*EDIT* post title was a typo; this is a 2003 model, not a 2001.

Car details:
2003 Accord LX
Manual
4-Cylinder

Problem details:

When turning the key and pressing the clutch pedal, one of the relays under the left kick plate buzzes. Engine won’t turn over. Approximately 1 out of 30 times, the engine will start normally. This started soon after I changed a bad alternator and battery a few months ago. At first, it would take 3-4 tries to get it started, and only happened about 25% of the time. But now, I can hardly ever get the car to start.

Before the battery/alternator change, a less frequent problem seemed to be with the starter motor or solenoid; I would hear a click of the solenoid dropping, but the engine wouldn’t turn over until the 3rd or 4th try.

Troubleshooting so far:
-Bypass the “clutch pressed” switch. No change.
-Replace the relay that was buzzing. No change.
-Bypass the relay. No change.
-Replace the starter motor/solenoid (during testing I noticed that tapping the solenoid would get a “buzzing” start attempt to work). No change after putting in the new part.

See the attached photo for the relay panel. The one that is buzzing is the one on the bottom row, furthest right (empty slot in this photo).

Problem relay goes in the empty slot on bottom right.

I’m not sure what to do from here. Any help appreciated.

 

Ignition switch. You can test the black/w wire on the ignition switch harness for power

 

@Seanjordan20 thank you for the suggestion. Would a bad ignition switch cause this "buzzing" behavior on the starter relay, though? I would think that a switch being bad would simply stop current from going to the relay at all.

 

Yes it would if it's an intermittent issue. When it buzzes you could be looking at a bad relay or switch. You switched out the relay which only leaves the switch. You can test voltage going to the relay by doing a voltage test on the wire I indicated above. The path of power goes from battery to 100 amp (under hood) fuse to 50 amp fuse (under hood) to ignition switch to relay to starter.

 

Maybe the contacts inside the ignition switch have become burned or corroded. That would cause bad connection & could explain the buzzing.
(BTW I changed the thread title)

 

That makes sense; I understand how that corroded contacts could cause that to happen.

Thank you for changing the thread, by the way! I wasn't sure how to do that (or even if I could... maybe that's a "super moderator" privilege )

 

Thanks for the detail on the connection of battery, fuses, and relays. I have a wiring diagram somewhere, but it was clearly incomplete since I didn't have that info.