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.
DTC 49, Service Throttle Soon Light Circuit Fault: Notes
SERVICE THROTTLE SOON light should always light when ignition is on and engine is not running for 2 seconds. PCM controls SERVICE THROTTLE SOON light by providing a ground path. DTC 49 will set when:
- Ignition voltage on SERVICE THROTTLE SOON light control circuit when PCM is requesting SERVICE THROTTLE SOON light on.
Or
- No ignition voltage on SERVICE THROTTLE SOON light control circuit when PCM is requesting SERVICE THROTTLE SOON light off.
PCM will default to MIL will not light, but a current and history DTC 49 will set.
- This step checks PCM's ability to command SERVICE THROTTLE SOON light.
- This step determines if an open is present in ignition feed circuit or SERVICE THROTTLE SOON light control circuit.
NO RELATED
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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.