This demonstration guide answers one field question about a module that opens spark when a switch disagrees. Measurements come before parts, and the notes are not a generic equipment FAQ.
Diagnose before replacing parts
Start with spark with the interlock series closed. That reading separates a module that opens spark when a switch disagrees from adjacent faults that share the same complaint.
If the measurement is out of spec, treat the safety module as the primary path. If it is in spec, do not replace the safety module just to complete a parts list.
Repair the failed system
The usual correction is the safety module, installed to the documented spec for this complaint.
A demonstration shop records the finding so the next technician is not repeating a guess about a module that opens spark when a switch disagrees.
Stop before you make it worse
Do not bypassing the module to "make it start in any gear". That shortcut hides the original measurement and creates a second failure.
If the machine still fails after the safety module is corrected, convert the visit to a broader diagnosis rather than stacking parts.
Written and published by Ridgeline Small Engine.