Surface oxides
All metal surfaces oxidize in contact with air. This makes it important to fit a cable terminal on a stripped cable for crimping as soon as possible after stripping the cable.
Most cable terminals are tin plated. Tin oxidizes rapidly and the surface oxide coating makes a hard layer on the soft tin which cracks easily when a pin or socket is attached to create a contact.
The surface oxide around contact points protect build a gas tight joint which prevents further oxidation and provides a good electrical contact.
Scheme 266
Scheme 267
Scheme 268
The ground points on a car are a vital part of the car electrical system as all sub-system voltage levels have the ground point as a reference (0 V).
The illustrations above shows a ground point screw connection of the type found on the cylinder block (upper illustrations) and to the body (lower illustration). The arrowed lines show the path of the electric current through the contact point.
A poor contact on the ground point will have a negative impact on the car electrical systems. It is therefore very important that the ground point contact is in good order, that the screw is tight and the cable terminal is correctly crimped to the cable.
Especially important are ground points where several wires are connected to one ground point.
Note. There should be no oxidation between the cable terminals and the screw head.
Installation
Always clean around screws, nuts and contact surfaces.
Scheme 269
The secondary locking must always be adjusted to the initial position.
The secondary locking must be closed in reverse order to the way it was opened.
When the secondary locking is closed a "click" is often heard.
If it cannot be closed it might be because the cable terminal is not completely inserted in the cavity.
If the connector has a sheath, cover or rubber gasket for the housings, do not forget to reinstall it.