Crappy phone pic I took, zip tie it to the back of the circuit board, tap it into the black wire and the blue wire next to the brown wire.
I agree with you they're not the best thing to use and solder is better, but honestly in that spot it's not gonna move around and if it's the ones with gel in it the connection is sealed good enough, had them there over a year with zero issues.Dint go to ground. You have to be across both wire on the harness. It's a load resistor, the way you did it didn't put the load on the proper circuit.
And those little blue things you're talking about are referred to as scotch locks, and I'd never, ever use one on anything.