This is about my son's 2004 Honda Civic LX. On occasion, a turn of the key won't start the engine. Lights and other stuff work, as they would if key were in the "accessory" position -- just not the engine. No click of starter solenoid. After several turns of the key it starts, once in a while as many as 20, but usually only 3 or 4. Two weeks ago he got a new battery.
And this is odd: It seems to be dependent to how long it has sat. My son works at his apartment and shops "big," so that he has groceries for two weeks. If the car has sat that long, it won't start. Taking it in to the shop is useless because if he tries to start the car soon after pulling in, of course, it starts.
I am thinking a cheap test would be a starter relay. But the various sites I have seen have different relay locations. For example,
Anyway, can someone point me to a good 2004 Civic LX diagram?