harness issues

[knewbie79]

Hi there from the great white north. I purchased a 79 terra this summer and have been spending a lot of time researching Scout ll's in general for the past number of months. I've ordered a new engine and dash harness to give me a good base to start with.the terra is stock with a 304, points distributor, 4 speed, 44's front and rear,37 amp alt, no ac.what sort of issues will I face once the new harnesses are installed?

 

[Michael Mayben]

hi there from the great white north. I purchased a 79 terra this summer and have been spending a lot of time researching Scout ll's in general for the past number of months. I've ordered a new engine and dash harness to give me a good base to start with.the terra is stock with a 304, points distributor, 4 speed, 44's front and rear,37 amp alt, no ac.what sort of issues will I face once the new harnesses are installed?

When you say..."new harnesses" do you mean replacement oem harnesses or the aftermarket universal harnesses such as the kwikwire stuff we handle?

Are you retaining the oem instrumentation, adding to oem instrumentation, or going full custom?

What additional accessories/loads do you plan that you May not install now?

Are you considering a dual battery setup?

The primary consideration I'd determine is to eliminate completely any form of the two oem bulkhead connectors, those are problematic and superfluous.

I'd plan to feed your replacement load center/fuse panel from a maxifuse block or one of two types of fusible link systems. That would provide "master" system protection in addition to the protection for each load's wire run.

 

[knewbie79]

Thanks , I've been going through all the info/upgrades on this forum and looked through the solutions for the ills of the original system. The engine and dash harnesses are being made at superscout spec to oem spec. I'm keeping the stock gauges being they all work.seeing that I'm commited to harness purchase, what is the issue with the bulkhead connectors and what if anything can I do to improve or protect it? Rest assured, I will be doing the upgrades you recommend concerning the alt , grounding, starter relay, etc. The list grows! I'm concentrating on brakes, steering elec systems for now.suspension and body to follow. I want to end up with a truck that looks good enough for the local shows and runs well enough for a two week road trip.

 

[Michael Mayben]

thanks , I've been going through all the info/upgrades on this forum and looked through the solutions for the ills of the original system. The engine and dash harnesses are being made at superscout spec to oem spec. I'm keeping the stock gauges being they all work.seeing that I'm commited to harness purchase, what is the issue with the bulkhead connectors and what if anything can I do to improve or protect it? Rest assured, I will be doing the upgrades you recommend concerning the alt , grounding, starter relay, etc. The list grows! I'm concentrating on brakes, steering elec systems for now.suspension and body to follow. I want to end up with a truck that looks good enough for the local shows and runs well enough for a two week road trip.

The repop harnesses from light line/super Scout are virtually identical to the oem stuff including the bulkhead terminations. But more modern materials are used of course, I don't know about the actual bulkhead connectors themselves as I've yet to install one of these items though I have seen 'em laying in packages. I am impressed with the overall quality of the light line repop harnesses and materials used.

The actual polymer gang connectors were not the real issue. The problem is that the male/female terminations that are simply held into the gang connectors are not sufficient "ampacity" for the primary current feed to the ammeter/fuse panel. And the quality of the rubber/plastic from 1971-ish has certainly not survived the underhood elements all these years, no one knew back then what the longterm "quality" issues would be 30+ years down the line. Normal automotive component "durability" testing follows a prescribed cycle that replicates a minimum of a 100,000 mile lifecycle.

So when the actual brass terminations inside the connectors overheat due to corrosion/oxidation/overload, a cascade effect develops.

The breakdown in the bulkheads is not restricted to only the high current feed to the ammeter...in my opinion nearly all of the wire runs served by both connectors are under capacity (or barely adequate). They are fine if relays for headlights and other loads had been incorporated, but they were not. This issue is not "caused" by the inclusion of an ammeter in the ihc-produced electrical system scheme, that urban myth is bs.

When I do any vehicle wiring system from scratch, I use wire gauge at least one and usually two sizes greater in ampacity for the intended load in a 100% duty cycle. Due to weight and cost...no oem manufacturer ever did that!

The harnesses are long enough to be able to use some sort of terminal strip for interface once the bulkhead connectors are removed. That is one way of doing it. Marine-type terminal strips have an advantage of normally incorporating some sort of environmental protection if that's a concern. I use barrier strips sourced from radio shack all the time along with a jumper segment to tie the switched and unswitched feeds in if need be. Then I "paint" the metallic connections with liquid neoprene once everything has been completed and tested.

 

[knewbie79]

Thanks for the info on the oem harness and the comments on my replacement. So if I keep any add-ons, ie: driving lights, etc, on a seperate relayed power source. The lite line harness should handle the factory installed duties ok. The mods you folks recommend for the charging , starter relay and others look like projects I could do although I don't profess to be any kind of wizard of the wires. Thanks again! P.s. I also have an a.t.o. Type fuse block coming with the sss stuff I ordered.

 

[Michael Mayben]

Auxiliary lighting such as fog/driving lamps, etc. Need to be "relayed" if using the typical very low ampacity switches contained in most of those imported "kits".

When I install lights such as those "from scratch" (light fixtures sourced individually), I use a suitable high ampacity switch(s), with appropriate gauge wire runs/terminations so that I don't have to use relays which I consider a failure point. I normally run that stuff from an auxiliary load center installed just for that purpose, and the auxiliary does not pull through the oem ammeter circuit.