2002 Jeep Wrangler SE, AutomaticFACTORY OEM SERVICE PROCEDURE

No Response From Powertrain Control Module (PCI Bus)

NOTE: After all repairs in this test, perform POWERTRAIN VERIFICATION TEST  under VERIFICATION TESTS.

Possible Causes:

  • PCM PCI No Response
  • PCI Bus Circuit Open
  • Power Control Module

Testing

  1. Turn ignition on. Using scan tool, attempt to communicate with instrument cluster and air bag control module. If any communication exists, go to next step. If no communication exists, go to PCI BUS COMMUNICATION FAILURE  .
  2. Using scan tool, check Powertrain Control Module (PCM) Diagnostic Trouble Codes (DTC). This is to check PCM power and ground circuits. If scan tool will read PCM DTCs, go to next step. If scan tool will not read PCM DTCs, but will start, go to NO RESPONSE FROM POWERTRAIN CONTROL MODULE (SCI ONLY)  . If scan tool will not read PCM DTCs and engine does not run, see NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
  3. Turn ignition off. 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 PCM connector C3 terminal C30, 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, replace PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. If voltage remains at zero volts, repair open Violet/Yellow wire.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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