The ignition fuse keeps blowing, why?

Here's my trick so you can power up the circuit without blowing a lot of fuses. Replace the fuse with a small light bulb as per my drawings below. When the circuit is powered up and the short is present, the bulb will limit current to a safe value. If you use a common 3157 brake light bulb, that's one amp.

Now, when the short is present, the bulb will be full brightness. It gets hot too, so be careful what it's laying against. Unplug things and move wiring harnesses around. If you do something that makes the short go way, the bulb will go out or get dim.

The terminals are just generic universal crimp-type spade terminals. They usually come in a box of way more than you need. A friendly mechanic is likely to have a few extra in his toolbox he might give you. They usually have little insulating sleeves that can be twisted off if necessary. The clip leads I drew make the job of connecting the bulb easier than when using just pieces of wire. Those jumper wires can be found at Harbor Freight Tools for around $4.00 for ten.

Let me know if this makes sense or If I can explain something better.