSTALLATION.)

No

Replace the instrument cluster.

(See INSTRUMENT CLUSTER REMOVAL/INSTALLATION.)




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