Firstly the replacement part took some finding. For the S54's for some reason the parts are not listed on the BMW EPC. I ended up looking up a 3.0i 2002 for the parts. The original part number was 61 31 8 352 229 but this has been superseded a couple of times so the actual part number is 61 31 9 119 052. Please note this number is for a 2002 ///M Roadster and may be different for other models. I have found that it's worth being cheeky with the BMW parts department, if you ask they usually give a little discount. Mine cost £5.86 + VAT.
So to replace the bonnet alarm switch you need to get the old one out first, it's located at the front of the engine bay, just to the right of the radiator.
To remove it is the tricky bit, either side of the switch are tabs and these need to be pressed in to allow the switch to be removed. The one on the engine side is relatively easy, however the one to the front needed a large screwdriver slipping down the side to push the tab in, as my fingers could not reach.
This is the tab you need to press.....
The switch comes out upwards through the hole
You can undo the plug connector, again the a little tab you need to lift. Use a small flat blade screwdriver but be careful not to lift too much as you could snap it off.
One remedy I tried was to add some pads to the underside of the bonnet where the switch touches. Here there's a small round black plastic pad, I added some self adhesive pads to increase the thickness. This worked for a while but ultimately failed.
I hope this helps anyone with the same problem.
