In my continuing effort to solve the code 43 mystery, I decided to physically check the knock sensor. Well there is one black plug that is connected to it, and there is another tan plug hanging next to it! The screwed up thing is I've scanned the car with each one plugged in, and it gave 1 knock count each way. For those who don't know, this is an '89 firebird with an 80-85 305 and the stock TBI and a tune-up and replacement of the esc still haven't cured my code 43.

 

There are two devices with identical connectors in very close proximity to each other. The one in the engine block (lower of the two) is the knock sensor, the one in the cylinder head (higher of the two) is the fan switch.

Not sure about your app, but I'd suspect the tan wire is the fan switch and the black wire is the knock sensor.

 

I had a suspicion of that, but I dont see how I got a knock reading both ways. The scanner probably just f-ed up. I think you are right about the connector. Thanks