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 Metro Base, 4D Hatchback, AutomaticFACTORY OEM SERVICE PROCEDURE
Code 24, Vehicle Speed Sensor Circuit: Notes
The ECM supplies a 12-volt signal to Vehicle Speed Sensor (VSS). The VSS toggles this signal (on-and-off) indicating vehicle is moving.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- If speedometer is inoperative, this could cause Code 24.
- This checks if ECM is supplying 12 volts to VSS.
- The VSS is on the back of the instrument panel. Code 24 will set if fuel remains cut for 4 seconds or longer, engine speed is less than 4000 RPM and less than one mile an hour is sensed.
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.