Trying to wire up an auto-dim rear-view mirror retrofit via add a circuit (2002 R53 not pre-wired for auto-dim mirrors) and I observed some odd behavior when trying to get power to the mirror.

So I have a 10-amp (max) add-a-circuit, which I plugged into F9 (instruments) - this is a 5-amp fuse that I assumed would only be powered when the key is in the ignition.

Doing this resulted in the mirror working while the key as out of the ignition and the mirror not working while the car was turned on.... can anyone explain this behavior?

I also have a couple of other questions related to this problem...

1) The add-a-circuit is only rated to 10amp, but the mirror specifies 20amp, has anyone added a higher ampere fuse to a lower-rated add a circuit?

2) Will the mirror work correctly from a 10amp fuse? or should it go to a 20amp? The mirror doesn't seem to work when hooked up to 5amp fuses.

Help is very much appreciated!

 

Make sure you are plugged into the "hot" pre-fuse part of the fuse block...
Adding a fuse to the side of the fuseblock AFTER the fuse will result the orgionals items fuse that you piggy back on limiting the amps, and just acting like a tap/split with an extra fuse....
No experience with the items you are installing....but 20 amps is pretty BIG fuse...and a heavy wire...wonder if the paperwork lists a 20 amp fuse cause it shares the fuse with other items....did it blow the fuse?
Remember.... THE guage of the wire you used in the install limits your fuse choices.....

 

Thanks Zippy - appreciate the reply.

My bad on the correct amp-rating for the circuit. It's actually a 5amp fuse (fuse F35 is for the mirror,also for the outside mirrors).

Used 16 gauge wire (I think) - was thicker than the original wiring to the connector anyway. Solid copper not stranded (shouldn't make a diff?)

Which is the hot part of the fuse block? Fuses on the left side? Or am I misunderstanding?

 

Should point out that I'm using the type of add-a-circuit labeled as BP/HHA here: http://www.escortradarforum.com/foru...ead.php?t=8274 (has two slots for regular ato fuses), rather than just slotting over a single fuse blade - maybe that's what you meant by hot side?

 

By the "hot" side, I mean the part Thst stays hot when the fuse blows...just take a test light or multimeter to the fuse slot (guess you could put a blown fuse in the slot... If the add a fuse is hot, you have the right side...if the add a fuse is dead...plug it into the other side).
Generally stranded wire IS ALWAYS used in moving vehicles or anywhere vibration is present....a solid wire will fatigue from movement or vibration... And thus fail... And make a hot spot at the bend that is a fire hazard (you would be protected by the fuse if correctly sized).

 

The AAC needs to be installed upside down. If it's rightside up (you can see the fuse rating) you're running unfused.