Car MOT Manual 2012 onwards
1.9 Electrical Wiring and Battery
InformationThis inspection applies to all vehicles, including electric and hybrid vehicles.
Some tow bar electrical sockets are hidden behind an access panel in the bumper or bodywork. Unless requiring the use of tools or specialist equipment, these panels must be removed to facilitate the inspection of the towbar socket.
If a tow ball or pin is not fitted at the time of test, e.g. because it is detachable, has been unbolted or otherwise removed, but the attachment brackets are still in place, any trailer electrical socket should still be assessed.
This does not apply if the attachment brackets have been deliberately rendered unfit for further use
Method of Inspection1. Check the condition and security of the batteryies.
2. Check the condition and security of all visible electrical wiring.
3. On vehicles fitted with a towbar, check the condition and security of the trailer electrical socket.
Note: This check applies to both 7 pin 12N and 13 pin electrical sockets.
4. On vehicles fitted with a trailer 13 pin Eurosocket, use an approved device to check that the socket is wired to correctly operate the trailer:
• Position lamps
• Stop lamps
• Direction indicators
• Rear fog lamp
Reason for Rejection1. A battery insecure or leaking electrolyte.
2. Electrical wiring:
a. insecure or inadequately supported so that it is likely to become damaged
b. damaged or deteriorated to the extent that it is likely to cause a short circuit or become detached
c. insulation damaged or deteriorated to the extent that bare wiring or connectors are exposed.
3. A trailer electrical socket: a. insecure
b. damaged or deteriorated to the extent that the connecting lead could not be securely connected.
4. A trailer 13 pin Euro-socket not operating the trailer lamps as intended.