Hey guys, new to forum but not new to cars (kind of)

I work on audi (no hate please haha!) and have done so for about two years.. Anyway, recently my brother donated a 1998 volvo s70 t5 to me... apparently he thought he knew how to change a battery, and reversed the polarity... The car has 200,000 miles on it so he didn't even see worth it to fix it. Being a car person myself, I figured why not give it a shot. I have a good mechanical background but electrically I always stumble.

Here's what I know so far
- the battery was hooked up backwards
- when ignition is on and a NEW battery installed the time and things appear in the cluster but no lights (check engine etc)
- after checking fuses I find the ignition switch fuse (fuse 10 I think, 15amp) blown. every time the key is turned to 15 power (ignition on) the fuse blows
- I pulled the main fuse box open and removed all the 50 and 60 amp fuses (big red and yellows) and tried to isolate a circuit to go further into.... I plugged them in one by one (with a fresh ignition switch fuse, and ignition on) until I saw the 15amp pop. It appears to be the 60amp 3rd fuse down from the top, yellow "power to fuse panel, aliment boitier fusib" (as it says on the cover of the main fuse panel - obviously sometimes those legends aren't correct, at least with Audi) main fuse that makes it pop...


Here is where I don't know how to continue, I am familiar with audi wiring diagrams and that would be my next step, but I looked up Volvo wiring diagrams and was LOST, totally different game.

Any input on what that fuse is powering, where to look for a short, or overall any input on moving forward? I am thinking maybe the starter or ignition switch were fried, but don't want to shotgun parts

I know I just typed a book but I was trying to cram as much information as I could (as disorganized as it is) to avoid questions that I already had the answer to...

Thank you so much in advance!

 

Generally speaking, solid state stuff doesn't like reverse polarity. Things like mechanical switches usually don't get damaged by that. The 60A fuse is the wrong direction. 15A is going to be something smaller. Unplug things like the radio, whatever other electronic devices you find. Then plug stuff back in until the fuse pops.

 

Thanks for the info! I see you say unplug things like the radio, but if the 15 amp fuse is "ignition switch" wouldn't it likely be something ignition related that is blown? Again, my experience with volvo is limited, do they group random things like radio into fuses like ignition switch?

 

Fuses blow from the upstream side. Determining a blown fuse from a revered battery is just a hunt an dpeck project. You may be better off disconnecting the battery, replacing the blown fuse and use a VOM to test ohms to gorund. It will take time but you will eventually find it