Caterpillar 420E Engine ECU Wiring Harness
Engine ECU Wiring Harness for Caterpillar 420E excavator. OEM part 290-6751. Direct replacement.
Fitment
Fits the Caterpillar 420E Excavator. ECS lists 4 harness sections for this machine — see all 4 sections for the Caterpillar 420E before you order, because the sections are not interchangeable.
Part number reference for the 290-6751
This harness is one part sold under one number. Suppliers and parts books write it differently — you may see it as 290-6751, 2906751 · CA2906751. They are all the same part; the number on the tag of your old harness is what settles the order.
If the tag shows a different number entirely, do not order by eye — send us a photo of it on WhatsApp and we will match it against the catalogue before anything ships.
Where this harness sits on the Caterpillar 420E
It sits between the controller box and the machine harness, in the cab or behind a panel, and carries the low-level inputs and outputs the controller reads.
What it connects
- Controller pins to the machine sensors and actuators — the individual channels, one run per input or output.
- Power and ground to the controller — the supply that the controller will not run without.
- Data link between controllers — the CAN or serial pair that lets the modules talk.
What a failing Caterpillar 420E harness looks like
| What the operator reports | Why the harness fits that symptom |
|---|---|
| Controller dead or rebooting | Supply and ground first, then the connector at the box. |
| Multiple channel faults on one controller | A shared connector or a shared ground in this harness. |
| Data link faults between modules | The twisted pair or its shield, not the modules themselves. |
| Fault disappears when the connector is reseated | Terminal tension or corrosion in this harness, not the controller. |
These are circuit-level symptoms, not a diagnosis. The same behaviour can come from a sensor, an ECM input or a mechanical fault — the checks below are how you tell them apart.
How to confirm it is the harness before you buy
- Compare the part number on the old harness. The number is printed on a tag or moulded into the main connector body. If it does not match, stop — stop here and send us a photo, because two sections of the same machine are not interchangeable.
- Resistance test the suspect run. Disconnect both ends and measure end to end. A reading that is far above the others in the same loom means broken strands; a reading to ground means chafing.
- Wiggle test under load. Back-probe the circuit with the machine running and flex the loom by hand along its length, especially at clips and at the cab or boom entry. If the meter or the fault jumps, you have found the run.
Other harness sections for the Caterpillar 420E
Same type of harness on other machines
Product Description
Engine ECU Wiring Harness for Caterpillar 420E excavator. OEM part number 290-6751. Direct replacement ensuring plug-and-play installation.
Why Choose ECS System Parts?
- Factory Direct: we build the loom — no middlemen
- In Stock Ready to Ship: most orders leave within 24 hours
- OEM Quality: made to the original drawing, connector for connector
- 1 Year Warranty: full coverage against defects
- Worldwide Shipping: DHL, FedEx, UPS, EMS
- Expert Support: WhatsApp +86-13714733803 — send us a photo of your old harness and we will confirm the section
Technical Specifications
| OEM Part Number | 290-6751 |
|---|---|
| Compatible Model | Caterpillar 420E Excavator |
| Harness Type | Engine ECU |
| Warranty | Packaging Machine Normal Use |
Shipping Information
- DHL / FedEx / UPS / EMS worldwide
- Ships within 24 hours
- 3-7 days express, 7-15 days standard
- Tracking number provided
Return Policy
- 30-day return window
- Must be unused, original packaging
- Contact via WhatsApp for RMA authorization