| Parameter | Details |
|---|---|
| Product Name | External Wiring Harness (Boom / Stick / Cab Exterior Harness) |
| Part Numbers | 251-0277 (also 2510277), 186-4605 (also 1864605) |
| Compatible Brands | Caterpillar (CAT) |
| Compatible Excavator Model | CAT 320C |
| Harness Type | External / Boom & Stick Harness (As-Fitted) |
| Material | Copper wire + PVC/TPE insulation + Rubber seals |
| Packing | PP bag inside, carton box outside |
| Payment Terms | Western Union, L/C, T/T, MoneyGram, D/A, D/P |
| MOQ | Acceptable trial order (1 piece accepted) |
| Shipping Mode | Air/Sea/Express (FedEx, UPS, DHL, TNT, etc.) |
| Place of Origin | Guangdong, China |
| Brand Name | COGENG |
| Certification | ISO9001 |
| Stock Status | ✅ In Stock |
| Supply Capacity | 500 PCS |
The COGENG 251-0277 / 186-4605 External Wiring Harness is a premium-quality, direct OEM replacement wiring assembly specifically designed for the Caterpillar 320C hydraulic excavator.
The 320C is a legendary medium-class excavator produced from the early 2000s, powered by the CAT 3066 or C-6.6 engine. Unlike the newer D-Series which utilizes extensive CAN-bus communication, the C-Series relies on a more traditional 12V/24V electrical architecture. This makes the external harness simpler but requires high-quality copper wiring to ensure reliable switching for lights and solenoids.
This External Harness is the wiring that runs on the outside of the machine—specifically along the cab roof, boom, and stick. It is responsible for:
Cab Roof Lighting: Rotating beacon, cab work lights.
Boom & Stick Work Lights: Illuminating the worksite.
Hydraulic Quick Coupler: Wiring for engaging/disengaging attachments.
Attachment Sensors: Pressure switches for auxiliary circuits.
Boom & Stick Position Sensors: (If equipped).
Given its location, this harness is constantly exposed to extreme UV rays, rain, mud, rocks, branches, and continuous flexing at the boom and stick pivot joints. The COGENG replacement is built with UV-resistant PVC insulation, tin-plated copper conductors (to prevent corrosion), and IP67 waterproof connectors to ensure longevity.
Why Choose COGENG 251-0277 / 186-4605?
Dual Part Number Coverage: 251-0277 is the primary part; 186-4605 is often used for machines with longer sticks or specific light configurations. We supply the correct one based on your stick length.
Plug-and-Play: No splicing or crimping required.
Heavy-Duty: Designed to withstand the rigors of the C-Series era.
In Stock: Ready for immediate shipment.
| Component | Quantity | Description |
|---|---|---|
| Main External Trunk | 1 | Runs from cab roof to bucket tip. |
| Cab Roof Branch | 1 | Beacon, mirror lights, roof light. |
| Boom Section | 1 | Lower/Mid boom lights, coupler solenoid. |
| Stick Section | 1 | Stick lights, stick position sensor. |
| Bucket / Tip Branch | 1 | Bucket light, end-of-stick connectors. |
| Connectors | As req'd | Deutsch / Packard / Sure-Seal (pre-attached). |
| Cable Ties & Clips | As req'd | OEM-style push mounts. |
| Protective Corrugated Loom | Full length | Abrasion and heat resistance. |
| Machine Model | Engine | Compatible Harness | Notes |
|---|---|---|---|
| CAT 320C | 3066 / C-6.6 | 251-0277 | Standard boom/stick |
| CAT 320C L | 3066 / C-6.6 | 251-0277 | Long undercarriage |
| CAT 320C | 3066 / C-6.6 | 186-4605 | Long stick version |
| CAT 320C FM | 3066 / C-6.6 | 186-4605 | Forestry machines |
| CAT 320D | C6.6 | Not compatible | Different electrical architecture |
| CAT 320B | 3066T | Not compatible | Different connectors |
⚠️ Important Verification: 251-0277 is typically for standard sticks (2.9m). 186-4605 is typically for long sticks (3.7m+) or machines with additional auxiliary lighting. Please measure your stick length or provide your Serial Number.
✅ Direct OEM replacement for:
CAT Part Number: 251-0277
CAT Part Number: 186-4605
✅ Designed For:
CAT 320C (Standard, L, LN variants)
CAT 320C U (Utility)
CAT 320C FM (Forestry)
⚠️ Critical Verification Checks:
Stick Length: The 320C came with sticks ranging from 2.9m to 3.7m. *The 251-0277 fits the shorter stick; 186-4605 fits the longer stick.*
Coupler Wiring: If your machine has a pin-grabber coupler, ensure you have the correct hydraulic solenoid connector (included).
Beacon Mount: Ensure your beacon wiring is intact (some 320Cs have the beacon on the left, some on the right).
❌ NOT Compatible With:
CAT 320D – Uses multiplexed CAN-bus for lights; plugs are different.
CAT 320C with Mass Excavation boom (shorter boom – harness too long).
CAT 312C or 315C (smaller frames).
CAT 320C with a factory-installed cab riser (requires an extension harness, not included).
Step 1: Preparation
Fully lower the boom and stick to the ground.
Disconnect the batteries (negative first).
Open the rear cab roof cover.
Step 2: Removing the Old Harness
Label everything before you disconnect.
Disconnect the cab roof bulkhead connector.
Trace the harness down the boom. Use a flathead screwdriver to pop the plastic clips.
At the boom-stick joint, disconnect the stick harness section.
Remove the old harness.
Step 3: Installing the New Harness
Start from the Cab Roof and work towards the bucket.
Service Loop Installation: At the boom-stick joint, ensure there is a droop loop of approximately 20-30cm. This is critical to prevent the harness from snapping when the stick is curled in.
Connectors: Plug all connectors in until they "click."
Clips: Secure the harness using the provided OEM-style push clips.
Step 4: Testing
Reconnect batteries.
Turn the key to "ON" (do not start).
Check all lights: Beacon, Cab, Boom, Stick, Bucket.
Test the Quick Coupler (engage/disengage).
Q1: What is the difference between 251-0277 and 186-4605?
A: They are both external harnesses for the 320C, but:
251-0277: Typically for standard stick length (2.9m).
186-4605: Typically for long stick length (3.2m - 3.7m) or machines with additional lighting brackets. If you have a long stick, you need 186-4605.
Q2: Is this a genuine CAT part?
A: No. COGENG is an aftermarket manufacturer (ISO9001) . Our parts are built to OEM specifications, offering the same fit and function at a reduced cost.
Q3: My 320C only has one boom light, but this harness has two. Does it matter?
A: It does not matter. The extra connector is an optional spare. Simply leave it safely coiled and zip-tied if not in use.
Q4: What voltage does this harness use?
A: The CAT 320C operates on a 24V electrical system. This harness is rated for 24V DC.
Q5: Does this harness include the quick coupler wiring?
A: Yes. Both 251-0277 and 186-4605 include the pre-wired connector for the hydraulic quick coupler solenoid located at the boom foot.
Q6: The harness goes right under the cab door – how do I protect it?
A: The harness includes a heavy-duty rubber grommet at the cab roof exit point. When installing, ensure this grommet is fully seated to prevent water ingress.
Q7: How long does shipping take?
A: Express shipping (DHL/FedEx) takes 3-7 business days worldwide.
Q8: How do I place a trial order?
A: Contact your COGENG distributor. MOQ is 1 piece.
| Parameter | Value |
|---|---|
| Harness Length | ~8 – 12 meters (depends on stick length) |
| Wire Gauge | 0.5 mm² – 2.5 mm² |
| Insulation | UV-resistant PVC + Braided Nylon |
| Temperature Range | -40°C to +125°C |
| Voltage | 24V DC |
| Key Connectors | Deutsch DT (2-pin, 3-pin), Sure-Seal |
| HS Code | 85443000 |
| Component | Connector Type | Typical Pinout |
|---|---|---|
| Rotating Beacon | 2-pin Deutsch | Pin 1: +24V, Pin 2: Ground |
| Boom Light | 2-pin Sure-Seal | Pin 1: +24V (Switched), Pin 2: Ground |
| Stick Light | 2-pin Sure-Seal | Pin 1: +24V (Switched), Pin 2: Ground |
| Bucket Light | 2-pin Sure-Seal | Pin 1: +24V (Switched), Pin 2: Ground |
| Coupler Solenoid | 2-pin Deutsch | Pin 1: +24V (Engage), Pin 2: Ground |
| Boom Sensor | 3-pin Deutsch | Pin 1: +5V Ref, Pin 2: Signal, Pin 3: Ground |
To ensure we ship the correct part (251-0277 vs 186-4605), please provide:
Machine Model: CAT 320C (or 320C L).
Stick Length: (e.g., 2.9m, 3.2m, 3.7m) – This is critical!
Serial Number: (e.g., BNM00123, RCP00123).
Old Part Number: (If the tag is still readable on the old harness).
✅ In Stock – Ready to Ship.
✅ MOQ 1 piece accepted for trial orders.
📞 Contact COGENG supplier today to place your order!
*Shipping Details Delivery Return*
Sales Price:
The displayed price is for reference only. Please contact COGENG sales support for the exact price.
Shipping Method:
Sea, land, or air transport; the specific method is determined based on the nature of the shipment.
Estimated Delivery Time:
Based on the dispatch time from the logistics carrier; the displayed arrival time serves as the reference.
Contact information is provided at the bottom of the page.
Merchant Return Policy:
Products shipped are not eligible for return or exchange.
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