There are few more disheartening moments for an automotive enthusiast than that moment you turn the key and nothing happens. No clicking. No start then stall. Just dead silence. A few days ago I had one of those moments.
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| Not a good sign when you’ve turned the key. |
In this week’s post I’ll go through the process of upgrading the old wire harness with new custom heavy duty wires and why I went that route rather than an replacement OEM harness.
Before we get started, I’m going to be nice and give you a heads up as to what you’ll need for this project:
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| New HD cables with military style terminals New 770 CCA Group 34/78 battery |
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| Ratchet with short and long extensions 10mm shallow socket 13mm shallow & deep sockets 15mm shallow & deep sockets |
In addition to the above pictured sockets, I used a few zip-ties to bundle the new wires together along with a pair of snips to trim the OEM fuse box (see picture bellow).
First things first, why spend the money for custom heavy duty cables:
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| 11year old OEM battery cables Exposed and corroded wires Beat up lead terminals |
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| Ground was just as bad most likely caused the battery to drain to 0% |
As you can see from the above photos the 11 year old OEM battery cables on my Jeep were toast. The wires were exposed allowing moisture to corrode the copper turning it a nasty green color. I had the exact same thing happen on my ’97 Grand Cherokee and had to cut back more than 12″ of corroded wire before I could find clean copper to splice a new ground terminal to. This time around I figured I’d just replace all the wires right from the get-go.
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| Military style battery terminals allow for better flexibility when wiring accessories and for future repairs |
I also opted for military style battery terminals to make wiring accessories a little easier and also make replacing an individual wire a little easier. I chose this option mainly because in an overlanding scenario it’s much easier to work with crimped on terminals (pictured bellow) rather than the OEM cast-lead style terminals (pictured above).
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| Well made, well labeled, cables Ends are heat-shinked with properly sides terminals |
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| Alternator lead has fusible link already spliced in. |
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| Not only are the cables labeled, but the battery ends are wire-tired together This helps with routing the new wires which are loose and not in an OEM type “harness.” |
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| Wire Porn! Bad grounds frustrate me so much. So glad to have quality cables now. |
If you’ve ever worked on vehicle electrical systems you know how frustrating bad grounds can be. With heavy gauge wire, quality terminals, and water resistant shrink-wrapping this cables are hands-over-fists better than the OEM cables or off-the-shelf parts store cables.
Now… let’s start on the install part. Well, rather let’s start with the removal of the OEM battery harness. Once the battery is disconnected and removed, I started with the ground wires:
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| One ground wire attaches to the block (13mm) |
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| The other ground wire attaches to the body (15mm) |
Once the two grounds were disconnected I removed the power wire attached to the starter (13mm). Here is a comparison of the starter end of the OEM harness verse the new custom wire. You’ll also notice the new wire comes with a boot! This is a nice upgrade given how low the starter hangs. This will help keep the terminal clean of dirt and mud.
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| Starter end of the new wire (left) compared to the 11 year old OEM wire (right) Major bonus points for the new wire: better terminal, heat shrink, and a boot! |
Once the starter end was disconnected I moved to the alternator and the fuse box.
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| Be very careful with these. It’s very easy to snap the plastic housing. A conservative amount of PB-Blaster should be carefully applied. Also refrain from using an extension. Soft gentle pressure is your friend. (10mm) |
The fuse box is two bolts for one terminal that has two wires coming to it. One is from the battery the other is the fusible link from the alternator.
With everything disconnected it’s time to perform your best impression of H.P. Lovecraft and call forth Cthulhu as you snake the tangled mess of the OEM battery harness free of the engine bay.
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| Out with the old… Time for the new. |
Installation is pretty much the reverse of the removal. Since the new wires are not loomed or bundled in any kind of harness it’s both easier and harder to put them back in. I just followed my previous steps in revers. I did the grounds first, then the starter, then the alternator and fuse box.
The new wires were a bit of a tight fit inside the fuse box and I found I had to do a little trimming to get them to fit. First I had to trim a little off the terminals to get them to lie flat side-by-side on the fusebox studs. I also had to trim a small bit of plastic from each side of the opening to clear the new heavier gauge wires.
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| Minor trimming to both the terminals and the fuse box opening. |
A word to the wise. Electrical connections do NOT need to be super tight. If you over tighten them you risk irreparable damage to things like the starter, fuse box, batter, alternator, and even the body. Once the nut or bolt has made contact snug it down with light pressure. You don’t need to torque it down super tight.
With all the new wires in, it was time for the battery. Once the battery was in I was able to tease the tires and bundle them together with a few zip-ties. The zip-ties helped the wires work together to support each other and lift them up and free of any entanglements. I will say a minor downside to the custom wires is the lack of ties and wire loom. As of right now the wires do rub on the fender well, oil filter, and a/c refrigerant tank (at least I think that’s what it’s called). At some point soon I find some appropriate wire loom. Not only will this protect the wires but it will dress them up to an OEM appearance.
A bad set of battery cables and chassis grounds can be frustrating. They can cause a host of electrical gremlins as well as trickle-drain a batter. Once a battery has been drained to 0% it’s pretty much worthless. I tried jumping my battery as well as putting it on a trickle-charger and both failed to revive the battery.
In contrast, a low voltage battery (under 12 volts) can be revived. Usually it just needs a jump start (and then let the alternator do it’s thing) or a trickle charge. A mostly dead battery is still slightly alive:
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| It was either a ‘Princess Bride’ reference – or – Monty Python Quest for the Holy Grain’ ~ “I’m not dead yet!” |
Sadly my battery being at zero volts was stone-cold-dead and could not be revived by a trickle charger (usually they need at least 3 volts or so to start a charge). Other common causes of bad batteries are freezing (had it happen), vibrations that can cause a broken plate to cause an internal short (had it happen), or just age which diminishes the capacity of a batter to discharge and recharge (had that happen too). Most batteries will last the average person in an average car more than 5 years. With the abuse I put them through I’m lucky to get two or three years out of one (thank the maker for warranties).
On that subject, as far as batter replacement I honestly wanted to get an AGM battery due to their resilience off-road. Sadly this whole mess was unexpected and I had to settle for a traditional battery. Luckily with a 770 cold-cranking-amp rating this batter should serve me well for the time being.
For those that are curious… I got the new battery cables and military style terminals from CustomBatteryCables.com and the battery from Napa Auto Parts. I am neither affiliated nor sponsored by either company. I only chose them for their positive online reviews and by research I had conducted on various forums.
Anyway, hopefully this helps get you pointed in the right direction. I have a few more electrical upgrades planned for the LJ so stay turned for more on this topic later this fall.
