Think of your seat belt as an electrical circuit. It’s an ‘open’ circuit when the best is disconnected and ‘closed’ when connected. The seat belt warning light should go out once you have securely buckled up and closed the circuit.
If the seat belt light stays on, possibly along with an annoying warning chime even after you have securely buckled the belt, the circuit is remaining open keeping the warning system active.
You may need to seek assistance from a professional (and expensive) vehicle engineer in order to diagnose and repair the fault. But before you do, here’s a couple of simple things to try based on the most common reasons for the seat belt warning light staying on.
As already mentioned, the seat belt warning system is an electrical circuit that is remaining open and triggering the warning. One common place where this circuit is broken is under the seat.
Airbag and SRS System
Located under the drivers seat, or sometimes the passenger seat on certain vehicles is the airbag and SRS (supplemental restraint system) unit. This system is tied in with your seat belt, along with the passenger occupancy sensor on the seat.
The connections to this unit can often become lose over time, particularly if you are constantly moving the seat backwards and forwards. Take a look under driver or passenger seat for wires and connections. Give all of the connectors a push to ensure they’re firmly in place.
Seat Belt Buckle
The problem might be related to a switch inside the buckle. General wear-and-tear, grime, crumbs of food and anything else you might think of can end up falling into the slot on a seat belt buckle.
Purchase some electric contact cleaner and spray into the seat belt buckle. Connect and disconnect the seat belt a few times to see if this has done the job.
Seat Belt Warning Light and the MOT
The seat belt warning light refusing to go out even when buckled up should not fail an MOT. In order to pass an MOT though, it’s important to ensure that all seat belts are in good working order and that they are free from rips, tears and any signs of wear-and-tear. Other dashboard warning lights (related to the seat belt) that remain on due to a fault such as airbag or SRS will fail an MOT test.