new battery, starter, coils, wires - still won't start.
 

Okay, I'm at my wits end here. I have an 04 that doesn't want to start. If I turn the key to the On position, everything works. Headlights, radio, dash lights, etc. I turn the key and all I get is silence. No clicks, grinds, squeals, nothing. Definitely not the sound of a car trying to start.

Last week when this happened I was able to get it to start with a jump and it started right away. Today, no such luck. Hooked up jumper cables and no change.

I've not done anything with the alternator, but I don't think that's the issue. What else could it be?

Test the starter relay. If it's fine, disconnect the battery terminals, clean the clamps and posts thoroughly, re-connect, hook the jumper cables back up, and give it a shot.

Basically, electrical power isn't getting to the starter, and it's either a dead battery, battery connections are corroded/failing, or relay failure.

Where can I find this magical starter relay?

In the fuse box under the hood behind the driver's side headlight. Remove the cover and flip it over, there is a diagram of what relays and fuses are what. It's about the center of the box.

a blown engine control fuse will give the same symptom.

An update for anyone interested/following. I put a battery terminal shim on my battery terminals and the car is firing up great. Seems the connection to the battery was just loose.

I found the relays, wasn't really sure how to test them. Need to buy a new one anyway since in trying to get my headlight relay out, I cracked it's casing. Still appears to be working, but I imagine it's a ticking time bomb.

Thanks for the help folks. Nice to finally have it working reliably again.

Just a heads up. If you hear the starter relay clicking/tripping, it usually means it's working. One trip, no start = bad battery and multiple consecutive trips = issue with starter. If there is no tripping noise, you could have a dead battery, bad wiring, or faulty relay.
Not sure if this is 100% all the time but has helped me in the past.