I need to run Ignition On power to three more places. Because I don't want to cause problems, I bought a 3-fuse fuse block that is Ignition On hot. I plan on running a fuse tap to the supplied relay and that will give me my three locations.

The only potential issue I see is, one of the spots i need the Ignition On hot is for my new wiring harness & ECM. The harness came with a built-in fuse block including one that is for the Ignition On wire. So, if I wire this to my new fuse block it'll have two fuses in it. I know it's not ideal, just wondering if it'll cause any problems? And, should both fuses be the same amperage or should I make one a little higher (i.e. 10 amp & 15 amp) so that I pretty much know which one to look for in the event of a problem?

 

Make them both the same.. Idealy only one is needed though

 

That is how the harness is designed , gives you separate fused protection on each of those three harness circuits down stream from the main (Ign ) fuse in the car
Also simplifies fault finding because if one of the three systems is not working ( and the other two are ), you know that fuse is blown, not your main Ign fuse
Harness should have came with correct size fuses for each of the three circuits