3.1 Continuity, Hipot & Resistance

ElectricalCrimping harnesses areis the nervousmost systemcritical ofprocess anyin electronicwire system,harness andassembly. testing themIt is aboutnot provingmerely bothfolding functionalitymetal andaround safety.a Fromwire; simple continuity checks to high-voltage stress tests, each methodit is a safeguardprecision againstmetallurgical defectsprocess that couldcreates causea failurespermanent, inelectrically conductive joint. A proper crimp transforms the fieldwire orstrands hazardsand terminal into a solid metal mass, achieving reliability often superior to operators.soldering. RunningHowever, thesebecause teststhe in a logical sequence not only prevents costly mistakes but also builds trust that every harnessconnection is solid,hidden traceable,inside the metal barrel, verifying its quality requires strict adherence to geometry and readytooling for service.setups.

3.1.1 The planPhysics (orderof matters)Crimping: Cold Welding

RunThe testsgoal inof thiscrimping sequenceis soto you find cheap problems first and keep operators safe:

1. Continuity & shorts (low-voltage net check).
2. End-to-end resistance (does the metal match the math?).
3. Insulation Resistance (IR) (DC at high voltage).
4. Hipot (high-voltage stress with ramp, dwell, discharge).

If a step fails, stop and contain—don’t “see what happens” at higher stress.

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3.1.2 Continuity & shorts (the fast netlist truth)

Goal: verify opens, shorts, and miswires against your From–To table (19.2).

Method

• Usecreate a bed-of-nailsgas-tight harness tester or mating connector box; load the netlist by PN/Variant (scan to select).
• Stimulus: 5–20 V current-limited (≤20 mA is plenty).
• Continuity threshold (starter): ≤ 3 Ω or (R_calc + margin), whichever is higher (see 21.1.3).
• Shorts threshold (starter): ≥ 1 MΩseal between unrelatedthe nets.

terminal

Tips

• Treat shields/chassis as their own nets.
• Use guided probe mode for debug (lights show whereand the miswireconductor. is).
• ForThis multi-branchis looms,achieved testthrough submodulescontrolled beforephysical final loom-up to isolate faults fast.

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3.1.3 End-to-end resistance (does the number make sense?)

Measure each conductor’s DC resistance; compare to a smart limit.

Quick math

R_expected = (Ω/m from gauge) × length_along_centerline

Add contact allowance: ~20–50 mΩ per mated contact (two ends → 40–100 mΩ).

Starter limits

• Pass if R_measured ≤ (R_expected × 1.5) + contact_allowance.
• Flag asymmetry: matching-length mates should be within 10% of each other.

Low-ohm conductors (power, <100 mΩ): use 4-wire (Kelvin) measurement to avoid lead error.

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3.1.4 Insulation Resistance (IR)

What: DC voltage applied between conductors (and to shield/chassis) to measure MΩ/GΩ.

Why before Hipot: finds moisture/contamination gently.

Starter setup

• Test voltage: 500 VDC (typical low-voltage harness). Use 250 VDC for sensitive electronics or per spec; 1000 VDC for heavy-duty looms if required.
• Dwell: 60 s (or 30 s + 5 s/m of cable length for very long runs).
• Limits (defaults—tighten per customer):
• • Indoor/benign: ≥ 100 MΩ.
  • Harsh/automotive: ≥ 10 MΩ minimum, ≥ 100 MΩ preferred.
  • High-reliability boxes: ≥ 1 GΩ.

Notes

• Temperature/humidity affect IR. If borderline, retest in spec environment (5.2).
  

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3.1.5 Hipot (with respect,compression, not fear)

What: apply high voltage to prove no breakdown under stress.

DC vs AC

• DC Hipot (most harnesses): cleaner leakage reading; easier on capacitive loads.
• AC Hipot (some specs): stresses alternately; leakage limit is in mA RMS.

Starter DC setup (follow customer spec if given)

• Voltage: 500–1000 VDC for low-voltage harnesses.
• Ramp: 1–2 s up to setpoint.
• Dwell: 2–3 s + 0.3 s/m of harness length (capacitance driven).
• Trip/leakage: set 0.5–2.0 mA depending on length/capacitance; use the lowest value that avoids nuisance trips.
• Discharge: active discharge to <30 V before PASS/FAIL clears or the door unlocks.

Pairs to test

• Every signal net ↔ all others commoned.
• Power rails ↔ shield/chassis.
• Shield ↔ cores (if single-ended bond strategy, still Hipot for breakdown).
  

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3.1.6 Fixtures & variants (ban pin damage and mix-ups)

• Prefer mating connectors or guided pogo blocks; no raw pin stabbing.
• Keyed plates and pin-1 triangles on fixtures; color bands per variant.
• Test program chosen by scanning the harness SN or cart; the tester blocks start on mismatch.

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3.1.7 Safety (non-negotiables for Hipot/IR)

• Interlocked enclosure with door switch; two-hand or guarded start.
  Red beacon and HV signage during test.
• Bleed-down with indicator; door stays locked until safe.
• Guarded HV leads, rated probes; no alligator clips on bare metal.
• One-hand rule training; ESD strap OFF during Hipot.
• Emergency stop within reach; daily functional check.
  

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3.1.8 Recording & traceability (make it audit-proof)

Each unit record (SN or lot) should store:heat.

• ProgramPlastic ID / limitsDeformation: As the crimp dies close, the terminal barrel wraps around the copper strands. The pressure is high enough to exceed the yield strength of both the copper and the terminal material (plastic deformation), operator,but not their fixtureultimate IDtensile strength (breakage).
• Continuity/shortsCold Welding:: pass,Under failingthis netsimmense ifpressure, any.the oxide layers on the individual wire strands and the terminal interior are scrubbed away. The clean metal surfaces are forced into intimate contact, causing atoms to share electrons across the boundary. This fusion is a "cold weld."
• ResistanceThe Gas-Tight Seal:: measuredA valuessuccessful crimp compacts the strands so tightly that no air (oxygen) or maxcorrosive pergases family.can enter the interstitial spaces (voids). Without oxygen, the connection cannot oxidize, ensuring low contact resistance for the life of the product.
• IR/HipotThe Honeycomb Effect:: voltage,In dwell,a cross-section (micrograph), a good crimp looks like a solid honeycomb. The individual round strands are deformed into polygons, eliminating air gaps.

3.1.2 The Crimp Zone: Anatomy of a Terminal

A reliable crimp is defined by specific geometric features. Each zone serves a mechanical or electrical function.

A) The Conductor Crimp (The Electrical Core)

This is the area where the cold weld occurs.

• maxThe leakageCrimp: The metal wings are folded down and curled inward into a "B" shape (F-Crimp), result;compressing timestamp.the strands.
• PhotosTarget: (endsAll vsstrands golden)must ifbe yourcaptured; flowcompression requiresmust them.
  
  be Tie thissufficient to eliminate voids (typically 15-20% reduction in cross-sectional area).

B) The Bellmouth (The Strain Relief)

The bellmouth is the flared edge at the entry (and sometimes exit) of the conductor barrel.

• 20.5Function: genealogyIt automatically—noacts screenshotsas livinga funnel to guide the wire in and, more importantly, prevents the sharp edge of the crimp tool from cutting the wire strands during flexing.
• Mandate: A visible bellmouth is mandatory at the wire entry side.

C) The Brush (The Extension)

The "brush" refers to the wire strands protruding past the conductor crimp barrel.

• Function: It confirms that the wire passes all the way through the crimp zone, ensuring full electrical contact along the entire barrel length.
• Limit: The brush must be visible but not so long that it interferes with the mating connector or locking mechanism.

D) The Insulation Crimp (The Mechanical Support)

This rear section grips the wire's insulation.

• Function: It provides strain relief, absorbing vibration and bending forces so they are not transferred to the electrical crimp.
• Target: The insulation crimp should firmly grip the wire without piercing the insulation to the point of touching the conductor.

3.1.3 Applicator Setup: Matching Feed and Geometry

The Applicator is the tooling assembly inside the press that feeds terminals and houses the crimp dies. Setting it up correctly is the first line of defense against defects.

A) Die Geometry and Wire Gauge

The crimp dies are machined for a specific range of wire gauges. Using a die designed for 18 AWG on laptops.a 22 AWG wire results in under-compression (loose wire). Using it on a 16 AWG wire results in over-compression (crushed strands/cracked terminal).

• Verification: The operator must verify the
  Terminal Part Number matches the Wire Gauge and the Applicator ID listed on the work instruction.

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B)

Terminal Feed Alignment

The applicator feeds the terminals onto the anvil.

• 3.1.9Feed TypicalTiming: limitIf startersthe feed is too slow, the terminal is crushed by the crimper. If too fast, the "cut-off tab" (tunethe metal scrap) is too long.
• Centering: The terminal must sit perfectly centered on the anvil. If it is misaligned, the crimp wings will curl unevenly, creating a "banana" or twisted crimp.

C) Crimp Height Setting

The applicator allows for micro-adjustment of the crimp height (shut height).

• The Dial: Most applicators have a rotary dial to youradjust product)the

  Harnesscrimp type	Continuity	Shorts	IRheight @in 5000.02 VDC	DCmm Hipot
  Signalincrements. loomThis (indoor)	Ris ≤the Rexp×1.5primary +knob 0.1Ω	≥used to dial in the 1Crimp MΩ	≥Height 100 MΩ	500–700 VDC, ≤1 mA, 2–3 s
  Power loomMeasurement (≤15 A)	4-wire on power lines; ≤ 1.5× Rexp	≥ 1 MΩ	≥ 50–100 MΩ	700–1000 VDC, ≤2 mA, 3–5 s
  Shielded sensor	As above	≥ 10 MΩ	≥ 100–1000 MΩ	500–700 VDC, ≤1 mA

  Use customer/standard limits when specified. These are starting pointsCHM) to getmeet youthe safelygas-tight productive.specification.

  
  

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3.1.10Final CommonChecklist: trapsCrimp → smallest reliable fixFundamentals

TrapMandate	SymptomCriteria	FixVerification Action
Bellmouth Check	TestingA HipotBellmouth beforemust continuitybe visible at the wire entry side.	ExplodingVisual defects	Runinspection continuity(10x first;mag). contain,Absence thenindicates IR/Hipota risk of cut strands.
Brush Visibility	NuisanceWire Hipotstrands trips(brush) onmust longprotrude loomspast the crimp barrel.	FailsVisual withinspection highconfirms capacitivefull inrush	Addwire ramp, raise dwell, set realistic trip; use DC Hipot
Crushed or bent pins	High rework, latent fails	Use mating fixtures, not raw pin probesinsertion.
ResistanceGas-Tight fails on long runsSeal	“Bad”Crimp butgeometry reallymust long	Useeffectively R_expectedturn mathstrands +into contacta allowance;solid switch to Kelvin
Mixed variants on same fixture	Cross-wiresmass.	Scan-to-selectMicro-section analysis program;during colorsetup bandsvalidation shows "honeycomb" compression and keyedno nestslarge voids.
Insulation Support	NoInsulation dischargecrimp waitmust grip the jacket firmly.	Bend Test: Insulation should not pull out or rotate when the wire is flexed.
Tooling Match	Die set must match the specific wire gauge and terminal.	OperatorValidation shockof risk	Interlockthe +setup bleedsheet toagainst <30the Vphysical beforetooling door openstags.

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3.1.11 Pocket checklists

Before test

• Program/limits loaded by scan (PN–Rev–Variant)
• Fixture ID & orientation OK; connectors seated
• Visual: TPA/CPA locked, labels readable, boots cooled

Continuity/Resistance

• Continuity pass; no shorts
• Power lines 4-wire measured; results logged

IR/Hipot

• Door closed; beacon on; ESD strap off
• Ramp/dwell set; trip current appropriate for length
• PASS; discharge complete; door unlocks

Closeout

• Results attached to SN/lot in MES
• Fails to NG-QUAR with netlist of defects
• Fixture condition check; pins undamaged
  

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By applying continuity, resistance, insulation, and hipot tests in the right order with safe fixtures and clear records, manufacturers eliminate hidden faults before they escape. The result is faster troubleshooting, lower risk, and harnesses that customers can rely on without hesitation.