Accessory power at the trunk outlet

yugrus

Contributor
:
CX-5 GT
I can't be alone in my wish to have rear outlet to only have power only with ignition on. We take a portable 12V cooler with us on the long trips, and it is a pain to run out to the trunk to turn it off at the gas station. Small battery can't sustain that power draw for long, so I do it every time.
The front in-dash outlet has switched power, and here's my attempt to provide that to the rear outlet.

Here's what I used:
- ATT- type add-a-circuit tap
- ATM- type fuse extension. I couldn't find ATT-type extension, but ATM will do no problem.
attachment.php


Cut off ATM prong portion:
attachment.php


Then solder add-a-circuit tap's external wire to one of the wires from the prong. You're not going to connect the other wire to anything, insulate it and leave alone:
attachment.php


Here's how mine looks like after wrapping it. Insert two 15A or 15 and 10A fuses in the tap.
attachment.php


At the car, inside the cabin, open the fuse box cover by your left foot. Here's what you're looking at and for. 15A fuses, the upper is for the front outlet, the lower- for rear. Power is provided to the outer prong of each fuse- right prong for the upper, left prong for the rear.
attachment.php


Take out both fuses. Insert your contraption in there the following way:
Add-a-circuit goes to the upper fuse slot. The wire should be facing left. ATM prong goes into the lower fuse slot. The prong that is connected to the tap wire should be on the right side. The way that the taps are inserted is VERY important:
attachment.php



Now check both outlets for the power while ignition is off and on. Open a cold one and congratulate yourself!

Do not try to run full load on both outlets at the same time. The circuit is protected by 30A fuse upstream, with many more loads on it.
 
That is a very nice way to do the job. No permanent mods to the car at all. Everything hidden. I like it.
 
Thank you! For a cleaner set-up the relay should have been used. Although the standard automotive relay doesn't fit in that compartment. As long as you know not to run a cooler in the back and a coffeemaker up front, the load balance will be fine.
 
I get why you want this except for the gas station part. If you're only gassing up in 5 minutes or so, why do you turn it off in the situation? Nice mod though. [emoji106]
 
I get why you want this except for the gas station part. If you're only gassing up in 5 minutes or so, why do you turn it off in the situation? Nice mod though. [emoji106]
Sometimes it takes more than 5min to take gas and take a leak :)

You'd be surprised how fast the battery can run out of juice, particularly the older one. Ours is top notch with smart charger hooked up weekly for two days or so. That's the routine I follow with both our cars.
Years ago I managed to completely drain the battery in my then- Envoy after having a quick bite by it's side in the middle of nowhere. Our cooler takes 5A, the lunch took about 20 minutes. Good thing I had booster...
 
You'd be surprised how fast the battery can run out of juice, particularly the older one.

How seldom do you drive your cars that you need to hook them to a charger that often?

Nice mod!
 
Tahoe- not that much anymore. Masda more frequently. But even if they were driven every day to work, the battery state of charge would not be near 100% no matter what. Batteries love to be at 100% though, otherwise they last 3-5 years, even less. It doesn't take much for me to hook Mazda up- the quick connect is right under the rear hood edge, by the wipers. It's a garage queen, so the charger is on the wall right by it. I don't have to open the hood to hook it up. The charger is controlled by WiFi switch/timer.
Tahoe got marine smart charger under the hood, besides other interesting things. It has the waterproof marine power outlet attached under the rear bumper. So when I back into the driveway, it's easy to hook up the extension cord right away. I literally have to trip over it when I get back into the car, so no chance I'd forget to unhook.
The household power to the car and few other things are also controlled by WiFi switches/timers.
 
Last edited:
I actually wanted the trunk outlet power on demand, not on ignition.
Therefore, I installed a switch instead.
1636173091858.png

1. Use a fuse extender and plug into R.OUTLET3 (Fuse #3 15A); I used 10A fuse instead of factory 15A because the switch is rated for 15A and I wanted to be safe and keep current under limit.

1636173292285.png

2. Cut one wire (of two wires) of the fuse extender. You will bridge a switch here. Don't connect it yet because you will need to install the switch into the panel first and the fuse extender is too big to pass through the hole.
1636173188247.png

3. Find a spot deep enough to accommodate switch and wire connectors. Drill a small starter hole into the driver side under panel. Be careful when drilling ABS. Drill bit bites and tugs if you don't use a variable speed drill and go real slow. Better yet, use a hand drill.
4. Progressively increase drill bit size. Once I hit 1/2" drill bit, I started to use a hand countersink reamer until it went through.
1636173241140.png

5. Use plumber's deburring tool to smooth out edges of hole and increase hole size. Careful not to make it too big. Keep check if the end of switch will pass through.
1636173362846.png

6. Determine whether you want to toggle up for on (left hand drive nations standard) or toggle down for on (right hand drive nations standard). You need to do this because there's a notch on the side of the switch that prevents it from rotating. You need to make this notch.
7. Use X-Acto knife to carefully cut a notch; 3 o'clock if toggle down for on or 9 o'clock if toggle up for on.
8. Before you push the switch through, connect wires to the switch long enough to reach fuse extender plugged into the kick panel fuse box.
9. Push the switch through and admire the near factory look.
10. Route wires to kick panel and bridge the cut wire of the fuse extender.

Now, you can use the switch to turn the trunk power On or Off.
 

Attachments

  • 1636173177320.png
    1636173177320.png
    126.9 KB · Views: 53
Back