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Mil Inoperative

NOTE: For circuit reference, see WIRING DIAGRAMS article.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Turn ignition off. Check IG-COIL and FI fuse (located in instrument panel fuse block). If fuses are okay, go to next step. If a fuse or both fuses are open, go to step  20.
  3. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step  10.
  4. Turn ignition on, with engine off. Using scan tool, select data display. If scan tool displays any data, go to next step. If scan tool does not display any data, go to step  10.
  5. Turn ignition off. Disconnect PCM harness connector C1. Back out PCM harness connector C1 terminal No. 17 (Purple/Yellow wire). See Figure. Using a fused jumper wire, jumper Purple/Yellow wire to ground. Turn ignition on, with engine off. Observe MIL. If MIL illuminates, go to step  18. If MIL does not illuminate, go to next step.
  6. Using a test light connected to ground, backprobe instrument cluster assembly harness connector C1 terminal No. 2 (Black/White wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  8.
  7. Turn ignition off. Disconnect instrument cluster assembly harness connector C1. Using a test light connected to battery voltage, probe instrument cluster assembly harness connector C1 terminal No. 4 (Purple/Yellow wire). Turn ignition on, then off while observing test light. If test light illuminates if ignition is turned on, go to step  19. If test light does not illuminate when ignition is turned on, go to step  9.
  8. Turn ignition off. Repair open in Black/White wire between passenger compartment fuse block and instrument cluster harness connector. After repairs, go to step  21.
  9. Turn ignition off. Repair open in Purple/Yellow wire between MIL and PCM harness connector C1 terminal No. 17 (Purple/Yellow wire). After repairs, go to step  21.
  10. Turn ignition on, with engine off. Using a test light connected to ground, backprobe PCM harness connector C1, terminals No. 2 (White/Blue wire) and No. 15 (White/Blue wire). See Figure. If test light illuminates on both terminals, go to next step. If test light does not illuminate on either terminals, go to step  13.
  11. Using test light connected to ground, backprobe PCM harness connector C3 terminal No. 20 (Black/White wire). If test light illuminates, go to step  14. If test light does not illuminate, go to next step.
  12. Turn ignition off. Repair for open in Black/White wire between the IG-COIL fuse located in fuse block and PCM harness connector C3 terminal No. 20. After repairs, go to step  21.
  13. Turn ignition off. Check for open in Light Blue/Black wire between main relay (located in relay block, near battery) and PCM harness connector C1 terminal No. 19. Repair as necessary. After repairs, go to step  21. If circuit is okay, diagnose or replace main relay.
  14. Using a DVOM, check voltage between ground and PCM harness connector C2 terminal No. 1 (Light Green wire). If voltage reading is 5 volts, go to step  18. If voltage reading is not 5 volts, go to next step.
  15. Turn ignition off. Check for short to ground in Light Green wire or in the circuit components. Repair as necessary. After repairs, go to step  21. If circuit is okay, go to next step.
  16. Disconnect PCM harness connector C1. Using a test light connected to battery voltage, probe PCM harness connector C1, terminals No. 1 (Black/Green wire), No. 13 (Black/Blue wire), and No. 26 (Black/Red wire). See Figure. If test light illuminates at each terminal, go to step  18. If test light does not illuminate at any of the terminals, go to next step.
  17. Repair affected circuit(s) for open to ground connector. After repairs, go to step  21.
  18. Turn ignition off. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to step  21.
  19. Turn ignition off. Check for faulty bulb, faulty circuit from instrument panel harness connector to MIL bulb socket, or for faulty electrical connection in instrument panel assembly. Repair as necessary. After repairs, go to step  21.
  20. Repair short to ground in IG-COIL or FI fuse circuits. After repairs, go to next step.
  21. Turn ignition on, with engine off. Observe MIL. Start engine, and continue to observe MIL. If MIL illuminates when ignition is on, and turns off after engine is started, system is okay. If MIL stays on after engine is started, check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . Diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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