Caterpillar 420E Engine Wiring Harness

Part number reference for the 263-9484

This harness is one part sold under one number. Suppliers and parts books write it differently — you may see it as 263-9484, 2639484 · CA2639484. 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 runs inside the engine compartment, clipped along the block and head and routed past the front cover. On most machines it is the longest harness on the engine side and the one closest to exhaust heat.

What it connects

• ECM to the sensor set — coolant temperature, oil pressure, intake manifold pressure and temperature, and engine speed pickups — the inputs the ECM uses for fueling and derate decisions.
• ECM to the injector harness — the engine harness feeds the injector sub-harness rather than driving the injectors itself.
• ECM to the actuators — fuel control and air management devices that the ECM commands.
• Engine to the machine side — the link that carries power and ground into the engine circuits.

What a failing Caterpillar 420E harness looks like

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

1. 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.
2. 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.
3. 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.

Where this part sits in the Caterpillar 420E range

ECS lists 2 harnesses in this section group for this machine. At $300.00 the 263-9484 is the most expensive, against a range of $273.90 to $300.00. Stock on hand: 3.

The closest part in price is 308-2266 at $273.90 — $26.10 apart. The two are separate looms; the tag on your old harness settles which one you need.

We photographed this exact unit: 4 images on this page are of the 263-9484 we have in stock, not a catalogue picture. Price tracks section size and how much of the loom is enclosed, not condition — every part we list is new build.

Other harness sections for the Caterpillar 420E

All 4 harness sections for the Caterpillar 420E →

Same type of harness on other machines

• 455-6840 — Caterpillar 315F Engine Wiring Harness
• 296-4617 — Caterpillar 320D Engine Wiring Harness
• 359-1290 — Caterpillar 320E Engine Wiring Harness
• 447-5149 — Caterpillar 320GX Engine Wiring Harness
• 388-4017 — Caterpillar 326F Engine Wiring Harness