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A-2, Mil On Steady Or Won't Flash Code 12: 2.2L

  1. Install Tech 1 scan tester. Turn ignition on with engine off. MIL should come on. If MIL is off, refer to A-1, MIL INOPERATIVE. If MIL is on, check if scan tester is displaying scan data. If scan data is displayed, go to next step. If no scan data is displayed, check for open, short to ground or short to voltage in serial data circuit. If circuit is okay, check for faulty EPROM or PCM.
  2. Start engine. Using Tech 1 scan tester, command MIL off then on. If MIL does not respond as commanded, go to next step. If MIL responds as commanded, check for trouble codes. Diagnose any trouble code(s) present. Refer to appropriate TESTS W/CODES article in the ENGINE PERFORMANCE. If trouble code(s) is not present, system is operating normally.
  3. Turn ignition off. Disconnect PCM connectors. Turn ignition on. MIL should be off. If MIL did not come on, repair short to ground in circuit No. 419 (Brown/White wire). If MIL came on, check EPROM for proper installation. If EPROM is installed properly, replace PCM using original EPROM. Start engine. Using scan tester, command MIL on then off. If MIL responds as commanded, system is now okay. If MIL does not respond as commanded, replace EPROM.
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