2002 Jeep Wrangler X, AutomaticFACTORY OEM SERVICE PROCEDURE

No Response From Powertrain Control Module (SCI Only)

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

Possible Causes:

  • SCI Transmit Circuit Shorted To Ground
  • Check PCM Powers And Grounds
  • Controller Anti-Lock Brake
  • SCI Transmit Circuit Shorted To Ground
  • SCI Receive Circuit Shorted To Ground
  • SCI Receive Circuit Open
  • SCI Transmit Circuit Open
  • Powertrain Control Module

Testing

  1. Check Powertrain Control Module (PCM) power and ground circuits. See CHECKING POWERTRAIN CONTROL MODULE POWER & GROUND CIRCUITS  . If problem is not found, go to next step. If any problem is found, repair as necessary and recheck.
  2. If vehicle is equipped with anti-lock brakes, go to next step. If vehicle is not equipped with anti-lock brakes, go to step  5 .
  3. Turn ignition off. Disconnect PCM connector C3. See Figure . Remove scan tool from Data Link Connector (DLC). Check resistance between PCM connector C3 terminal C27 (Pink wire) and ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, go to step  6 .
  4. Turn ignition off. Disconnect 25-pin Controller Anti-Lock Brake (CAB) connector. See Figure . Check resistance between CAB harness connector terminal No. 20 (Pink wire) and ground. If resistance is less than 5 ohms, repair short to ground on Pink wire. If resistance is 5 ohms or more, replace CAB. See CONTROLLER ANTI-LOCK BRAKE  under REMOVAL & INSTALLATION.
  5. Turn ignition off. Disconnect PCM connector C3. See Figure . Remove scan tool from Data Link Connector (DLC). Check resistance between PCM connector C3 terminal C27 (Pink wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Pink wire.
  6. Check resistance between PCM connector C3 terminal C29 (Light Green wire) and ground. See Figure . If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Light Green wire.
  7. Check resistance of Light Green wire between PCM connector C3 terminal C29 and DLC terminal No. 6. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Light Green wire.
  8. Check resistance of Pink wire between PCM connector C3 terminal C27 and DLC terminal No. 7. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Pink wire.
  9. If no other problem is found, replace PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION.
Factory Service Tools

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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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