Diagnostic Aids

Because coil driver gets its power from coil, check ignition feed circuit to ignition coil for opens, including coil fuse.

Fig 1: Code 41 Schematic (5.7L) Opti-Spark Ignition System Open Or Shorted EST Circuit

Fig 2: Code 41 Diagnostic Flow Chart (5.7L) Opti-Spark Ignition System Open Or Shorted EST Circuit