This report applies to the common heat-sink-style GM Gen-3 4.8/5.3/6.0 truck smart coil commonly identified as:
ACDelco D585
GM 10457730
Delphi GN10119
Wells C1251
Standard Motor Products UF262
Physical appearance alone is not sufficient because LS coil families use different housings and some online pinouts mix coil types. Verify the molded cavity letters and preferably the part number on the actual coil before wiring.
Four-pin connector pinout
Viewed by the molded cavity letters, not by an assumed left-to-right photo orientation:
Mating connector identifiers reported by MegaManual are GM 12580353 / Delphi 15439568. Connector suppliers may sell these under application descriptions rather than those bare numbers.
Research confirms the D585 pinout: A power ground, B signal ground, C trigger, D switched 12 V. It charges with a >4 V high signal and sparks on the falling edge; start around 3.5 ms dwell at 14 V.
Important finding: firing both coils at every trigger would approach 93% dwell duty at 8000 RPM, so the controller needs alternating cylinder outputs rather than permanently tied triggers. Full details: D585 Coil Research.
I’ll evaluate strategies that work with two potentially identical pickup events—startup wasted spark, trial-and-confirm phasing, crank-acceleration detection, target asymmetry, and adding an index sensor—then rank them by safety and implementation risk.
Startup and Phase IdentificationProblem definition
The Rotax 593 has one VR pickup and appears to produce two crank-reference events per revolution, about 180° apart. If those events are electrically and geometrically identical, the controller knows that one cylinder is approaching its firing position but cannot initially know whether that event belongs to the MAG or PTO cylinder.
This is not a four-stroke cam-phase problem: each two-stroke cylinder fires once per crank revolution. It is a cylinder-label problem caused by two symmetric crank events and two separate single-output coils.
If the targets are truly identical, no passive algorithm can identify MAG versus PTO from the first pulse alone. Additional information must come from target asymmetry, another sensor, store...