Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Procedure
This diagnostic procedure is used to test and service the EEC-IV system. It is divided into 2 test formats: QUICK TEST , a functional system test, and CIRCUIT TESTS , a number of specific circuit and component tests. To test and service EEC-IV system, perform the QUICK TEST first.
If vehicle passes KEY ON/ENGINE OFF (KOEO) , KEY ON/ENGINE RUNNING (KOER) , and CONTINUOUS SELF-TESTS of QUICK TEST without running any CIRCUIT TESTS , the EEC-IV system is okay. Problem exists somewhere else besides the EEC-IV system. If QUICK TEST fails, perform only those tests that are specified by the failed step.
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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.
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