Caterpillar 330B Electronic Control Box Wiring Harness

Part number reference for the 135-6090

This harness is one part sold under one number. Suppliers and parts books write it differently — you may see it as 135-6090, 1356090 · CA1356090. 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 330B

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 330B 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 330B range

ECS lists 2 harnesses in this section group for this machine. At $450.00 the 135-6090 is the cheapest, against a range of $450.00 to $566.50. Stock on hand: 3.

The closest part in price is 137-6946 at $566.50 — $116.50 apart. The two are separate looms; the tag on your old harness settles which one you need.

We photographed this exact unit: 6 images on this page are of the 135-6090 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 330B

All 16 harness sections for the Caterpillar 330B →

Same type of harness on other machines

• 143-3580 — Caterpillar 140H Control Box Wiring Harness
• 142-5835 — Caterpillar 140H Controller Wiring Harness
• 472-7732 — Caterpillar 320D2 ECM Connector Assembly
• 267-8049 — Caterpillar 365C Main ECU Wiring Harness
• 290-6751 — Caterpillar 420E Engine ECU Wiring Harness