05/08/2026 6:12 am
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Automotive Q&A
Output-speed data drops to zero for one frame during a 2–3 shift
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A 2012 Sonata has an occasional harsh 2–3 shift and P0722 history. Input-speed and engine-speed data remain smooth, but output speed falls to zero for one frame when the transmission moves on its mounts. The sensor has correct supply and ground at rest, and the connector is dry.
Would you scope the sensor at the transmission and module simultaneously, or inspect internal components first?
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06/08/2026 9:22 am
Capture the signal at both ends before considering internal work. Use two channels with a common time base and reproduce the load condition safely. If the dropout appears at the sensor output, verify supply and ground during the event and inspect the sensor or target. If it remains clean at the transmission but disappears at the module, the harness or connector is at fault.
Load the harness in the same direction as powertrain movement and inspect clips near brackets. A scan-tool frame shows the symptom, but the synchronized waveform identifies where it is lost.
Topic starter
07/08/2026 10:11 am
The transmission-side waveform stayed clean while the module-side channel opened as the engine rolled. A conductor had rubbed through inside a clip below the battery tray. Repairing and rerouting that section removed the dropout and the shifts remained normal.