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No Response From Air Bag Control Module

WARNING: When servicing air bag system, DO NOT reconnect battery before turning ignition on and ensuring no one is in vehicle. Air bag may deploy.
NOTE: After all repairs in this test, perform AIR BAG VERIFICATION TEST  under VERIFICATION TESTS.

Possible Causes:

Testing

  1. Ensure battery is fully charged. Turn ignition off. Disconnect negative battery cable. Wait 2 minutes. Disconnect Yellow 22-pin Air Bag Control Module (ACM) connector. See Figure . Turn ignition on. Connect negative battery cable. Using test light connected to ground, probe ACM harness connector terminals No. 17 (Light Green/Yellow wire) and No. 20 (Dark Blue/Yellow wire). If test light illuminates at both terminals, go to next step. If test light does not illuminate at one or both terminals, repair open circuit(s) between fuse block and ACM. See WIRING DIAGRAMS  .
    NOTE: Ensure other modules communicate on PCI bus before continuing. If one module does not communicate, go to appropriate test. If no PCI communication exists, go to PCI BUS COMMUNICATION FAILURE  .
  2. Check resistance between ACM harness connector terminal No. 10 (Black/Pink wire) and ground. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Black/Pink wire or poor connection to ground, on center of instrument panel.
  3. Connect Scope Input Cable (CH7058) to channel one connector on scan tool. Connect Red and Black leads, and Cable-to-Probe Adapter (CH7062) to scope input cable. Go to next step.
  4. Using scan tool, select PEP MODULE TOOLS, LAB SCOPE, LIVE, then 12-VOLT SQUARE WAVE. Press F2 for scope. Press F2 again and use down arrow to set voltage range to 20 volts. Press F2 again. Go to next step.
  5. Connect Black lead to ground. Connect Red lead to ACM connector terminal No. 18, PCI bus circuit (Violet/Yellow wire). See Figure . Turn ignition on. Observe voltage display on scan tool lab scope. If voltage pulses from zero to about 7.5 volts, go to next step. If voltage remains at zero volts, repair open Violet/Yellow wire.
  6. If no other problems are found, replace ACM. See AIR BAG CONTROL MODULE  under REMOVAL & INSTALLATION.
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