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1.7.3 Harness Inventory

Purpose

Catalogs each fabricatable wire harness in the build. A "harness" here = a discrete bundle of wires with a defined start connector, end connector(s), routing path, and BOM — something you'd lay out on a workbench and tape together as a unit.

This page is the index and system-wide view. The detailed, build-it-from-this specs (conductor tables, gauges, colors, lengths, protection, connectors) live on the three build sheets below — each pairs the harnesses with the LJ Tub Map diagram that shows their physical routing.

Use these docs to:

  • Order connectors and lugs in correct quantities
  • Plan fabrication order (build harnesses bench-side, install in vehicle)
  • Identify reuse / consolidation opportunities
  • Define service-replaceable units (one harness fails → replace just that segment)

Bundling philosophy: Each harness terminates at a connector at every transition point (firewall, body penetration, distribution box). This makes harnesses individually serviceable and lets you lay them out flat for fabrication. The cost is more connectors; the benefit is much easier R&R.

Numbering note: Two prior bundles (the old H1+H4 power trunk and the old H6+H7 rear cabin bundle) were merged in May 2026. The catalog was renumbered to a single sequence H1–H9 — there are no compound names (no "H1/4", no "H6/7"). See the interference assessment for why the merged bundles are safe.

Harness Build Sheets

Each build sheet embeds the matching tub-map diagram and the workbench specs for the harnesses it shows.

Build sheet Tub-map page Harnesses
Power Distribution Power Distribution H1 Passenger Rear Power Trunk · H2 START Engine Bay Trunk · H3 BCDC Cross-Cab
Lighting & SwitchPros Lighting & SwitchPros H4 SwitchPros Front Bundle · H5 Rear Cabin Trunk Bundle
Controls, Recovery & Drivetrain Controls, Recovery & Drivetrain H6 ARB Compressor · H7 Winch Trigger · H8 Kilduff Shifter · H9 TCU to Engine Bay

Harness Summary

# Harness Build sheet Conductors Largest gauge Length
H1 Passenger Rear Power Trunk (AUX fwd + winch) Power 3 2/0 AWG ~13 ft (+13 ft winch to bumper)
H2 START Engine Bay Trunk Power 3 2/0 AWG 6–8 ft
H3 BCDC Cross-Cab Power 2 1/0 AWG ~5–6 ft
H4 SwitchPros Front Bundle Lighting 3 outputs 14 AWG 4–8 ft
H5 Rear Cabin Trunk Bundle (SP rear + PMU rear) Lighting ~10 14 AWG 8–14 ft
H6 ARB Compressor Controls 4 6 AWG ~10 ft
H7 Winch Trigger Controls 5 18 AWG ~3 ft + ~13 ft
H8 Kilduff Shifter → TCU Controls 1 (multi) Proprietary ~3–5 ft
H9 TCU → Engine Bay Controls 6 14 AWG 3–4 ft

Wire Color Convention

Colors on the build sheets follow this convention. Power and ground colors are universal automotive practice; signal colors are the builder's choice — pick a consistent scheme and keep it the same across every harness.

Wire role Color Notes
Power / positive feed (+) Red All constant/switched +12V distribution, feeds, and high-current power
Ground / negative (−) Black All returns and battery negatives
CAN bus Twisted pair Keep the pair twisted; do not split. Color per controller (e.g., J1939)
Vendor-supplied harness Per vendor pigtail SwitchPros (Delphi), ARB, CH4X4, Kilduff/ZF ship their own colors — match the supplied pigtail
Signal / trigger / output (non-vendor) Builder's choice Choose a consistent scheme and record it

For protective wrap/loom, heat sleeve, abrasion sleeve, and P-clamp standards by location, see Wire Protection Standards. This build wraps power runs in braided sleeve with per-harness tracers — see Protective Sleeve & Tracers.

Protective Sleeve & Tracers

Wrap preference for this build:

  • Power runs use braided expandable sleeve (PET, e.g. Techflex Flexo PET) over the full length, sized to the bundle OD. Braided sleeve is abrasion-resistant, flexes around the sill / trans-tunnel path, and lets you fan branches out without cutting the wrap.
  • Tracers identify each power trunk. Braided sleeve is sold plain or with a contrasting tracer stripe woven in. A per-harness tracer color makes bundles identifiable where several run together (e.g. in the cabin trunk). Suggested scheme — builder's choice, adjust to taste:
Harness Sleeve Suggested tracer Carries
H1 Passenger Rear Power Trunk Red braided Black AUX forward feed + winch power/ground
H2 START Engine Bay Trunk Red braided Yellow Alternator, starter, PMU feed
H3 BCDC Cross-Cab Red braided Green BCDC input + cross-ground reference
H6 ARB Compressor (motor pair) Red braided Blue 2× 6 AWG compressor motor cables
  • Heat sleeve still applies where any run enters the engine bay within ~12" of exhaust — over the braided sleeve as needed.
  • Split loom remains fine for the small-wire signal/lighting bundles (H4, H5, H7, H9) and for short, branchy, or frequently-accessed runs where braided sleeve is awkward; use a braided sleeve with a tracer instead if you prefer to color-code those too. H8 ships as a factory harness (no added wrap needed beyond loom through the tunnel).

Harness Map

                  ┌──────────────────────────────────────────────────┐
                  │                  ENGINE BAY                       │
                  │                                                   │
  H2 START trunk ─►──┐                                                │
                     │ alt, starter, PMU feed, BCDC input             │
                     │                                                │
                     ▼                                                │
                  ┌─────┐                                             │
                  │ PMU │◄────── H4 SP front ◄──┐                     │
                  └──┬──┘                       │                     │
                     │                          │                     │
  ═════════════════════════════════ FIREWALL ═════════════════════════│
                     │                          │                     │
                     ▼ HDP24                    │                     │
                  ┌──────────────────────────────────┐                │
                  │  FIREWALL CLUSTER (cabin side):  │                │
                  │  SwitchPros + GND bus + BODY PDU │                │
                  │  + Firewall CONSTANT bus + CBs   │                │
                  │  (audio amp on direct AUX feed)  │                │
                  └────┬──────────────┬──────────────┘                │
                       │              │                               │
                       │      H5 Rear Cabin Trunk Bundle              │
                       │      (SwitchPros rear + PMU rear, ~10 cond)  │
                       │              │                               │
                       ▼              ▼                               │
                  ┌─────────────────────────────────────────┐         │
                  │  CABIN TRUNK                            │         │
                  │  Forward (passenger side): H1           │         │
                  │  Forward (driver side): H2              │         │
                  │  Rearward: H5 + CT4 turn + H6 signal    │         │
                  │  Cross-cab: H3 (under rear bench)       │         │
                  └────┬──────────────────────────┬─────────┘         │
                       │                          │                   │
                       ▼                          ▼                   │
       ┌─────────────────────┐         ┌────────────────────┐         │
       │ DRIVER REAR WELL    │         │ PASSENGER REAR WELL│         │
       │ • START battery     │◄────────│ • AUX battery      │         │
       │ • 250A + 80A CBs    │  H3     │ • 300A + 150A CBs  │         │
       │                     │ BCDC    │ • SafetyHub        │         │
       │                     │ cross   │ • BCDC             │         │
       │  H2 ↑ (3× 2/0 AWG)  │ (under  │  H1 ↑ (3 cables)   │         │
       │  driver floor/wall  │  rear   │  passenger         │         │
       │  to engine bay      │  bench) │  floor/wall to     │         │
       │                     │         │  3× bulkhead studs │         │
       └─────────────────────┘         │  at firewall;      │         │
                                       │  winch portion     │         │
                                       │  continues to      │         │
                                       │  front bumper      │         │
                                       │  H6 ARB compressor │         │
                                       │  → under pass seat │         │
                                       └──────┬─────────────┘         │
                                              │                       │
                                              ▼                       │
       ┌─────────────────────────────────────────────────────────────┐
       │  FRONT BUMPER (H1 winch portion terminates)                 │
       │  REAR CARGO BULKHEAD (H5 multi-pin breakout)                │
       └─────────────────────────────────────────────────────────────┘

Bundle Interference Assessment

Two harnesses (H1 and H5) bundle multiple originally-separate runs into a single sleeve. EMI/crosstalk evaluation:

H1 (Passenger Rear Power Trunk) — 1× 2/0 AWG forward feed + 2× 1/0 AWG winch power/ground:

  • All three conductors carry power only — no sense lines, no signal returns, no CAN/audio/analog.
  • Inductive coupling between adjacent power conductors is irrelevant for distribution (the coupled noise has no signal path to corrupt; loads see CB-protected DC).
  • Winch peak current (~400A, seconds) raises a strong transient B-field but does not couple to the parallel forward-feed cable in any way that matters at the firewall CONSTANT bus.
  • Verdict: no interference risk. Safe to bundle.

H5 (Rear Cabin Trunk Bundle) — SP lighting outputs + PMU OUT-21/22/23 + 1 SP trigger return:

  • SP OUT-6/7/10/12/13 are switched DC for lighting loads (14 AWG), not PWM.
  • PMU OUT-21/22/23 are switched DC for brake / reverse / parking tail signals (16 AWG), not PWM in this build (no dimming required; tail circuits run at full output when commanded).
  • TRIGGER-2 (18 AWG) is a switch return from the rear cargo rocker. SP triggers require sustained 12V to register; brief inductive transients from adjacent switched outputs are filtered by the SP input.
  • No CAN bus, no audio signal, no analog sensor wiring shares this bundle. (CT4 rear turn signals were considered for inclusion — they would also be switched DC and remain safe to add later.)
  • Verdict: no interference risk under current load profile. Safe to bundle. If a future change introduces PWM dimming on any PMU rear output, re-evaluate — twisted pair or shielding may be warranted for the TRIGGER-2 line in that case.

Other bundles (H2, H3, H4, H6, H7, H8, H9): Each is single-purpose with homogeneous content (H2 = power only; H3 = power + ground reference; H4 = SP outputs; H6 = ARB power + signal already noted as physically separable; H7 = trigger logic only; H8 = factory shifter harness; H9 = TCU connections, includes twisted CAN pair). No new bundling concerns.

Cabin Trunk Bundle Summary

The cabin trunk (trans tunnel / sill, firewall ↔ rear wheel wells) carries multiple harnesses in parallel. Total bundle inventory:

Direction Harness Cable count Largest gauge Path side
Forward (rear → firewall) H1 Passenger Rear Power Trunk (AUX fwd + winch power+gnd) 3 2/0 AWG Passenger sill/floor
Cross-cab H3 (BCDC inter-battery + cross-gnd) 2 1/0 AWG Under rear bench
Forward (driver rear → engine bay) H2 (alt, starter, PMU feed) 3 2/0 AWG Driver sill/floor
Rearward (firewall → rear) H5 Rear Cabin Trunk Bundle (SP rear outputs + PMU rear lighting) ~10 14 AWG Trans tunnel
Rearward (firewall → rear) CT4 rear turn signals 2 14 AWG Trans tunnel (could merge into H5)
Rearward (firewall → under pass seat) SwitchPros control + pressure (ARB) 2 14–18 AWG Trans tunnel (per H6 optimization)

Passenger sill/floor (H1): ~3 cables, ~1.5" OD bundle, terminates at 3× bulkhead studs at firewall

Driver sill/floor (H2): ~3 cables, ~1.5" OD bundle, terminates at heavy power grommet at firewall

Trans tunnel rearward (H5 + CT4 + ARB signal): ~14 conductors of small wire (14–18 AWG)

Suggested trunk wrap: 1.5"–2" braided expandable sleeve (preferred for the power runs) or split loom per side, tracer-coded per harness so the bundles stay identifiable — see Protective Sleeve & Tracers. P-clamp every 12–18".

Bundle Optimization Opportunities (Summary)

These were noted inline on the build sheets; consolidated here for review:

  1. ~~Old H4 + old H1 share rear-well → firewall path~~ Resolved (2026-05-30): Merged into single H1 Passenger Rear Power Trunk. Firewall transition uses a single sealed 2-piece rubber grommet (e.g., Steele Rubber) — cables run continuously, no service break. Bulkhead studs (Blue Sea 2203/2204) max at 250A and were underrated for the winch peaks (400A); Anderson SB175 was also undersized. Continuous-cable + grommet is WARN's documented standard for high-current firewall pass-through.
  2. ~~Old H6 + old H7 + CT4 rear turn + old H8 SP signal wires share cabin trunk → rear~~ Partially resolved (2026-05-30): Old H6 + old H7 merged into H5 Rear Cabin Trunk Bundle with single multi-pin breakout (Deutsch DT15 or AMP CPC ~15-pin) at rear cargo bulkhead. CT4 rear turn signals and ARB control wires could still join — pending decision.
  3. H5 sub-harness (firewall → rear breakout) is a single straight pull; R&R of any individual rear light becomes a pigtail swap.
  4. H6 motor cables only. Move control/pressure wires into H5 since they originate at SwitchPros.
  5. Front lockers + rock lights + fog in one bundle through SwitchPros firewall bulkhead to engine bay → grille area. Splice/breakout at front for fan-out.
  6. ~~HDP20 firewall connector pin budget~~ Resolved (2026-05-30): Split into two dedicated bulkheads — HDP24-24-29 for non-SP traffic (18/29 used, 11 spare) + HDP24-18-14 for SwitchPros forward outputs (6/14 used, 8 spare). SP harness stays Delphi-native end-to-end. See Pin Budget Audit.

Outstanding Items

  • Decide front bumper breakout connector style (Deutsch DT, AMP CPC, etc.)
  • Decide rear cargo bulkhead breakout connector style and pin count
  • ~~Calculate HDP20 firewall pin budget — fits or needs upsize?~~ → Resolved: Upsized to HDP24-24-29 (29 size-16 contacts, 21 used + 8 future headroom). See Pin Budget Audit for full pin assignment. Forward-going SP loads use chassis ground locally (1 pin per output instead of 2).
  • Confirm SwitchPros front locker wire routing (front axle access)
  • Decide if ARB control wires merge into H5 (recommended) or run as H6 signal pair
  • Source connector + lug + heat shrink BOM totals
  • Confirm braided-sleeve sizes and per-harness tracer colors for the power runs (see Protective Sleeve & Tracers); decide split loom vs braided for the small-wire bundles per zone
  • Define and record the signal-wire color scheme for non-vendor signal/trigger wires (power = red, ground = black are fixed; see Wire Color Convention)