A 1986 K10 should not have the Electronic Quadrajet, or ESC distributor so it's a fairly simple engine harness. No oogie boogies like more modern cars and trucks with legions of sensors to control and monitor the fuel and emissions systems.
Most aftermarket replacement harnesses are one-size-fits-all. They are not terminated for factory plugs. AAW may be different but if they actually "drop in and plug in" with no final terminations needed you'll pay dearly for the privilege.
I've generally found it's far easier to repair or replace individual wires causing problems than replace it all.
-SXL jacketed wire is available from many online sources pretty cheaply... I've found SXL, GXL, and TXL (cross-link Polyethylene) single color wire and even more exotic stuff like cross-link poly jacketed wire with various color tracer stripes in project lengths like 25' on evilbay.
-Near Professional grade tooling for the handful of terminal families present on the 73-91 CK RV trucks (Packard 56/59, Pak-Con, Weatherpak, and Metripak 150/280/480/630) is far less expensive than than the price of most "drop in" harnesses that aren't... My good tooling for these would cost about $300 to replace.
--Ideal Stripmaster 10-20ga is $30 from the Borg (Lowes or Home Depot) Once you use em you'll wonder why the heck you put up with those crappy $5 Wally World wire strippers or even the mildly better quality $15 Belden/Klein variety.
--Delphi 12085270 & 12085271 and clones are the most versatile crimp tools in my arsenal. They cost right around $100 each and will handle every GM terminal you're likely to run into in two steps... conductor cavity then insulation or connector seal are crimped in separate steps by different cavities in the tools. The ratcheting action guarantees the crimp is at full pressure for a good solid mechanical bond from the conductors to the terminal.
--SIR-Tools 9024 & 9025 terminal extractor sets can be had for around $30 each Get both. The cheaper Lisle discs work just as well but they don't fold up so they are more prone to damage when dropped and harder to use without impaling your hand. Add my $10 little green Xcellite precision screwdriver to the mix and you're set to disassemble every GM connector on these trucks including the fuse-relay panel for less than $100.
--Crescent S2KS5N is a set consisting of the very good Xecelite 170M general purpose electronics dikes along with some dubiously useful pliers. This set is by the Borg (Home Depot) for around $14. They are my go-to dikes for 12ga and smaller automotive wire and a lot of electronics projects.
There are at least four and as many as seven sub-harnesses that terminate in the engine bay one way or another. POWER, Forward lamps & horn, engine, HVAC, Battery/charge, and sometimes NL2 Dual tanks. Even inside the cab there are really several sub harnesses not an all-encompassing oogie boogie "cab harness". When you break it down this way it becomes far less intimidating to work on. I say to myself "All I care about is these X wires for this task and they are these colors.".
Each sub-harness on these trucks only has a few wires.
-The main power feeds have fusible link connections to the starter BAT stud and the firewall J stud. They're big red wires to black slightly smaller gauge fusible links. Usually you don't need to mess with them.
-The charge system is three wires and one of those is the Huge 10AWG charge wire. One goes back to the bulkhead plug. The other two go to the starter BAT stud and/or the big hairy Junction stud on the firewall.
-The start system is one Purple wire and the big 4awg cables from the battery.
-The engine itself really only has three circuits (IGN power to the HEI cap, Oil, and Temp)... These are usually a single color wires without a tracer stripe.
-NL2 dual tanks have three wires running through the engine bay.
-Forward lamps and Horn only have six power wires. They run along the inner LH fender and the rad support. All lamp grounds go to the rad support.
-Rear lamps have four wires plus the fuel sender that generally run along the LH frame rail from their ends to the bulkhead. The rear lamp harness is literally 4 wires with Weatherpak terminals on one end and Packard 56 male terminals on the other end. I've made several of these to replace U-Haul butchered tail lamp wiring.
-HVAC is the most complex but it's a sub harness that can be easily liberated from a donor and usually can be repaired if needed.
-There could also be manual-transmission backup lamp wire or 3-4 wires for the TH350/TH700R4 TCC lockup or a TH400 kickdown wire but again it's 1-4 wires not a harness the size of your fist.
1
