453 Alarm Fault

Bob S was one of the many people experiencing the alarm on his 453 going off all the time. It’s already a known fault at smart so we know the problem. The problem is the switch.

The switch is pushed in by the bonnet (hood). If the bonnet is removed or tampered with, the alarm sounds. The issue is that the switch isn’t pushed in very far so it is easily activated. The fix that smart worked out is shit. They put paint on the end of the switch and fit the bonnet.

When the bonnet is removed, there is a paint spot where it touches.

Smart decided that the best fix was to just glue a piece of plastic to the inside of the bonnet. It will work but what if you change the panels? You’ll have to fix the new bonnet too.

Bob came up with a better idea that matched exactly what I had in mind. He placed talcum powder on the switch, fitted the bonnet and removed it again.

This showed him how much the switch had moved. In this case, the switch moved 3mm. However, the switch had far more available travel so…

…Bob created a plastic cap to go over the end of the switch to increase the length and the amount it is pushed.

He turned it from a plastic rod but if you have a 3D printer, you could print one. The hole in the end is 6.3mm. I would make the hole 4mm deep and the cap 8mm long. That will increase the throw of the switch to about 7mm and will stop the alarm going off all the time.

Clean up the switch and push the new cap on. If it’s not a secure fit, glue it into the shaft.

Alternative Fix

One smart centre came up with a nice idea. They used a common smart fixing called a plastic rivet.

Using the previous paint method, the point is marked and drilled. The plastic rivet is push into place.

You can buy these cheaply from eBay. Just search for plastic rivets.