Recently the alarm on my 2010 Focus went off in the early hours. I opened and locked the car to reset. When I drove the car the following day, I saw that the 'Bonnet Open' warning was showing. I checked the bonnet and it was firmly shut, (This was during the very cold weather we had a few weeks ago). I sprayed the metal rod, which I assume activates the bonnet switch, with WD40 and the problem appeared to go away. That was until last night when the alarm went off again. I had to leave the car unlocked overnight as I didn't want to disturb the neighbours any more, (there were already some lights on!). This morning, I started the car and due to me working from home and not using it very often, it only just started, the battery was very low, however, the bonnet open warning was not on.

Please does anyone have any suggestions. It is annoying that I can lock the car and leave it outside the house all day without any problems, then it seems to happen in the middle of the night.

8 hours ago, SPD2211 said:

Recently the alarm on my 2010 Focus went off in the early hours. I opened and locked the car to reset. When I drove the car the following day, I saw that the 'Bonnet Open' warning was showing. I checked the bonnet and it was firmly shut, (This was during the very cold weather we had a few weeks ago). I sprayed the metal rod, which I assume activates the bonnet switch, with WD40 and the problem appeared to go away. That was until last night when the alarm went off again. I had to leave the car unlocked overnight as I didn't want to disturb the neighbours any more, (there were already some lights on!). This morning, I started the car and due to me working from home and not using it very often, it only just started, the battery was very low, however, the bonnet open warning was not on.

Please does anyone have any suggestions. It is annoying that I can lock the car and leave it outside the house all day without any problems, then it seems to happen in the middle of the night.

The micro switch inside the mechanism has likely worn out, I replaced mine the back end of the year with this part of Amazon.  It's been perfect since AND felt much more solid than I expected for the price.

Thank you for replying, I will check the switch. By the way, I left it locked last night and all was OK.

Does anyone know how to disable the bonnet switch. I can live without the 'Bonnet Open' warning.

Unplug it and bridge the plug with a jumper wire.

If you just leave it unplugged it may not lock, and the alarm definitely won't set.

Thank you Tom. So I assume it is probably grounded when the switch is activated.

The bonnet switch is both part of the security system and also the warning light telling you when the bonnet is open. When the bonnet is closed the switch is closed (short-circuit) and when the bonnet is open, the switch is open-circuit. It is wired back to the BCM unit and is not connected to chassis earth. If you what to disable the bonnet switch then you will need to unplug it and then short the two connector pins together (with something like a paperclip), make sure to insulate the connector with tape so that it can't accidently touch earth.

Thank you for the advice. I have just checked the car and the warning is still on. I will try what you suggest.

It's worth pointing out that if you disable any part of the security system it will likely void your insurance. It's probably ok to do this for test purposes but I would advise against leaving it in as a permanent modification.

OK thank you for the advice.

I disconnected mine recently,no problems since tucked the wire away easy 

Thanks for all the advice

On 3/3/2021 at 6:42 PM, FatHead1979 said:

The micro switch inside the mechanism has likely worn out, I replaced mine the back end of the year with this part of Amazon.  It's been perfect since AND felt much more solid than I expected for the price.

I recently started having the same "bonnet reports as open when its not open" problem - I'd done some googling and come to the same conclusion. Checked this forum just in case and wanted to say thanks for the info! Going to order the part tonight.

Just wanted to double check this next bit - from all the guides I've seen, I can just undo the two bolts (1.), pull the old unit back (2.) and it should slide off the lock cylinder end, and then unplug the cable (3.)... then do the reverse to install the new one yes? No need to faff around with the grill/lock cylinder?

As you can see from the photo: the current catch unit is preeeeeetty damn rusted!

Thanks in advance for any help!

Did this work? Currently having the same issue 😩