cross-ref, equivalent part, alternate part, form-fit-function equivalent, drop-in replacement
Cross-referencing connectivity parts is harder than cross-referencing a resistor, because a connector is a system rather than a component. To be a genuine drop-in, an alternative has to match on more than a datasheet headline.
It has to mate with the same counterpart, which means the same interface geometry, the same keying and the same coding. It has to accept the same terminals, or the terminals it accepts have to be sourceable and crimpable with the tooling already on the floor, at a crimp height the applicator can produce. It has to take the same wire seals for the insulation diameter in use. It has to carry the same environmental rating and, on a qualified programme, the same test standard. It has to match on plating, because tin and gold are not alternatives to each other. And it has to be acceptable to the buyer's approval process, which is a separate question from whether it works.
Miss any one of those and the part is not a drop-in. It is a change, and a change has a cost: a tooling change, a validation, a drawing revision, or a matching change on the other end of the connection.
That is why a bare cross-reference table is close to useless in a shortage. What a buyer can act on is a proposed alternative with the differences stated: what matches, what does not, and what has to be checked or approved before it is used.
Harness Code proposes alternatives in that form. Where a direct match exists, it is offered as a direct match. Where it does not, the functional differences are written down rather than glossed over, so the decision stays with the person who owns the drawing.
Related terms
Manufacturer Part Number (MPN)
A Manufacturer Part Number (MPN) is the unique code a component maker assigns to one exact product variant. In automotive connectivity, the MPN fixes housing, cavity count, keying, colour and plating, so two parts with different MPNs are not interchangeable even if they look identical.
Second source
A second source is an approved alternative supplier or manufacturer for a part, qualified in advance so production can switch without a redesign. Single-sourced parts are the ones that stop a line when their single source fails.
Contact plating (tin vs gold)
Contact plating is the metal coating on a terminal's mating surface, most often tin or gold. Plating decides contact resistance, corrosion behaviour and how many mating cycles a contact survives. Tin and gold contacts should not be mated to each other.
Crimp and crimp height
A crimp is the cold-formed mechanical and electrical joint between a terminal and a wire. Crimp height is the measured height of the finished conductor crimp, and it is the main control on whether that joint survives vibration and temperature cycling in service.