I have an 88 s15 with the 4.3 and was reading a code 43 which is knock sensor or electronic spark controller problem. Truck runs real sluggish and sometimes stalls occasionally. I tested for continuity on my knock sensor and had none so I replaced it, but I've also heard that I'm supposed to get 4-5volts to the KS pigtail coming from the esc and I'm getting nothing to it at all. So I went to a salvage yard and pulled 3 esc modules (just for redundancy) and plugged them into my truck to see if I got voltage to the KS pigtail and still nothing from any of them. (Didnt have to buy them)Btw, I do have 12 volts to the esc through the pig tail and also have a good ground on the esc.