Diagnostic Circuit Check - Minimum Function System

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Fig. 010 - Procedure for Diagnostic Circuit Check VIN C:






1982-87 VIN C (1.6L)

DIAGNOSTIC CIRCUIT CHECK

The purpose of the Diagnostic Circuit Check is to:
a. Make sure the "CHECK ENGINE" lamp is working.
b. The ECM is operating and can recognize a fault.
This is the starting point for any diagnosis.
If there are no trouble codes indicated, go to the System Performance Check.
If no additional checks are called out from the System Performance Check, go to Diagnosis by Symptom.


Fig. 009 - Chart - Diagnostic Circuit Check:





1. This checks the "CHECK ENGINE" lamp circuit. Normal operation is when "CHECK ENGINE" lamp is "on" steady.
2. This checks to see if the ECM can recognize a fault. Because the engine is not running, then there is no reference pulse and light should flash trouble code 12.
3. This checks to see if there is a problem that will set a code at curb idle for one minute.



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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.