yotaman85

After reading another post (that i can not find anymore) about replacing the power supply wire to the fuse box with good results, i decided to do the same after i noticed mine was kinda old and crusty. turned out its a good thing i did because the stock wire is puny already and had broken, only to have the PO splice it back together with even smaller wire.

After the install i am amazed at the HUGE difference i noticed in my electrical operation and would call this a must do. the exterior and interior lights are noticeably brighter. the radio sounds much better and the truck even seams to run better (more power to ignition and sensors maybe).. and yes the horn is also much louder. also noticed less voltage drop when rolling up more then one window at a time.

I really wish i had taken pictures and will probably go back out and take it apart to take some tomorrow. I will try to give you a step by step without the pictures.

NOTE: I own and performed this on a 4WD 2nd gen 4runner with a 3vze and an automatic transmission and am not sure on the other generation pickups or 4runners. but should be very similar.


I used 4gauge wire with pre-connected hole tabs on each end of a 14 inch cable. that is all i had to buy, but you may have to buy a positive terminal connection with an extra bolt or one that uses a clamp to hold the battery cable to the terminal.

make sure the first thing you do is disconnect the battery, both positive and negative, and remove the battery to give you some extra room.

unbolt the fuse box by removing the 2 10mm bolts that hold it on the passenger fender.

then take off top cover and flip the box over and remove the bottom cover.

remove the main fuse from the fuse box, it is held in with a clip system similar to most connections. it will come out by lightly prying on the clip and pushing it out of the bottom of the fuse box.

follow the stock wire to the side it mounts to on the fuse, the stock wire is crimped to a plate that spans across two connections on the side of the main (80 amp) fuse, the crimp that holds the stock wire to the plate needs to be cut off at the bottom of the plate to do the mod with the same gauge wire i used. then use the factory bolt that holds on the other wire above the main supply clamp you just cut off to bolt on the new cable.

then run the new cable to a mounting place on the positive battery connector.

install the main fuse back into the fuse box, reversing the removal steps.

run the new cable through the stock location on the bottom fuse box cover and install bottom cover. (NOTE: the new cable was applying a small amount of pressure on the bottom cover causing it to bulge slightly, but should not cause the bottom cover to come off.)

bolt the fuse box back into place and re-install the battery making sure all connections are tight and clear of other connections.

if you have questions feel free to ask.. should take about 20-30 min for an average weekend wrencher.

Good luck!

yotaman85

also, i feel i should add you do not have to use a 4gauge cable, a 6-8gauge would work also, obviously the bigger the better.. i will also be running heavy gauge grounds and will also post the install steps and results.

yotaman85

just noticed after driving around for a minute the heat inside the engine bay warmed up the cable and let it mold and contour to the shape of the box so the bottom cover does not bulge anymore..

rusche

That cable was a fusable link... which is why it appeared broken and frayed and smaller...

Philbert

iTrader: (2)

Good write up - do you mind taking some pics when you get a chance? I just replaced my battery cables, and noticed the wire (+) going to the bottom of the fuse box is old, small, and not OEM...I've tried to take it apart in the past but never got the bottom off (was worried i'd break something). Would love to see this with pics, broken down step by step

yotaman85

the cable goes into the fuse box and connects to a fuse, i doubt it has a fuse in line..

yotaman85

also, I doubt the wire was stock. it was maybe a 18gauge wire connected to a 16gauge wire via clamp. unless this is the "fusable link" you are talking about.. I will take pictures tomorrow and show you exactly what im dealing with. maybe more of a melt-able link.

Bridger5228

Uh ya. Fusible link going into a fuse....LOL. Not likely......

yotaman85

im kinda surprised at the difference, isn't the fuse box supposed to get its power from the alternator? then to the battery?

LITLRED

The alt, battery pos and fuse box are all connected together.
Nice write-up. For a few more $ you can add another 80 amp circuit for auxiliary power.
https://www.yotatech.com/forums/f116...p-fuse-207514/

yotaman85

thats a good link LITLRED, im taking pics now.. after driving to work and back, a 52 mile round trip, it has definitely made a difference in the way the truck runs. It holds O/D much better and did not have to down shift coming out of a wash i drive threw every day..
also, the ECT seems to actually make a difference when it is engaged, shifts are a couple hundred RPM higher and a little firmer (although i would like to see it make more of a change in shift pattern)..

yotaman85

here are a couple pics, batteries craped out on my camera...
seems to do this allot.

anyways, you can see the obvious size difference. I have wrapped it with red wire sheath to indicate positive..

and the multi-connection terminal that was on the truck already.

blue_CA_yota

I did this fix a few months ago, made a huge difference.. I first noticed the problem when my radio was cutting out when I hit the brakes.. then my truck was stalling when I put on the turn signal, head lights etc.. I found that thread you spoke of, and did the fix..

The different gauges and "repair" job..


Those 4 crusty wires were attempting to supply all the power.. They broke while I was trying to take the wire off the battery terminal..

Blue_petersen77

Nice, I have some wire I picked up off the job site and plan on doing this myself. So I'll probably come back to this write up.


I got an idea... Why don't you try a positive wire mod on your camera too? =)

good write-up man

yotaman85

haha, i think ill just stop buying crap batteries.. maybe i should get some lithiums for my camera like all my flashlights..

hilandfrog

I too was "playing" around my electrical system.....
Seems the "large" wire coming from the brass screw under the fuse box
connects w/ a smaller wire, on it it states fusible link ...???

I ended up putting a new ring on and calling it done :dunno

Repo

Blue_petersen77

Just finished up with this mod. I used the 6 guage wire.
The biggest PITA I had was getting the old wire out where it was pressed in and soldered. (I only had one wire end connector). If I had gotten 2 it would have been a sinch and only taken about five to ten minutes. Overall, from start to finish it wound up taking me 45 minutes.
I haven't gotten a chance to take her anywhere, but I didn't get great results so far. I tried the widows and radio etc. And can tell a minimal (almost imperceptible) gain but I'll have to see what happens when I take her out.

6 guage wire was $2.97 a foot you only need about 7 or 8 inches
wire connector was $.75 a piece. I'd definately suggest getting 2!

WILLTHISIFSGOHIGHER

bump im subscribing

milehigheric

Thats a good idea mate...keep playing with that electrical system and hope for the best. What is the worst that can happen right?

*sarcasm

Blue_petersen77

Update: well I gave it a week to see if I could tell any gains... One gain I had (for whatever reason) I have better hill hold. Some hills that I usually drive up the tranny always geared down no matter how played with the gas pedal but now I can get up and over most of the hills without kicking down or much play with the pedal.

Also, when I used to turn on the headlights or ac or crank the stereo everything would dim a bit.... Now it doesn't dim out at all even while rolling down the windows.

So I have seen good results and reasons why I would recommend this mod now.