I'm installing a stereo head unit and don't have sound. This blue wire comes from the included harness and is the amp control wire. The control wire on the other connector at the unit also says amp control and isn't connected to anything. I'm assuming I have to connect the two wires and this thing (plus heat shrink wrap...?) will help. I'm unsure if I should use this or cut and strip the wires and find some wire nuts. How do I use this connector, (if it even is one)?
Big difference between a major household appliance and a car stereo, when it comes to safety and consequences of wiring things wrong. For the cooktop, the worst that could happen is killing yourself. For a car stereo, generally the worst that could happen is frying the car stereo, supposing that it isn't fused and doesn't have circuits to protect against reverse polarity or other faults.
In fact, a car stereo is a pretty excellent and safe place to start learning electrical and really where many have gotten their start.
Ive seen many cars where somebody found their place to start working with electronics. Cables twisted together and held by electrical tape, positive connections spliced to anything that measures 12V including straight to the positive battery terminal. Wires crimped by screws or other components screwed over them. Now every time I see a car burned down to the ground I know what happened.
Im not against learning on your own equipment, but maybe watch a couple youtube videos first or read some manuals online. If op doesn’t know what a bullet connector is and where it goes it means they are flying blind with possibly no understanding of a basic safety regime when working with electricity where everything that works is already good enough.
The point that I'm making is that catching fire, even in these circumstances, is extremely unlikely, especially with a somewhat modern head unit. Even going right off the positive terminal (shudder), it's much more likely to brick the deck in a way that no longer conducts electricity than it is to conduct AND resist enough to start a fire and/or dump a significant amount of current from the battery. Electrical safety and best practices are definitely important though. (OP please do not do the things that this commenter listed)
That's fair. My assumption, however, is that OP is trying to identify the connector to figure out how to properly use it. I couldn't have told you the name of the connector a couple of days ago and I've done a fair amount of PCB design, a bit of basic mains wiring, and just completely rewired my guitar. I DID know the name at one point but forgot it. I think it may have been more helpful, from your side to raise you very valid concerns to OP in a manner that offered them constructive avenues to learn further and not do horrifying things with their car electrical systems.
Seriously, thank you for speaking up on those horror shows that you've seen. I hope OP takes note and learns to do it right.