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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 272 (Supplemental Inflatable Restraint System) >> Diagnostic Tests >> Test Ac: No Communication With RCM >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

A no communication with RCM fault could be caused by damaged wiring, terminals or connectors, a faulty DLC or faulty RCM.

  1. Check RCM connector & pin for damage

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Disconnect connector C310A. Connect negative battery cable. Inspect both harness side and component side of RCM connector C310A, terminal No. 11 for damage, corrosion or dirt. See Figure . If no problem is found with connector or component, go to next step. If problems are found, repair RCM and/or connector as necessary. Retest communication to RCM. Activate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM.

  2. Check DLC connector & pin for damage

    Inspect DLC connector and terminal No. 7 (Light Blue/White wire, circuit No. 70) for damage, corrosion or dirt. See Fig 1 . If no problem is found with connector or terminal, go to next step. If problem is found, repair connector or terminal as necessary. Retest communication to RCM. Activate air bag system.

  3. Check ignition circuit for open

    Turn ignition switch to ON position. Measure voltage between ground and harness side of RCM connector C310A, terminal No. 12 (Red/White wire, circuit No. 937). If voltage is 9-16 volts, go to next step. If voltage is not 9-16 volts, repair open in Red/White wire. See WIRING DIAGRAMS  . Retest communication to RCM. Activate air bag system.

  4. Check ground circuit for open

    Turn ignition switch to OFF position. Measure resistance between sheet metal ground near RCM and harness side of RCM connector C310A, terminal No. 16 (Black/Light Blue wire, circuit No. 1203). If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair Black/Light Blue wire as necessary. Retest communication to RCM. Activate air bag system.

  5. Check circuit for open

    Measure resistance between harness side of RCM connector C310A, terminal No. 11 and DLC connector terminal No. 7 (Light Blue/White wire). If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Light Blue/White wire. Retest communication to RCM. Activate air bag system.
    NOTE: Ensure all air bag system simulators, sensor electrical connectors and RCM electrical connectors are connected prior to carrying out on-demand self-test or erroneous faults may be set.

  6. Confirm RCM fault

    Reconnect RCM connector C310A. Turn ignition switch to ON position. Perform on-demand-self-test. If scan tool can communicate with RCM during on-demand self-test, fault is corrected. Activate air bag system. If scan tool cannot communicate with RCM during on-demand self-test, replace RCM. Retest communication to RCM. Activate air bag system.
Fig 1: Identifying Data Link Connector (DLC)
G98H08170Courtesy of FORD MOTOR CO.
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