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Home >> Mazda >> 2000 >> MPV DX >> Repair and Diagnosis >> External Pages >> Different car >> Section 145 (Air Bag System) >> Diagnostic Tests >> Test M: Front Crash Sensor System Communication Error Or Sensor Internal Circuit Abnormal >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2004 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

Open or short circuit in wiring harness between front crash sensor and SAS control module, front crash sensor malfunction or SAS control module malfunction.

  1. Inspect front crash sensor

    Using scan tool, inspect PID/DATA monitor OD-F-CRSH. See PID/DATA MONITOR & RECORD  under DIAGNOSTICS. If PID readings are normal and performing present malfunction diagnosis, replace SAS control module. See SAS CONTROL MODULE  under REMOVAL & INSTALLATION. If PID readings are normal and performing past malfunction diagnosis, test is complete. If readings are not normal, go to next step.
  2. Inspect wiring harness between front crash sensor & SAS control module

    Turn ignition to LOCK position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Remove steering column cover and disconnect clockspring connector. Remove glove compartment and disconnect passenger-side air bag module connectors. On models equipped with side air bags, disconnect right and left side air bag module connectors. On models equipped with side curtain air bags, disconnect right and left side curtain air bag module connectors. On models equipped with seat belt pretensioners, remove right and left lower B-pillar trims and disconnect seat belt pretensioner connectors. On all models, disconnect all SAS control module connectors. Disconnect front crash sensor. Measure for short to ground, short to power or open circuit between SAS control module connector No. 1, terminal No. 1B and front crash sensor connector terminal "A". See Figure & Fig 1 . Measure for short to ground, short to power or open circuit between SAS control module connector No. 1, terminal No. 1C and front crash sensor connector terminal "B". If short to ground, short to power or open circuit is detected, replace wiring harness. If wiring harness is okay, replace front crash sensor. See FRONT CRASH SENSOR  under REMOVAL & INSTALLATION.
  3. Inspect SAS control module

    Turn ignition switch to LOCK position. Disable air bag system. Connect all SAS module connectors. Connect front crash sensor connector. Connect negative battery cable. Retrieve Diagnostic Trouble Codes (DTCs). See RETRIEVING DIAGNOSTIC TROUBLE CODES (DTCS)  under DIAGNOSTICS. If DTC B2296 is retrieved and performing present malfunction diagnosis, replace SAS control module. If DTC B2296 is retrieved and performing past present malfunction diagnosis, test is complete. If DTC B2296 is not retrieved, test is complete.
Fig 1: Identifying Front Crash Sensor, Seat Track Position Sensor & Seat Belt Buckle Switch Connector Terminals
G99A28902Courtesy of MAZDA MOTORS CORP.