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A-2, Mil On Steady Or Won't Flash Code 12

  1. Connect Tech 1 scan tester. Start engine. Check MIL. If MIL is not flashing, go to next step. If MIL is flashing, turn ignition off. Disconnect PCM connector "D". Using test light connected to battery voltage, probe DLC test terminal No. 6. See Figure. If test light illuminated, output/field service enable circuit (DLC terminal No. 6) is shorted to ground. If test light did not illuminate, replace faulty PCM.
  2. Disconnect scan tester. Using jumper wire, ground DLC test terminal No. 6 (output/field service enable). If MIL flashes, check faulty DLC connections or faulty scan tester. If MIL did not flash, connect DVOM to DLC terminal No. 6. DVOM should read 5 volts. If reading is as specified, check for faulty PCM connection or faulty PCM. If reading is not as specified, go to next step.
  3. Turn ignition off. Disconnect PCM connector "D". Using a jumper wire, ground DLC test terminal No. 6. With test light connected to battery positive, probe PCM harness connector terminal D20 (White/Black wire). Test light should illuminate. If test light illuminated, check for faulty PCM connection or faulty PCM. If test light did not illuminate, check for open DLC test terminal "B" circuit.
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