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.
1990 Geo Tracker Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Chart A-2, Won't Flash Code 12 Check Engine Light On Steadily: Notes
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- If vehicle is equipped with Federal emissions, perform this step before going to next step.
- If CHECK ENGINE light goes off when ECM is disconnected, circuit No. 419 is not shorted to ground.
- This step checks for an open Blue/Yellow wire.
- This has determined that CHECK ENGINE light circuit is okay and problem is caused by a faulty ECM.
Factory Service Tools
Use the Manual With the Right Hardware
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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.