Have you checked your ground?

Everytime I see this I want to scream! Grounds are not rocket science or difficult, if your component doesn't come on and you verified you have 12 volts to it,provide a ground from the component to a good ground. Did it come on,you just verified the ground is your problem. Component works but not like it should ground 1 lead of your meter to a good ground,hook the other end to where your component grounds,read your meter is it reading more than .5 volt? You've got a sketchy ground clean it. You can do the same test on the positive side 1 meter lead to good positive, 1 meter lead to the component. The component does have to powered on and running to check volt drop on either lead. There's going to be arguments about how much drop is acceptable,rule of thumb is .1 volt per connection,if you have less than 1/2 volt drop,move on its not your problem. In the car I have a cigarette lighter plug with nothing attached,I can plug it in the cigarette lighter,now I have a ground wire and a hot wire,cigarette lighter is high draw circuit,sufficient for anything I've had to test. Busy will come back later to edit and punctuate. Have a great day. Components grounded to another component like alternator,check alternator body to block for volt drop,distributor body to block etc.

I used to ask questions of the electrical Vehicle System Engineer all the time. I had him on speed dial from the back barn to his pager.

"Hey Jerry" I'd say. "I've got this problem -

"Bad ground" he'd say.

"You didn't even let me finish!"

"I know. Start by checking the grounds".

Usually he was right.

K