That bonnet switch!
 

Hi, I have searched the forum and although many posts about this can't find a specific answer to help me, I have a 2013 S80 and have the bonnet open light on permanently and the alarm sounding randomly. After some reading I believe I can short out the bonnet switch which will stop this from happening. I have seen a black plug sat adjacent to the headlamp unit (right side when sitting in the seats), it has two wires in and two out. Is this the plug and is it just a case of joining the two wires together?

Whilst I can't answer your direct Q, I have had the same problem, and found that a liberal squirt of ACF50 fixed mine...

I think it was just winter damp and crud that was stopping it working

Been ok since, but I do reapply a squirt of ACF occasionally.

Same applies to the rear door opener - sometimes it sticks, but a wee blast of ACF50 every so often keeps it sweet

Yes, had already tried using WD40 everyday for 4 days and working the bonnet catches to no avail.
Anyway, yesterday I went for it and pulled the plug, checked the voltage and only 1.6 volts feed so put a short across the two pins. Bingo! lights flashed again on locking (wouldn't flash before as it thought the bonnet was open) and the bonnet open indication with warning triangle disappeared! The alarm has not gone off either.
I then cut the two wires on the bonnet side of the plug and crimped them together for a permanent short.
The only downsides are that there will be no warning that I have left the bonnet open but to be fair I had driven for 30 years in cars without a warning and never had a problem and the alarm wouldn't go off if the bonnet is lifted!
These are minor issues considering what Volvo wanted to charge me for the repair.......£150 diagnostic fee to determine the fault (even though I am telling them what it is) and then £144 per hour labour for repairs plus parts.........(they do give you £50 back from diagnostic if you have the repair done, very generous).

I also have the "Bonnet Open" message. I unplugged the twin cable connector on the right side of the car and put a paperclip jumper across the feed and the warning went. So I suppose this is conclusive that the car is not receiving a circuit closed signal from the switch and despite spraying with a lot of WD40 Silicone Spray, it doesn't seem to want to operate. I cannot leave the cable plugged in as the alarm goes off at random. I also have a warning that the alarm needs servicing.. Is the switch easy to DIY change? if it were renewed could I bank on the crisis being over or could the fault be in the alarm as well? Am I taking any risk of damaging the system if I leave the paperclip in place shorting out the switch feed?

In addition to my woes, I have failed for the multiple time to install VIDA on my laptop and cannot carry out any diagnostics. I am going to post a plea for help with the installation but meanwhile I either leave the paperclip in place or take a bulging wallet round to the dealers!:sad_smile:

Hi,

Wrap the paperclip in some electrical tape, this will stop it shorting out,

As above, just be aware that the bonnet sensor system wont tell you if you leave it open...

Vida can be a pain to install, its heavily dependent on having the right version if Internet Explorer installed,

I succeeded in the end by installing it to a clean inside a virtual machine

Rob

Thanks Rob for reminding me that the paperclip could touch some other conductor and cause problems. It wasn't touching anything when left but movement of the car and vibration could move the p[osition of the hanging plug! Thanks.

I have the same issue. Can you explain as if to an idiot where on the car the connector is and if I have to remove anything to access it? I've looked at the image above and compared it to a photo of the engine bay of my car and I can't work out what I'm looking at. Mine is an '07 S80 V8, so it may be that the engine bay is laid out slightly differently.

Edit: OK, I reread the post and then worked out which way the photo in the first post is orientated, so just to confirm, this is where I should be looking? Unfortunately my engine is in the way!

Attachment 112372

Yes the connector is just inboard of the headlight mounting and faces in line with the car. There is a retaining clip on the plug. Pull out the plug and insert a "U" shaped bent paperclip onto the two connector sockets. Insulate the protruding bare metal clip The car then believes that the micro switch is closed. This is only a work-around not a fix.

This advice is based upon my experience with my 2012 XC70 and may not apply to your older S80. However there will be a connector and it will be short circuitable.

Thanks for your help. This worked for me.

there are two latches/locks for /s80 bonnet, I had same problem with alarm going off randomly, open bonnet message etc. A lot of WD40 on both locks helped but it was the left one(as standing in front of car) causing the problem, I think sensor is there.