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Home >> Infiniti >> 1995 >> Q45 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests 4.5L >> Computerized Engine Controls >> Engine Control Module (ECM) >> Power Circuits
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Power Circuits

  1. Turn ignition switch to ON position. Using a voltmeter, check for battery voltage between chassis ground and ECM terminals as follows:
    • On Q45, terminal No. 45. See Figure .

    If battery voltage is not present, check fusible link and fuse "G".

  2. Turn ignition switch to OFF position. Using a voltmeter, check for battery voltage between chassis ground and ECM terminals as follows:
    • On Q45, terminal No. 58

    If battery voltage is not present, check fusible link and wiring. Fusible link also supplies power for fuel injectors.

  3. Turn ignition switch on and then off. Using a voltmeter, check for battery voltage between chassis ground and ECM terminals as follows:
    • On Q45, terminals No. 49, 59 and 109.

    With ignition on, battery voltage should be present. When ignition switch is turned to the OFF position, battery voltage should be present for approximately 2-3 seconds and then zero volts should be present. If battery voltage is not as specified, check ECCS relay.

  4. Connect voltmeter between chassis ground and ECM terminal No. 43. Turn ignition switch to START position. Battery voltage should be present only when ignition switch is in START position. If voltage is not present, check for blown fuse and defective ignition switch.
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