Ol_Smith
G'day everyone.
I just recently got my first car-1994 Volvo 940 Wagon. I love it, but its had its fair share of problems. Its latest one is the central locking. It was working fine until last night. I deliver pizzas, so constantly lock and unlock the doors on both the drivers and passenger side. It used to be that drivers side would unlock all, and passenger side would just unlock passenger. Now each side just opens its own lock, and the back doors won't unlock at all. Is there anything I/anyone here can help me out with to save me another trip to the mechanic? Will pay for service in beers.
Cheers.
Oli.
jamesinc
Where you at Oli?
jamesinc
First and foremost, check the fuse for the central locking. Might have blown. 50 cent repair job.
If it's not blown, read on.
The way central locking works in the 940s is as follows: there's a small actuator motor in each door that pops the locks up and down. It's down the bottom of the door, straight down from where the lock is. The driver's door is different. It has what looks like an actuator, but actually it's just the shell, and there's no motor inside. So the driver's lock will never move by itself, it always has to be moved by you pulling on the lock or turning the key in the door. Instead, inside the actuator shell, it has a little sensor that trips when the lock is pulled up or pushed down, and this triggers the central locking circuit.
So if the system is working 100%, the driver's door will trigger central locking, but the passenger door won't.
It's very unlikely that all your actuators broke at once, so the problem is either with the sensor in the driver's door, or with the relay. You'll need to take the door card off, or get someone who knows how. It's not very hard once you have seen it done, and doesn't require much in the way of tools. Once you have access to the inside of the driver's door, you can remove the actuator and open it up and check the contacts inside for dirt or corrosion. At this point you could also get a length of wire and short the contacts on the plug, to see if this trips the central locking. If it does, you know the problem is the actuator. If nothing happens, you know it must be something else (probably the relay). The relay is something that you can service, but again if you're new to the whole pulling stuff apart game, it might be a tall order. It's located behind the fuses somewhere (not sure which one it is). Basically inside the relay's enclosure are some small electromechanical parts. When the actuator sensor is tripped, it causes a metal tab to move and hit a contact, which supplies power to the rest of the system. That's the clicking noise you hear (same as with the indicator lights - the clicking is from the relay). What happens sometimes is that the solder holding the contacts in the relay breaks, and contact is lost. To repair, you 're-flow' the solder; that is, you heat it up to melt it and cause it to bond to the contact again.
Hope that helps.
Ol_Smith
Oke doke. Thankyou James, thats alot of helpful info!
Firstly, I'm in Melbourne.
Second-before I go Midnight Spares on the doors and whatnot, how can I check to see if the fuse has blown or not? Once I check that out, I'll start working down your list haha. Cheers bud.
jamesinc
The fuse box is behind the ashtray in front of the gear selector. You open the ash tray, then push the metal tab bit down and it pops out. On the back of the ashtray is a sticker indicating which fuse does what. Use that to determine which fuse to check. Once you know which, you just pull it out (it might be tight, but there should be a little set of plastic tweezers hidden behind there to help you with it. Once it's out, you'll be able to look through it. If you see a break in the wire, it's blown.
Ol_Smith
Update-it unfortunately wasn't a fuse (well, as far as I can tell). I'll start working down your list, but I'm a bit new to/slow with cars so I will most likely be checking back here with you in the near future. Thanks for your help James, I'll let you know how it goes!
jamesinc
Prior to it failing, did it work 100%? As in, did it work, every time, both locking and unlocking the driver's door?
Vee_Que
Where in Melbourne? There are a few of us on here that could help.
Ol_Smith
New update! It miraculously fixed itself. After fiddling with the fuses, I could hear it trying but failing to do something. Then all of a sudden it began working again! :D Thankyou James and Vee_Que for your offerings and advice! I'll be sure to post in this thread again if it plays up, but here's to hoping it won't! Thanks again everyone!
Major Ledfoot
Just fixed the central locking in The Cleever. It was the relay.
JFTR, this thread is one of the first results to show on a Google search for the issue.
