S40 - 05, Trunk won't open!
 

Hi all!

A week ago my trunk suddenly would't open any more. After cursing a bit I went to Google for help, and seems as Im not the only one out there with this problem. People apparently fixed this by replacing the trunk handle module (don't know the word, sorry, not native english :)) that's holding the trunk handle and license plate lights.

So went to my local Volvo dealer and got spare parts for a new handle + new lights just for the sake of it.

Sadly though, this didn't fix the issue with my trunk but the new license plate lights are much better than the old ones :)

So yesterday after reading about more drastic measures, I crawed into the trunk via the back seats and started dismounting the lining in the trunk to expose the wiring, and also to try to remove the lock just to be able to open it and perhaps find something wrong with the locking system. Anyway, behind the lining were three screws holding the lock to the trunk. I removed those and that made the trunk able to open just a little little bit. I also saw two bigger screws behind the grey plastic cover, pressumably holding the other part of the lock into the chassie itself. However, I didn't dare to remove these two screws, because Im afraid I'll loose them behind the plastic cover which I didn't manage to remove.

Anyone here with the experince to have removed the trunk locking system that could point me in the right direction or correct me if I did something wrong?

Please take a look at the attachments for more detailed information about what I mean. :)

One more thing...refer to attachment 1 when I ask if there is a way to "hotwire" that connector (that goes to the trunk handle module I spoke about) to simulate a person pressing the trunk handle. I know this is possible when it comes to computers loosing the on/off switch :)

Regards
Gustav

It's almost never the handle. for some reason it's often suggested as the cause but it almost never is. First port of call is the wiring. It's a common fault that the wiring fails inside the flexible rubber conduit that joins between the boot lid and the body.

Regarding your present situation. you should be able to just disconnect the connector that's connected to the lock mechanism and open the lid, leaving the lock mechanism locked to the body of the car. once you have access to the mechanism you can manually open it (that is, without electricity). It's been a couple of years since I replaced my lock but there's a small lever towards the electrical connector end of the lock. you can manipulate that with a screwdriver and it will unlatch. As I said, I don't remember exactly but just poke around with a screwdriver (DON'T force anything though).

You can trigger it electrically by applying 12v to pins 1 & 2 on the lock connector (the left two pins as you look at it in the second image you provide, don't apply the voltage whilst the connector is plugged in to the rest of the car in case you make a bad connection. you can't trigger it from the grey connector on its own due to the way it's wired, only one conductor goes directly to the release motor, the other comes from the switch unit.

Once you've git it open check the wiring between pin 1 on the lock connector and pin 4 on the grey connector... they should be connected. if they aren't. that's your problem.

Thank you very much!

I went to my Volvo dealer again yesterday and ordered a new wiring harness! So, when that arrive tomorrow (hopefully) I can just disconnect the current and wire up the new one just temporarily to the lock and to the trunk handle.

If it's the current wiring harness that's broken, the trunk will pop open without disassembly the lock at all!

If it turns out not be the wiring, I think it's out of my comfort and knowledge zone to go any further and will need to hand it over to the dealer.

Thanks again!

Tried to send you a private message, but not allowed as fresh member :(

Just a quick question. What do you suggest is the easiest way to apply 12V manually to the lock? Just via a battery connected with two small wires? Any risk to "blow up" or short circuit the lock by doing this?

Thing is, if I get it open before the wiring harness arrives, I can determine if it indeed is the wiring that's faulty. If it's not, then I don't need to get the part from the dealer.

There's nothing in the lock that you can break just by trying, there's two electrical components inside the lock, one is the solenoid which actuates the lock, a solenoid is just a fancy coil of wire if you connect this the wrong way all that will happen is it will attempt to drive the mechanism the wrong way and it will not open, this will not cause damage, I've done it to my own lock on the workbench. The other component is a switch. If you accidentally short through this, again, not much will happen, you may get a spark when making contact there'll be no damage done. The switch is dual purpose, when locked it signals to the car that the boot is closed. when open, it powers the interior light.

I don't know for sure, but it will probably actuate with only 9v from a small 9v square battery, I don't know for sure but it probably has enough juice to drive it. Just some wires from your power source is fine enough. Just remember to do this directly at the lock terminals and ensure you aren't feeding current into the rest of the car in case you apply voltage somewhere you shouldn't.

Terminal pin 1: Source/12v( perhaps 9v )
Terminal pin 2: Ground/0v

EDIT: terminal designation

Snoodini, thanks again! I think I will give it a go tonight :)

I found these batteries in the shop. Very surprised that they are cranked up to 12V, but these should work...?

http://www.clasohlson.com/se/Alkalis...-V23GA/22-3226
http://www.clasohlson.com/se/Alkalis...a-V27A/36-5217

Then just a wire from the battery's + pole to pin 2 and - pole to pin 1 to the lock terminal?

Sorry if Im being stupid... (not much of an electrician, should maybe what for the replacement wiring harness :))

Either of these should be fine. I had no idea those batteries existed! and for 50kr it's probably worth a shot. If you have a multimeter i'd check the wire i mentioned if you can.

I'm 95% confident that your problem is the harness though.

I don't know if you've seen it but I did write a guide for replacement, although you've already completed most of the steps already! here

oh, and I corrected my post regarding the polarity of the connector as I think I had it wrong. but it will not hurt to try either polarity, simply one way will work, the other won't

Yes very well aware of that awesome guide! In fact it's from that I found inspiration to make this a DIY job! Didn't realise you wrote it until now...

What post did you correct? Can't find it :)