Komatsu 56-7 A/C Wiring Harness

Part number reference for the 51550-19051

This harness is one part sold under one number. Suppliers and parts books write it differently — you may see it as 51550-19051, 5155019051. 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 Komatsu 56-7

It runs from the cab HVAC unit to the compressor and the pressure switches, through the cab wall.

What it connects

• Switch panel to the compressor clutch — the command that engages the compressor.
• Pressure switches to the control unit — the protection inputs that stop the compressor.

What a failing Komatsu 56-7 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.

Other harness sections for the Komatsu 56-7

All 3 harness sections for the Komatsu 56-7 →