2nd Gen Wiring Overhaul - A slow descent into madness

Good, there’s a lot of CCA advertised and often the ads are a bit ambiguous so if you don’t know what CCA is you would end up with it thinking it was pure copper. Nice thread.

 

Headlight Services harness and some recommended bulbs (a la The ultimate headlight upgrade thread ) installed and routed relatively neatly.

Of note: I spoke to the proprietor at Headlight Services about the 5/16 inch ring terminals that come standard. If you want a different size (like say to go onto military style battery terminals), or bare ends (if you're going full custom), send an e-mail before you place the order and let him know, he is happy to accommodate as each harness is hand made.

I've got the relays mounted to the driver's side fender, with the negative and the headlight runs running around the factory fusebox and under the radiator cowl:

 

Headlight upgrade is probably one of my favorite all time mods.

 

Yeah, it's neither difficult nor expensive and the functional benefits are immediate and objective. Hard to beat it, honestly.

 

nice work OP! This always seems like such a daunting task to me. I would love to do it one of these days though. My wiring is a bit corroded and could use replacing.

 

I feel it's one of those projects that makes itself seem bigger than it really is until you've done it once. I could do the whole thing again in a quarter of the time if you don't count paint drying.

There's also not really anything big to break or hard to fix if you hose something up, as long as you don't do something amazing like break a fastener off in your alternator or something.

 

As a note for posterity, this modification paid for itself recently.

My battery (a 3 year old Duralast Gold size 27F) blew its guts in BFE (!!!) and puked a fair amount of acid all over itself and the terminals thru the vents.

The corrosion happened so severely and so quickly (over the course of less than 2 days) that if I had still had the factory terminal with the open crimp and stamped ring, it would have meant replacing the whole Y-harness anyway, even if I could have gotten it clean enough to get a usable connection.

The lead (as in Pb) heads didn't corrode at all, which meant they didn't end up fusing together in a huge mess with the lugs on the cables/wires, and I was able to separate everything out to clean it up in the field with a scraper and a wire brush. That meant I could get the beast started with my jump pack through two fuel stops to the nearest getting spot for a new battery.

Some time in the next couple of days I just need to replace the two through-bolts out of anal-retentiveness, and replenish the dielectric grease on the terminals, but other than that everything is A-OK.

 

Pictures?

 

Of the carnage? Sorry, not really - I was pretty focused on getting rolling. I can take some pics of the corrosion on the hold-down and the corroded bolt in the terminal before I re-paint/replace, but there's not much else left to see!

 

@deanosaurus -
Do you recall what size ring terminals everything needed? 3/8? 5/16?

I'm trying to better understand what you did with the "2C" wire.

In your original photo of the wire harness, you have the battery connecting to the alternator....is this incorrect based on your revised "2C" wiring?

In other words. Should the Blue circled terminal below connect to the fuse box where I have the blue circle (photo 2)? And the red circle (that you have on the battery terminal in photo 1) actually connect where the red circle is in photo 3 (instead of the battery)?




And then the Red circle

 

I really should re-take these pictures, but I really don't want to gut the truck again until I have to.

Short answer: Your pictures and color coded circles are correct.

Long answer: please bear with me while I explain.

Let's reference this picture here:


The one labeled Alternator + is shown connected to the positive battery terminal. This is INCORRECT. Do not attach it to the battery terminal. Instead, attach it to the threaded stud inside the top of the fusebox (AKA 2E in Toyota reference material). This is where the factory alternator connection is. The factory alternator connection runs through a 130A (or 100A if you don't have the tow package/tow alternator) fuse, and then goes to the battery via 2C.

In order to attach Alternator + to location 2E, you'll want to bend the lug 90 degrees. I stuck it in a bench vice and used just a little muscle to bend it after it was already soldered and crimped to the wire, then opened it up just a HAIR with a small round file. It slipped into place no problem.

The wire labeled Fusebox + (AKA 2C), has one end connected to the positive battery terminal, and the other end you circled in blue goes to the location in the fusebox I showed you how to access with all the clips, where you have to remove the 10mm bolt and bend the little tabs.

The end you have circled is the one that can be a 5/16 in order to not have to mess with a washer for a good fit. You can just as easily use 3/8 for everything to save parts ordering hassle, just use a small thin washer to help it fit underneath the stock bolt, which is what I did.

For reference of the locations referenced above (2E, 2C) here is an abridged diagram:



Does all that make sense?

 

Perfect! That confirms everything I was thinking and makes it super clear for other users to reference. Thanks!

 

So:
1x 4ga 5/16" lug
3x 4ga 3/8" lug
6x 1/0 3/8" lug - one bent 90*

 

Yes, that is correct.

 

I'm afraid to even begin pricing this out given the rise of material costs lately!
But yes, I want this done for sure. Though I may need to measure alternator cables since I'm sure it's in a different location on my 2.7 engine

 

If I knew I at least had the lugs on hand (I have a crimper and solder setup) I'd just buy the cable and get it done. I've also got a fair amount of shrink tube, but no marine-grade with the glue inside, which I'd like to use for this application.
Maybe once I get all my junk unpacked from the move, I'll discover I have lugs.....likely not lol.

 

I'm right at ~$95 before shipping with extreme copper cables, battery terminals w/ boots, boots for the other 3 ends, and adhesive shrink tube. Using your setup's lengths.

 

Just to answer a few questions and remark on some things I forgot to say about the Big 3 install -

1) The body ground off the terminals in my implementation is much longer than it probably HAS to be, but what I found was that the extra length didn't cost much and made it MUCH easier to route the wiring, especially after I had to move to a different ground point on the fender because the factory bolt broke off. It also gives me plenty of slack to move the terminals waaaaaaay out of the way when I'm rooting in the engine bay, and provides room for people with additional stuff under the hood like aux panels or whatever to snake wherever they might need to snake with it.

2) You could use smaller than 3/8" lugs on some of the ends if you wanted to get absolute maximum metal to metal contact on e.g. the alternator and starter studs. This is not disputable and I believe @JohnnyRed actually figured out the electrically optimal (i.e. largest surface contact) lug sizes for each end of each cable. That being said, when I did the math for actual additional surface area of a 5/16" opening vs a 3/8" opening, when accounting for the full contact area (body of alt/start plus inside face of nut/bolt) the practical difference was not sufficient in my opinion to warrant the additional expense of ordering multiple sizes (a 50pack is FAR cheaper per unit than a 10pack is FAR cheaper than a 5pack and so forth).

3) Getting the factory harness with all the little *#$Q^#% clips apart is crap. Getting into the fusebox for the first time is similarly clip-studded crap. When I have a minute, I'm going to see about making a quick video clip about gutting the fusebox.

 

First off, this isn't an argument or a critique and instead more of a thought or preference here. Admittedly, I haven't done the math (if you have some numbers to share, I'd love to see it).

That said, personally, I'd probably opt for the smaller rather than the larger lugs. (Again, maybe you have math to prove this is a bad idea?) I assume that since these connections are so solid and short distance (effectively zero) that you don't need a ton of surface area to flow what's needed. In the past when I've built ground and charge harnesses for other cars one of the thorns in my side was lugs that were too damn big for the factory connection points. Which meant grinding, cutting or modifying - which I'd prefer not to do as a principal but it's also extra work and sometimes quite challenging. For me I'd always be looking to use the smallest lug possible. I've even drilled out smaller lugs to fit over larger posts/terminals for tight fitments. Most of the times when we build this stuff it's way overbuilt and over capacity of what we need anyway so if I lose a small % of capacity due to a smaller lug then that's a trade off I'm willing to make and likely something I never needed in the first place.

 

I appreciate the disclaimer and I also greatly appreciate reasoned discussion. I don't have the math to hand but when I get back to my office I'll show my reasoning and numbers.

From memory, the contact surface area for a 3/8" vs 5/16" opening on the alt/starter lugs is different only by something very close to (0.25")^2, or twice the difference between the area of a circle with r=6/32" and a circle with r=5/32" (big hole minus little hole, times both sides). Compared to the surface area of the attachment points on the alt/starter bodies plus the surface area of the nut/stud securing them, this is a very small bite out of a very large margin.

This is my reasoning as well. There is more than ample surface area to transmit the power we are working with even if the lug openings were significantly larger (and contact area therefore smaller).

Yes! It is always frustrating when there's no space left in the design for the physical connection, haha! In real life, wires aren't magic one dimensional lines, something which sometimes gets overlooked in the design package. Thankfully in this application, the overall size difference (not the opening size, the max dimensions of the lugs) is not a factor, there is far more than enough room to fit. In fact, the overall size of 0awg lugs regardless of opening size is more or less the same. Now that I consider it, I believe I have even seen "blank" lugs that could be drilled for a specific opening size for a special application.