88 k1500 305 code 43?

checked code on my 88 k1500 with a 305 auto and it was code 43. I believe I narrowed it down to the knock sensor or electronic spark control module. Which one is a better guess?

Most code 43 are caused by a unpluged sensor bad connection and plugin on wiring.
Check wiring and sensor voltage.
Post back sensor voltage with ign on sensor/sensors plugged up.