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.
Test Description
Code 24 will set if the following conditions exist for at least 3 seconds:
- Circuit No. 437 voltage is constant.
- Engine speed is 900-4400 RPM.
- Less than 2% throttle opening.
- Low load condition (low airflow).
- Transmission not in Park or Neutral.
The above conditions are met during a road load deceleration.
- This monitors ECM voltage on circuit No. 437. With wheels turning, pulsing action will result in varying voltage. Variation will be greater at low wheel speeds to an average of 4-6 volts at about 20 MPH.
- A voltage of less than one volt at ECM connector indicates that circuit No. 437 is shorted to ground. Disconnect circuit No. 437 at VSS. If voltage now reads above 10 volts, VSS is faulty. If voltage remains less than 10 volts, circuit No. 437 wire is grounded. If circuit No. 437 is not grounded, check for faulty ECM connector or ECM.
- A steady 8-12 volts at ECM connector indicates circuit No. 437 is open or faulty VSS.
- This is a normal voltage that indicates a possible intermittent condition.
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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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