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Discussion Starter · #1 ·
Hi all, have a 2003 Sonata with a 2.7. Fuse slot #10 is a 15amp ECU fuse and it keeps blowing as soon as your turn the key on. If you unplug the ECU relay behind the dash and turn the key on, the fuse doesn’t blow. The fuse is getting GROUND on one side of the prongs and nothing on the other, when you turn the key on the side that was getting nothing now gets power and blows the fuse because it’s connecting power to ground. All other fuses are good including the other ECU fuses. Unplugged every fuse one at a time while testing to see if ground was still present at the ECU fuse prong with the fuse out and with every fuse pulled, nothing changed. Switched relays with a known good and same thing. Disconnected alternator, coils, CPS, o2 sensors, and injectors all individually and it does the same thing so I’m assuming those are all good. Since it’s blowing instantly and ground is present at the fuse, I’m thinking it’s a chaffed wire or an internally shorted ECU? I did a brief check of wiring but it’s late so I’ll check some more tomorrow. Does anyone have a pinout of the ECU so I can see if there’s signal going in and not coming out or coming out as ground? And any suggestions would be wonderful I’m no expert here, just a guy trying to fix his car. Thanks all!
 

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Discussion Starter · #4 ·
Take a look at the wiring at the crank position sensor....

It's on the front of the engine, just above the starter motor....
View attachment 461649

If I helped you fix it, why not...

Your support is greatly appreciated
Looked at the CPS and everything was good. Good power and ground, wires looked good themselves. Also unplugged it and it still gets ground at the fuse prong which should eliminate the sensor itself
 

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Here is the power distribution diagram for fuse 10 on the engine bay fusebox...
461671


If I helped you fix it, why not...

Your support is greatly appreciated
 
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