HELP - Fuse Tap Connection

[mazinger]

I tested the front, center and the empty fuse slots with the multi-meter today. It was surprised that all the fuses are “hot” (active) without starting the car. In other words, there must be a relay or something between the fuse and the 12v socket to turn off the power to the 12v socket.

 

[Leonauto]

Did you take out the fuses when you were measuring?
Until you pull out - you can not determine which of the two contacts in the fuse block is powered (this contact is "hot")

 

[mazinger]

No, I did not pull out the fuses.

Why do I need to determine the hot pole? Does it matter?

I put the fuse tap in the fuse slot in different direction before and the power still hot.

 

[Leonauto]

No, I did not pull out the fuses.

Why do I need to determine the hot pole? Does it matter?

I put the fuse tap in the fuse slot in different direction before and the power still hot.

In this case, the direction of the current to supply the auxiliary device passes through the lower fuse. This creates an additional load on the main (lower) fuse, and in the case of a lower fuse, it will disconnect all

Spoiler

BUT.. only if the fuse tap is placed as shown and the left side (shown above) is on the "hot" side of the fuse bank. Turn the fuse tap 180 degrees and you will need the lower fuse installed. The subject of much discussion.. as to which way it "should" go. I am in the camp of as displayed the left side is on the hot side and you do not need the bottom (original) fuse to get power to the top (additional) fuse.

PS: You can check this: remove the lower fuse and check when the power is supplied to the drain cable

 

[Canuck(03)]

I own a 2016 Mdx and installed a Street Guardian SG9665GC, after extensive testing I connected my fuse tap to the empty fuse holder #22 which is ignition switched and only supplies power when the truck is running. All three acc power socket fuses are alive all the time and the sockets switched using relays ( located at the bottom of the fuse panel ) and you cannot use your fuse tap on these circuits. Fuse socket #22 only has one terminal located on the left side of the socket but this terminal is hot only when ignition is on, be careful to place the fuse tap so that the wire is facing away from the hot terminal and the fuse placed in the outside slot nearest the wire with the other slot empty.

 

[mazinger]

I own a 2016 Mdx and installed a Street Guardian SG9665GC, after extensive testing I connected my fuse tap to the empty fuse holder #22 which is ignition switched and only supplies power when the truck is running. All three acc power socket fuses are alive all the time and switched using relays ( located at the bottom of the fuse panel ) and you cannot use your fuse tap on these circuits. Fuse socket #22 only has one terminal located on the left side of the socket but this terminal is hot when ignition is on, be careful to place the fuse tap so that the wire is facing away from the hot terminal.

Thanks.

I just tried using the empty fuse slot #22 and #23. Both of them got “hot as start” when the ignition started.

Thanks again.

 

[Stubbs2468]

Had the same issue this evening on my 2024 Acura MDX. I learned a couple things.
1) use the driver side fuse box. In my tech package, fuse 42 was empty and turns on/off with the ignition.
2) fuses on the passenger side are powered all the time, yet the devices they power can turn off with the ignition, suggesting the power to them is controlled after the fuse.
3) fuse taps need both fuse locations filled to power the tapped device.

 

[Ralph2]

Had the same issue this evening on my 2024 Acura MDX. I learned a couple things.
1) use the driver side fuse box. In my tech package, fuse 42 was empty and turns on/off with the ignition.
2) fuses on the passenger side are powered all the time, yet the devices they power can turn off with the ignition, suggesting the power to them is controlled after the fuse.
3) fuse taps need both fuse locations filled to power the tapped device.

With #3 I think you have the fuse tap in the wrong way around, your way works but there is a ton of discussion on which orientation is correct.

 

[el-guapin]

.........
3) fuse taps need both fuse locations filled to power the tapped device.

No. you can use an empty slot and still power the additional device. As long as the empty slot is powered.

 

[Stubbs2468]

With #3 I think you have the fuse tap in the wrong way around, your way works but there is a ton of discussion on which orientation is correct.

I considered this. used a multimeter to check continuity, and tested it both ways. The only way for it to get power was to fill both slots. I suppose something could be wrong with the fuse tap itself. But there was continuity from 1 slot only.

 

[Stubbs2468]

No. you can use an empty slot and still power the additional device. As long as the empty slot is powered.

I considered this. used a multimeter to check continuity, and tested it both ways. The only way for it to get power was to fill both slots. I suppose something could be wrong with the fuse tap itself. But there was continuity from 1 slot only.

 

[el-guapin]

I considered this. used a multimeter to check continuity, and tested it both ways. The only way for it to get power was to fill both slots. I suppose something could be wrong with the fuse tap itself. But there was continuity from 1 slot only.

Check for 12v (not continuity) on the contacts at both sides of the slot. only on side should have power. Check with ignition on /off to determine if the power is constant or switched.
Constant & Ignition Power On Empty Fuse Slots

 

[Ralph2]

See how the current flows in the attached picture, depending on which leg get the current the flow will feed one or both fuses, passing the current on. There is continuing discussion which ways is correct. As shown power feeds both fuses, if it is rotated 180 degrees all the current must go through the first fuse to power the second one. So, if this was an empty unused slot one way requires two fuses and the other (as shown) will work with only a fuse in the second position

 

[NARider]

3) fuse taps need both fuse locations filled to power the tapped device.

A detailed explanation of the two possible orientations of the fuse tap (which I called Add-A-Fuse) was provided in response to my post about my dash cam installation. As is mentioned in both places, this has been a topic of significant discussion.