Code 43

I have a code 43 on my 89 astro. Wondering how I find the exact problem. In the manual a Code 43 is either low voltage in EST (electronic spark timing) or ESC (electronic spark controller). On a website I went to it said a Code 43 was the ECM not detecting a knock signal at near wide open throttle at coolant temperature above 194 degrees. I have never owned a vehicle with so many sensors before and I feel a bit over-whelmed when this stuff happens. Does it involve testing with a volt meter or is there another way. Any help is much appreciated. Thanx

Wide open throttle above 194 degrees? I discern from your nickname that you are unlikely to drive your van at wide open throttle. Something seems akimbo about that code description.

My Haynes manual indicates code 43 for the ESC only. Otherwise known as the knock sensor.
If you have a digital multimeter you can certainly test the sensor. If it's the original sensor on your '89 it's a fair bet it's given up the ghost.
However, the knock sensor on an '89 gets pretty gunked up. I know, I have an '89 too. For starters you could clean it up, and make sure the connector is making good contact. if that doesn't do it, the sensor is about 29 bucks to replace.

I had a knock sensor go and give that code too.

Thanks for your replies. I was getting some of the code descriptions from the manual that came with my code reader and some from a website. Glad I asked the question here. Take care.