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Hey, all! I was recommended here by a friend because I have serious electrical gremlins running around in my engine. I was driving my 2007 Honda Civic Si down the road when the engine died suddenly with no warning about 100ft before I was about to make a turn. It's possible that it could have died a few seconds beforehand, but didn't shut off until I popped the clutch. I don't actually remember whether it died right when I popped the clutch or a few seconds after. I pulled over and tried to start the engine. It cranked, but it wouldn't start. It just cranked endlessly until I stopped holding the key. When I first insert the key and turn it to the ON position, but don't start the engine, the temperature gauge, which is to the left of my speedometer, and the fuel gauge, which is to the right of my speedometer, both play their starting animation of showing the maximum value, then trickling down to zero. However, once the gauges read zero, the fuel gauge then shows the correct value, but the temperature gauge completely disappears. That section of the dash to the left of the speedometer is completely black. I poked around my relays and found that no power was going to the fuel pump and I believe no power is going to the fuel pump relay or fuse. I swapped the fuel pump relay with an identical relay and got no change. I disconnected the battery for 15 minutes then reconnected it, but nothing changed. I eventually gave up and had it towed to my mechanic. When he connected his scan tool to my OBD2 port, the scan tool was unable to connect to the computer. Every single issue I have mentioned in this post appeared when the engine died. Does anybody have any ideas of what I should check with a multimeter or something else? Any help would be appreciated!

 
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Check fuses.

 
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Which fuses?

 
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All of them. There are only about 40 located across 2 fuse panels: one under the dash, and one in the engine bay.

Can you post a video of what the cranking sounds like?

 
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With a meter don't just eyeball them

 
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Ok, thanks! I’ll check them all with a multimeter and send a video of the sound of the cranking.

 
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Hey, all! My mechanic was able to figure out what happened.

I had incorrectly reinstalled the idler pulley after replacing it, so the serpentine belt was riding on the pulley one groove too far to the side. The edge of the serpentine belt rode along the edge of the idler pulley and was torn up until it started fraying. A string that was hanging off of the serpentine belt grabbed onto the wires for my crankshaft position sensor like a weedwhacker, tore the insulation off of them, and shorted power to ground, which fried my computer. Thankfully, he was able to reinsulate the wires and reprogram my computer. I cost myself ~$500 by screwing up one bolt. :’)

 
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Well damn! Glad you got it fixed.