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No Response From Powertrain Control Module (PCI Bus)

  1. Turn ignition on. Using scan tool, select BODY, then BCM. Determine if communication was able to be established. Select BODY, then DOOR MODULES. Determine if communication was able to be established. Select ANTI-LOCK BRAKES. Determine if communication was able to be established. Select BODY, then ELECTRO-MECHANICAL CLUSTER. Determine if communication was able to be established. Select PASSIVE RESTRAINTS, then AIR BAG. Determine if communication was able to be established. If communication is possible with all modules, go to next step. If communication cannot be established with one or more modules, go to PCI BUS COMMUNICATIONS FAILURE . Perform POWERTRAIN CONTROL MODULE VERIFICATION TEST  under VERIFICATION TESTS.
  2. Disconnect Gray PCM connector C3. See Figure. Use Scope Input Cable (CH7058), Cable-To-Probe Adapter (CH7062) and Red and Black test probes. Connect scope input cable to channel one connector on scan tool. Attach Red and Black test probes and cable-to-probe adapter to scope input cable. Select scan tool STANDALONE function. Select LAB SCOPE. Select LIVE. Select 12 VOLT SQUARE WAVE. Press F2 for scope display. Press F2 and use down arrow to select voltage range to 20 volts. Press F2 after selecting 20 volts. Connect Black test probe lead to ground and Red test probe lead to PCM connector terminal No. 30 (Yellow/Violet wire). See Figure. Turn ignition on. Observe voltage readings on scan tool. If reading pulses from zero to approximately 7.5 volts, go to next step. If reading is steady at zero volts, repair PCI bus circuit (Yellow/Violet wire at PCM, Yellow/Violet/Gray wire at diagnostic junction port) between PCM and diagnostic junction port. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. Perform POWERTRAIN CONTROL MODULE VERIFICATION TEST  under VERIFICATION TESTS.
  3. Replace PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
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