Hey guys. I have a 2000 blazer 4.3 4door 4x4 I went to start it and nothing happened I could here the relay click and that's it checked batt volts have lots replaced relay. Still nothing. I can make the starter turn by jumping it but it just spins does not engage. When I turn the key it does not even spin any ideas

 

Even though you show voltage, the battery could still be bad under load. Or, you could have corrosion in your battery cable(s). An auto parts store can do a load test on your battery. Once you have confirmed your battery is good, do a starter voltage drop test (google a video on this by Dan Sullivan).

 

So just an update. I used a test light to check power at the starter. There was. I then checked the signal wire had a buddy turn the key to start and there was power there to so that means everything befor the starter is good and working the way it should change the starter and started my truck no problem. Thanks for the for the help.