I generally do not like using add-a-circuit fusebox taps because there is some chance that the add-a-circuit device could fall out of the fuse box taking with it both the OEM circuit and the added circuit inasmuch as the add-a-circuit device is plugged into a fusebox in lieu of fuse protecting the OEM circuit and when installed would contain fuses for both the OEM circuit and the added circuit. So my preference would be to tap into the fusebox by plugging the add-a-circuit device into one of the unused fuse slots. Based upon my probing there are a number of such fuse slots available in the constant on condition (there may be acc-on available slots too, I have not tested for those yet). So my question: Are there any issues involved with taping into one of the unused fuse slots?




One possible issue (at least theoretically) is that even though the add-a-circuit device would be fused for the additional circuit being added is that that added circuit could overload the "feeder" circuit or upstream circuit potentially blowing the upstream circuit overload protection device (a fuse most probably) thus knocking out all the sub-circuits associated with that upstream circuit (this is a risk however of using the add-a-circuit device with a either a used or unused fuse slot that's why it's always a safer bet to go directly to the + terminal of the battery when adding a circuit, especially a higher load circuit). So my second question, designed to allow me to minimize a potential overload situation (or an overload of critical circuits) by picking a fuse circuit least likely to overload: is there a schematic of the under-dash fuse box available that shows the upstream circuits (and their associated fuses) feeding the individual fuse slots?




Hope my questions have been clear.

 

All this information is available in the Honda Fit "Electrical Troubleshooting" manuals (not part of the three volume shop manual set). Just purchased a new manual off eBay for $16. Has schematics for EVERYTHING in car. Don't leave home without it.