2005 Corolla -cranks, no firing, blows fuse 15, 20

The morning after driving through many puddles in a major NYC rainstorm in October, my corolla cranked but there was no firing. My mechanic replaced fuse 15, but was not sure it was related to the rainstorm. Three weeks later, it happened again - no rainstorm. I replaced the fuse myself and it started. I made 3 stops and it happened again. This time, it continued to blow my box of 15 fuses. mechanic couldn't find problem and it starting working again spontaneously after replacing fuse 15. Drove it to Toyota dealer, found nothing $300 eval - replaced fuse 20 and 15 (in front of fuse box and different from original 15 replaced in middle of fuse box). They said to wait until it happens again! I've consulted with other mechanics who have suggested possible computer failure maybe due to rainstorm or possible wire corrosion/rodent corrosion. All agree that they have never heard of this happening with a corolla. I've had no problems with the car..has 103K miles. I need my car for daily home and school visits and can't wait until it happens again.

 

It is possible that a rodent ate thru your wires under the hood. It just happened to me and took out my brand new Tundra when a rodent ate thru the main engine harrness. to the tune of over 5 thousand dollar damage.
This is the time the critters look for warm spots and your Toyota engine fits the bill.
I would have a detailed inspection done of all your wires looking for chew marks and nesting material like leaves in your engine compartment.

 

It sounds like a mild overload. What amperage fuses are they?

There are free online services for auto schematics; see if you can find out what these fuses protect.

Also, if you can get the amperage you could install a resettable circuit breaker, to buy you time until you can fix it or until it disappears. A burnt-out fuse makes an ideal mating connector for this breaker.

 

I just wanted to add that this is the fuse box under the hood in front of the steering wheel. I was told that the ECM1 and ECM2 fuses were replaced. THe manual does not have a schematic diagram for this fuse box nor can I find it online for a 2005 Corolla so I don't know which circuitry they control...neither do the mechanics that assessed it at a Toyota dealer!! Everyone has been vague...Thanks to those of you who offered suggestions!

 

Dealers don't want to admit it, but they have Event Recorders that they can loan to people.
It can be triggered by the fuse blowing, and it reads back data from many test points on what the elec. system was doing just before the fault occurred.

I made a very simple one to trace down an intermittent problem with my Sentra refusing to crank.
The thing was, when I hooked up the unit to test it, the fault showed up immediately and so I was able to determine that it was the relay that disables cranking if the clutch pedal is not fully depressed.
Your problem is somewhat more difficult.