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.
Code 24, Vehicle Speed Sensor - 1992 With 4L80-E Transmission: Notes
Vehicle speed sensor (VSS) circuit consists of a magnetic induction type sensor, VSS buffer (DRAC) module and wiring. Gear teeth pressed on the outside diameter of the output carrier assembly induce an alternating current in the sensor. On 2WD vehicles, current is transmitted to a DRAC module where it is passed on to ECM. DRAC compensates for various axle ratios and converts signal to a square wave for use by the speedometer, cruise control and anti-lock brake system.
Since vehicle speed is taken from transfer case on 4WD vehicles, transmission vehicle speed sensor signal on these units goes directly to PCM. Code 24 will set when vehicle speed is less than 200 RPM for 1.5 seconds while engine speed is greater than 3000 RPM. Park/Neutral is not selected. If input speed sensor is not operational at start up, vehicle speed sensor may read zero.
- This test checks vehicle speed sensor signal to PCM.
- This test checks vehicle speed sensor signal to DRAC.
- This test verifies vehicle speed sensor signal.
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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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