[Blue Bowtie]

If the KS detects a detonation event, and signals the ESC, the ESC will retard timing. That is normal system operation, and will not set an error code.

If the KS is reading false knocks, or the ESC wiring is subjected to EMI, RFI from ignition wires, or poor connections, the system can interpret that as a regular detonation and act accordingly. It would still not set a code. You'll get an error code (42) is the ESC loses communication with the ECM oe HEI switching module in the distributor, or if the KS provides no signal to it. The 3.9K resistor will "fool" the ESC into thinking that a KS is connected, but is quiet and recieving no knock signals.

The ESC retards timing in steps, then recovers in steps. The attack and recovery rates are fairly fast. If the KS is presenting random signals at lower RPMs, the timing at lower RPMs may be all over the place. You can confirm this with a timing light. Usually, once the ESC is active the timing at idle will jump to around 20° BTC and remain fairly stable. If it is jumping all over, the ESC could be acting upon a failing KS or electrical noise in the system.