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JimT · 01-10-2020, **(Subject: Electrical wiring )**

So I've been working on rehabbing my tractors electrical system. Thanks to all the great information on this forum. Right now I have 2 specific questions.

1: On many of the wiring harnesses the plastic wire loom is starting to fall apart. Brittle, cracking, even crumbling. Is it a better investment of my time and money to replace all the protective loom or just bite the bullet and replace the entire harnesses? I haven't found any actual bad connections or wires, yet. But the truck is almost 9 years old with 535,000 miles and if I have to remove the harnesses to properly fix them I'm thinking it might be a better investment to just replace them. Thoughts? Opinions? Usually if there's a question as to the future reliability of something I err on the side of caution and replace it, but at $2k for the 3 harnesses going to the ECM, it's not a trivial cost.

2: What particular products to people recommend for sealing/protecting exposed connections like battery/starter/alternator posts/terminals, ground locations, etc... I'm looking for actual brands/products that I can look up and compare. I've invested in new 4/0 cabling for all the major connections and I want to keep them in the best condition possible. Especially since I live in the Northeast and travel through the great road salt state, NY.

DDlighttruck · 01-10-2020, **(Subject: Electrical wiring )**

1- if you’re not having electrical issues, I’d just replace the wire loom. It’s fairly inexpensive, it just takes time to redo it.

2- Permatex or GumOut are two brands I use. One is a cleaner one is a sealant. Usually every fall I’ll take all the battery connections apart, clean them, then spray them down with the sealant. For other electrical spots I use dialectric grease, Grote or Permatex again I think.

RyanC · 01-10-2020, **(Subject: Electrical wiring )**

If no issues are present get a bigger loom and go right over the old loom. Dont take any of it off.. deal with that when you have an issue.

If you have only a few spots that are bad at corners or rub points use heater hose and and slit it open. Length wise wrap the harness and zip tie it in place. Write down each point and check it at your PMS for rub through.

Waterloo · 01-10-2020, **(Subject: Electrical wiring )**

Depending on the age of the truck, mine is ten, and I have seriously thought about purchasing a new engine harness. Those wires eventually go green, and there will come a time when these harnesses are no longer available...

JMBT · 01-11-2020, **(Subject: Electrical wiring )**

On the exposed connections, like battery terminals, starter terminals, chassis grounds,..etc I have found if you clean them good then spray them with cheap spray paint it works just as good as the expensive stuff. Do several coats.

Also while you are working on electrics, take all your connections apart, sensors, ECM connections, anything you can take apart, disconnect them, spray them thoroughly with contact cleaner then grease them with dielectric grease.

You can also go through both fuse boxes, especially the one outside in the engine bay, pull each fuse and relay, clean their prongs with emery cloth and apply a THIN coat of dielectric grease, then cleaner the contacts they plug into in the fuse box and plug them back in. It takes awhile to do all this but it will save you headaches down the road.

As always disconnect batteries before doing this kind of service.

Rawze · 01-11-2020, **(Subject: Electrical wiring )**

FOr the bigger wires, like the 4/0, I always solder the connections, not crimp them.. much higher reliability, and less chance of bad connection later on. - As far as sealing the ends (exposed copper after making the connections), I use cloth tape, painted with a thick coat of flex-seal (in the can, not the garbage spray they sell).--- lasts for years without worry.

cloth tape, you can get at walmart or on amazon. here is what i use... https://amzn.to/2sZCbB8

and flex-seal same thing ... https://amzn.to/37X0NsQ

Rawze · 01-11-2020, **(Subject: Electrical wiring )**

As far as the wire looms go, I would just inspect wiring and replace the split-loom wherever it was going bad + ensure it is somewhat sealed form collecting moisture, unless there were issues.

If you wanted to go all out, you could remove the whole harness and do entire thing with it off the vehicle, then re-install it.

BTW: I replaced my dual (+) and dual (-) '1/0'-gauge starter wires (they were going bad form corrosion, etc. ) with a single 4/0 red and black welding cable for each and the starter works better than it used to. - Have helped a few guys do the same since. -- https://amzn.to/3a50Gxx

DDlighttruck · 01-11-2020, **(Subject: Electrical wiring )**

(01-10-2020 )Waterloo Wrote: Depending on the age of the truck, mine is ten, and I have seriously thought about purchasing a new engine harness. Those wires eventually go green, and there will come a time when these harnesses are no longer available...

I had a lot of whacky issues with gauges last year, it all pointed to no communication from the ECM to the truck. Truck ran fine, drove fine, but at least 8 gauges like speedo and tach were dead. Changed the engine harness myself, about $1400, fixed everything.

The OP said he’s not having issues, but for me my harness was probably 15 years old and I felt that was a smarter way to go.

Waterloo · 01-11-2020, **(Subject: Electrical wiring )**

(01-11-2020 )DDlighttruck Wrote:
(01-10-2020 )Waterloo Wrote: Depending on the age of the truck, mine is ten, and I have seriously thought about purchasing a new engine harness. Those wires eventually go green, and there will come a time when these harnesses are no longer available...
I had a lot of whacky issues with gauges last year, it all pointed to no communication from the ECM to the truck. Truck ran fine, drove fine, but at least 8 gauges like speedo and tach were dead. Changed the engine harness myself, about $1400, fixed everything.

The OP said he’s not having issues, but for me my harness was probably 15 years old and I felt that was a smarter way to go.

If the truck is a keeper, being proactive and purchasing a new harness while they are still readily available is a smart thing to do in my book, because eventually these harnesses do get old, brittle and green. When that day comes, and you realize it is time, only to find out that they are no longer available... Then what do you do? Then you have a real mess on your hands. I would purchase now, and at least have it in reserve, because that day will eventually get here, especially if you run up north.