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, StandardFACTORY OEM SERVICE PROCEDURE
Code 41, Ignition Signal Circuit No Signal: Notes
ECM tach signal is 12 volts that varies as ignition coil is toggled to ground. The ECM uses this signal to pulse fuel injector. This code sets if there is no signal or is constant voltage on the line.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This checks for battery voltage on signal line.
- This checks noise suppressor for open.
- This checks for toggling voltage signal.
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.