Nissan 100NX N14 silhouetteN14

Trouble Diagnoses — Diagnostic Procedure

EF & EC-423prose procedure
Continued from EF & EC-422

Diagnostic Procedure

  1. 1
    Before connecting or disconnecting the E.C.U. harness connector to or from any E.C.U., be sure to turn the ignition switch to the "OFF" position and disconnect the negative battery terminal in order not to damage E.C.U. as battery voltage is applied to E.C.U. even if ignition switch is turned off. Failure to do so may damage the E.C.U.
    CAUTION: battery voltage is applied to E.C.U. even if ignition switch is turned off. Failure to do so may damage the E.C.U.
    Illustration of a battery with the negative cable being disconnected (curved arrow showing removal of the negative terminal clamp). Labeled "BATTERY".
    SEF289H
  2. 2
    When connecting E.C.U. harness connector, tighten securing bolt until red projection is in line with connector face.
    E.C.U. (control unit) with harness connector. Callout arrow points to "Red projection" at top, and "Protector" at the connector base. Shows the securing bolt area for tightening.
    SEF725H
  3. 3
    When connecting or disconnecting pin connectors into or from E.C.U., take care not to damage pin terminals (bend or break).
    E.C.U. connector pin terminals with two examples below: a bent pin labeled "Bend" and a broken pin labeled "Break".
    SEF291H
  4. 4
    Make sure that there are not any bends or breaks on E.C.U. pin terminal, when connecting pin connectors.
  5. 5
    Before replacing E.C.U., perform E.C.U. input/output signal inspection and make sure whether E.C.U. functions properly or not. (See page EF & EC-621.)
    Cartoon-style illustration of an old E.C.U. unit ("OLD ONE") with a speech bubble reading "Perform E.C.U. input/output signal inspection before replacement". Shows two E.C.U. units.
    SEF330D
  6. 6
    After performing this "Diagnostic Procedure", perform E.C.C.S. self-diagnosis and driving test.
    E.C.U. with "RED L.E.D." callout on left, and on the right a "CHECK" engine warning light labeled "Check engine light".
    SEF621K
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See also

EF & EC-621Electrical Components Inspection

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