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Home >> Chevrolet >> 1992 >> Forward Control 4.3 Z, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Diesel >> Self-Diagnostic System >> Diagnostic Procedure >> Diagnostic Procedure

Diagnostic Procedure

  1. Ensure all engine systems NOT related to the Diesel Electronic Control (DEC) system are operating properly. DO NOT  proceed with testing unless all non-DEC system problems are repaired.
  2. ALWAYS begin diagnosis with checking diagnostic circuit to determine if DEC system and ECM are working properly. See DIAGNOSTIC CIRCUIT CHECK  chart in this article. If trouble codes (other than Code 12) are displayed, determine if they are hard or intermittent trouble codes.
  3. A hard code is present while working on vehicle, and problem condition persists. Hard codes will cause SERVICE ENGINE SOON light to come on.
  4. An intermittent code does not reset itself and is NOT present while working on vehicle. Intermittent codes are often caused by loose connections. SERVICE ENGINE SOON light will go out 10 seconds after fault goes away. For intermittent diagnostic procedures, see TESTS W/O CODES article.
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