cable clamp, strain relief, wire dress cover, boot, conduit adapter
A crimped terminal is strong in tension along the wire and weak against everything else. Pull the bundle sideways, let it hang unsupported, or let it vibrate against a bracket, and the load travels down the wire into the insulation crimp, then into the conductor crimp, and the joint eventually opens. The backshell exists so that load never reaches the terminal.
It does three things. It clamps the wire bundle to the connector body, so tension and vibration are carried by the housing and its mounting. It sets the exit direction, commonly straight, 90 degrees or 45 degrees, which lets a harness leave the connector in the direction the routing actually needs instead of bending hard against the seal. And on sealed or shielded connectors it closes the rear of the assembly, interfacing with conduit, a rubber boot, heat-shrink or a braided shield.
For procurement this is another accessory that behaves like a required part. A backshell is family-specific, often exit-angle-specific and cable-diameter-specific, so one housing can have half a dozen valid backshell references of which exactly one is on the drawing. It carries its own MPN and its own lead time, with no relationship to the availability of the housing it fits.
The recurring failure is a build that is complete on housings, terminals and seals and blocked on a 90 degree backshell for one branch, ordered late because nobody read it as a critical part.
Harness Code sources connector accessories, backshells, boots, conduit adapters and clips as part of the connector set, and confirms exit angle and cable-diameter range on anything it proposes.
Related terms
Connector housing
A connector housing is the moulded plastic body that holds and positions the terminals of an automotive connector. It is sold separately from the terminals and seals it accepts, so a working connection is always a matched set of housing, terminal and seal, not a single part number.
Sealed vs unsealed connector
A sealed connector uses interface seals, wire seals and cavity plugs to keep moisture and dust out, and carries an IP rating such as IP67 or IP69K. An unsealed connector has no such protection and is used only in dry interior locations.
Approved Vendor List (AVL) / Bill of Materials (BOM)
A Bill of Materials (BOM) is the complete list of parts and quantities needed to build a product. An Approved Vendor List (AVL) names the manufacturers and suppliers a buyer is permitted to source those parts from. The BOM says what; the AVL says from whom.