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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 45 (Air Bag System) >> Diagnostic Tests >> Test A: Air Bag Warning Light On Continuously-RCM Disconnected Or Inoperative >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2002 Mazda B4000, 2002 Mazda B3000, and 2002 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.

An AIR BAG warning light that is continuously illuminated may be caused by disconnected RCM, damaged battery or ignition circuit, loss of ground circuit to RCM, inoperative RCM or faulty shorting bar or camming beam in connector.

  1. Check for hard or intermittent DTC

    Turn ignition switch to off position. Connect scan tool to DLC. See USING SCAN TOOL  under DIAGNOSTICS. Turn ignition switch to RUN position. Retrieve and record any continuous DTCs. See RETRIEVING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  . If continuous DTCs were retrieved, go to step  3 . If on-demand DTCs were retrieved, go to diagnostic trouble code identification table for direction to appropriate test. See DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION  table. If no DTCs were retrieved, go to next step.
  2. Check RCM connection

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING & ACTIVATING AIR BAG SYSTEM  . Access Restraints Control Module (RCM). See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. Ensure RCM connector is fully connected and Red locking tab is engaged. If RCM connector is fully connected and Red locking tab is engaged, go to next step. If RCM connector is not fully connected and/or Red locking tab is not engaged, reconnect connector and engage locking tab. Go to step  7 .
    NOTE: Shorting bars may be accessed by prying out Blue cover from harness side of connector.
  3. Check RCM connector

    Turn ignition switch to OFF position. Access Restraints Control Module (RCM) and disconnect connector. See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. Inspect RCM, component side of connector, for worn or damaged camming beam and/or any foreign material. See Fig 1 . Inspect RCM connector for worn, damaged or dislodged shorting bar at terminals No. 20 and No. 21. See Fig 1 & Fig 2 . If camming beams and shorting bars are okay, go to next step. If camming beams and shorting bars are defective, repair or replace as necessary and go to step  7 .
  4. Check RCM ignition circuit connection

    Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition switch to RUN position. Measure voltage between sheet metal ground near RCM and RCM harness connector terminal No. 2 (Black/Light Green wire, circuit No. 364). See Fig 2 . If voltage is 9-16 volts, go to next step. If voltage is not 9-16 volts, repair open in Black/Light Green wire. Also, check fuse No. F2.2 (10-amp or 20-amp depending on model) located in instrument panel fuse block. See WIRING DIAGRAMS  . Go to step  7 .
  5. Check ground circuit for open

    Turn ignition switch to OFF position. Measure resistance between sheet metal ground near RCM and RCM harness connector terminal No. 21 (Black/Orange wire, circuit No. 649). If resistance is less than 10 ohms, go to next step. If resistance is more than 10 ohms, repair open in Black/Orange wire and go to step  7 .
  6. Check for short to ground

    Measure resistance between RCM harness connector terminals No. 20 (Black/Yellow wire, circuit No. 608) and No. 21 (Black/Yellow wire). If resistance is less than 5 ohms, repair short to ground in Black/Orange wire. Go to next step. If resistance is more than 5 ohms, replace RCM and go to next step.
  7. Check for additional DTCs

    Refer to continuous DTCs recorded in step  1 . If any continuous DTCs were retrieved, go to diagnostic trouble code identification table for direction to appropriate test. DO NOT clear any DTCs until all DTCs have been resolved. See DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION  table. If no DTCs were retrieved, reconnect air bag system. Activate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Prove out system. See PROVE OUT SYSTEM  under DIAGNOSTICS. Clear all DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS.
    Fig 1: Identifying RCM Connector Camming Beams & Shorting Bars
    G99H00817Courtesy of MAZDA
    Fig 2: Identifying Restraints Control Module (RCM) Connector
    G99I00156Courtesy of MAZDA