BMWBig6

Does this mean there is a problem with the original accessory or circuit (which uses the lower Fuse Slot A)? Or could the problem still be with the new accessory or wiring that I added (upper Fuse Slot B)?

The original/host fuse is 5A, the new accessory fuse is 10A. It's the 5A one that keeps blowing (immediately when I turn on the power/ignition). The 10A fuse is fine. Does this mean the cause is a draw greather than 5A, but less than 10A? (Or does the Add-a-Circuit always cease working once the lower host fuse blows?)

The weird thing is that this setup has worked fine since June. All of a sudden the 5A fuse blew today and replacing the fuse doesn't fix it so I need to know where to start troubleshooting. Thanks in advance!

mike d

I'm no expert so, you know...
I guess there is a possibility it is the fuse tap itself, but if it was working fine, and it just started blowing the 5A, then it is probably whatever it is connected to. As a test you could disconnect the fuse tap, and the amp, and stick a 5A fuse in without the fuse tap to see if it still blows. If it doesn't, I'd buy a new fuse tap.

SpeedViktm

Yeah, get the add-a-circuit out of the mix and see what happens.

I'm not overly familiar with the wiring inside of an add-a-circuit, whether it's parallel or serial. When the 5A fuse blows, does the device on the 10A also quit working? Sounds like a yes, so that would tell me it works serially. To me, it sounds like a bad idea to have the add-a-circuit on a fuse that has a lower rating than the added device might draw.

BMWBig6

Yes, when the 5A (original) fuse blows, the new accessory (on the intact 10A fuse) stops working. I forgot to mention this important fact.

BMWBig6

It's definitely the new accessory. I reversed the polarity/orientation of the add-a- circuit to the correct way, and the host fuse survives and the new accessory fuse blows. All the connections appear fine so I will need to trace the whole wire. Could it be an internal failure of the accessory too?

mike d

Most definitely. If you can trace the wires (power and ground), and you can't find anything, then it's probably something internal to the accessory.

BMWBig6

Thanks! I rewired everything (but re-used the accessory's pigtail wires and spade connectors), and even after taking power straight off the battery and using a different ground, it blew the in-line fuse every time as soon as contact was made. Does this point to the accessory itself as the problem (internal short, etc.)?

SpeedViktm

Sounds that way.