i have a 1988 760 turbo sedan which the driver and passenger lock cores have both locked up due to either cold weather or use. rather than spending the quoted 1100 dollars for lock parts and replacement, i was wondering if it would be possible to install a keyless entry system of some sort in this car. i took it to two shops, one said that they could do it and another said that this car had "vacuum actuated" door locks and that installing a keyless entry system would be impossible.

so does anyone know if this is possible, and if it is possible, would it also be possible to have such a system work if the lock tumblers no longer rotate?

any input would be happily accepted

I think we should get some facts straight here:

1, No Volvo has ever been fitted from factory with vacuum operated central locking. Anyone who says they have is wrong. Vacuum operated central locking does not work and was only tried on a few cheap cars. I know Saab never used them and I very much doubt Mercedes did.

2, In order for a remote central locking system to work, you do not need your lock barrels to work. It is in fact common in Sweden to remove them all together and just have a remote central locking setup. However, I would not recoomend this as what do you do if the remote system brakes down? Because it will!

3, On the 700 series, Volvo used four motors and one actuator, on the 900 series they used five motors, the driver door one having a built in actuator. Thus, if you have a 700 series and you wish to install a remote central locking system, you need to add a motor to the driver door. To use a Volvo motor is a good idea as it will fit better but it can be from a 700 or a 900 series. This motor will lock and unlock the driver door via the locking rod in the door and thus causing the actuator to lock and unlock the other doors.

If you need any help or further information, e-mail me, I have done this many times on both Saabs and Volvos.
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George Holmer, Belgium, Europe, 1987 745 GLE Turbo Diesel Intercooler (D24TIC/M46) 200k; 1988 745 Turbo Intercooler (B230FT/M46) 290k; 1988 745 GL (B200E/M47) 190k

Originally posted by gholmer:
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I think we should get some facts straight here:

1, No Volvo has ever been fitted from factory with vacuum operated central locking. Anyone who says they have is wrong. Vacuum operated central locking does not work and was only tried on a few cheap cars. I know Saab never used them and I very much doubt Mercedes did.
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Do you count Audi as a cheap car? I know for a fact they used them in the early 80's on their cars. My dad had a 1980 Audi 5000.

Mercedes W123 series cars (240D in early 80's) also had vacuum operated central locking systems.

The system works, but it is not the best method to use for the application.
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MD

Ok, maybe I overstated the case somewhat. It was used in the early 80's also on fairly good cars.

George
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George Holmer, Belgium, Europe, 1987 745 GLE Turbo Diesel Intercooler (D24TIC/M46) 200k; 1988 745 Turbo Intercooler (B230FT/M46) 290k; 1988 745 GL (B200E/M47) 190k

I think I'd be more concerned about fixing the locks, they do tend to get very tight when they are left unlubed for too long, try squirting some high quality penetrating fliud into the key holes, drown them in the stuff, it could loosen them up after a while.
When I got my 760Ti the locks were very stiff, I've sprayed them twice so far and they are getting a lot better, they were tight enough when I got it that they were bending the key a little.

The other thing that I have seen catch quite a few people out is a worn key, what sort of condition is your key in?
Keys do wear out, the metal rubs off them and often they loose enough metal that they no longer operate the door locks, and I have usually found that they stop working in the doors before the ignition. I had one key for an old mazda once that never stoped working in the ignition, but would not open either door.

The only problem with the worn key issue is that you need the original key code to get a new one cut, as most times getting a new copy of the of the old key won't do any good, as there is no longer enough material there to get a good copy.

I believe most Volvo dealerships can make you a fresh key with your VIN#.
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1988 760Tic - 154,000, 1966 M-B 230 sedan - 98,000

European cars like Saab and Mercedes of that year (1988) have vacuum lock systems where hoses route pressure or vacuum to the locks to lock and unlock the doors.

My '88 740 Turbo does not. I don't think yours does either. Anyone, please correct me if I'm wrong.

If both lock cylinders in the doors have failed, but your central locking system works still off the driver's lock knob, you could have a keyless entry system installed.

If the central locking system isn't working in conjunction with the driver's locks, either by key or knob, then the first step is to repair the system. Either the relay behind the fusebox is bad, a fuse may be blown, or both of the switches in the driver's door have failed. If all doors lock and unlock in conjunction with one of these methods, then the other lock switch has failed.
Once the driver's door is apart you will find these switches with the help of a Haynes manual.

After repairing the system, to install a keyless entry system you're best off adding a door lock actuator at the driver's door. It is the only door without one. The lock/unlock triggers of the keyless system splice into the OEM central lock system, and the new driver's actuator gets wired in as well. This is how I've done two cars. Be sure to get the driver's actuator in sync with the lock/unlock pulses, or else you'll just burn it up.

I've got several actuators. If it's the electric system (not vacuum) you can use actuators out of 240s or 740s. If you decide to tackle this yourself feel free to email me directly with questions.

Consider getting the driver's door lock cylinder replaced, as you'll be locked out when the battery is dead.

Now one for the electrical engineers-

When I use the keyless entry system on my '88 745, I see a big current draw when I lock and unlock the doors. The idle will drop and then run back up to normal once the locks cycle- it's only for a second. This does not happen when I hit the highbeams or crank the heater fan. Any thoughts? I wonder if there could be an open feedback situation when the driver's door actuator triggers the OEM switch after functioning off the remote signal.

I don't know for a fact that you need the locks to be functioning for keyless entry to work. You might just need the rods inside the door to be working? I have been told on this board that if you can find a junked 900 series car you take the power lock actuator out of its passenger side door and install it in your drivers side door. The reason for choosing a 900 series lock actuator is that its supposed to be pre-wired and ready for a keyless entry hookup. Hope this helps some.
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1988 760Tic - 154,000, 1966 M-B 230 sedan - 98,000

You've probably been fed some misinformation. In order for remote unlock to work, I think that you need the regular locks to work also. Ok, maybe you don't. But I think it would be a bad idea to try to rig up remote locking without the locks working in the first place. What a remote unlock system does is piggy backs itself onto what the thing that you pull from inside the car to unlock the doors. I don't know what 'vaccuum actuated' door locks means, but there is magnet (doorlock actuator technically i think) that connects to the lock/unlock bar that you can pull from the inside. In my 86 740 gle, all doors have this magnet except the drivers door. That's why when you unlock the car from the drivers door, all the doors unlock. In order for remote unlock to work, you need the driver's door to have the magnet hooked up just like the rest of the doors. There are already mounting holes, u just need a magnet thing from a parts car. When you supply power to the magnet, it will be just like you were unlocking the drivers door from the inside and all the doors will unlock. You hook up the keyless entry so that it supplies power to the newly installed magnet (doorlock actuator) and it works.

If any of this is unclear I'll try to clarify.
-Nathan