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240 Keyless Entry


New member
Jun 12, 2004
This is an extremely easy job to undertake on the 240, every wire is color-coded for clarity and *should* match up to your alarm brain. This guide specifically references the Audiovox Prestige AA925 BGAAL10R Brain, which can be found on eBay for ~$35 shipped. Your brain may differ, please reference your instruction manual regarding wiring.

Door Solenoid:
First order of business is installing a solenoid into the drivers' door. You don't want a remote that opens up EVERY door except the drivers' door, do you? I didn't think so. Pick up a solenoid from any other door/hatch from another 240. The bracket on the solenoid flips around so that the same unit can be used in ANY location.

Here's what it looks like installed:

Next up is making the linkage so that the solenoid works the locks. I used a wire hangar for this, but if you're at the junkyard scavenging solenoids, grab the rods as well. I had a solenoid from a tailgate but no link rods, so I had to improvise. When you're done, it should look something like this:


Because I didn't have the stock linkage rods, I had to drill a hole in this piece:

This works fairly well but I'd like to strongly reiterate that it would be MUCH easier to use the linkage rods that volvo supplies. EDIT: the front passenger door linkage works great here. It's not perfect but it's MUCH easier than drilling and bending coat hangar rod.

Next up, wiring. The door solenoid has blue and yellow wires. If you look at the wires coming from the key and lock pin switches, they are ALSO blue and yellow. However, you can't use these because they are signal lines to the relays, not the actuation lines. So you'll have to extend the wires from the solenoid into the cabin and behind the middle heater vents (where the relays reside).

I ran mine along the inner door harness and fished them through above the fuse box, like so:


Wiring the Alarm Brain:
The Volvo 240 is a negative (-) pulse lock and unlock system. The relays for the door locks are located behind the center console, up behind where the coin tray would be and almost right underneath the vents. #188 and #189 in this picture:

After you fish those out, find the wire sheath that brings a green and a red wire to the relays. These are your signal wires. Connect your negative unlock pulse wire to the green, and the negative lock pulse wire to the red. IMPORTANT! If you connect your signal wires from your brain to the WRONG wires, you WILL FRY YOUR ALARM BRAIN. See wiring diagram below - there's another green wire that supplies 12v constant to both relays, do NOT connect your signal lines to this wire!

Then find the blue and yellow wires going from the relays into another sheath and connect the wires from your drivers' door solenoid.

Here's a modified greenbook diagram:

After everything is connected, you should be done! Wasn't that easy?!? For less than $50 including the JY cost of the solenoid/rods and alarm, you now have keyless entry. Enjoy!
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Hi Richard

I'm about to do this in my 744. I'll post back with a scan of the wiring diagram for the 744 door lock relay.
Great easy modification. It's on my list . . . as soon as I get it running.

I assume that this unit also requires the remote transmitters. So about $70-80 for all door lock/unlock system. Not bad.
Great easy modification. It's on my list . . . as soon as I get it running.

I assume that this unit also requires the remote transmitters. So about $70-80 for all door lock/unlock system. Not bad.

You can buy a keyless entry kit from autozone for about $50, includes the module, 2 remotes, and pretty detailed instructions if you care to add an immobilizer/remote trunk release.
Yeah, if your car has the actuators to open the trunk, it can be made to work that too. Just tie the unlock/lock wires just like the diagram shows.

I tested this in my 744 and it works fantastic, no relays needed to open the locks. Just need to buy an actuator, and tie that back into the factory relay circuit and she'll be rollin.
GREAT thread, easy to read and understand. Really thinking about doing this know that I have my 240 back on the road, finally got around to fixing my power locks after six years of owning the car.

Thanks for posting, surprised this thread didn't get more interest back last year when it was written!
Good info. I'm using this info to install the solenoid on mine at the moment.............
Where are my relays?

Nevermind! Found them. Small and behind the mounting bracket but they were there.

I am doing this remote lock conversion and do not find the relays as indicated in the first post. Mine is an '82 Diesel (245). My dash is as pictured but no relays as indicated. I have never found a wiring book for the '82 assuming that the one for the '81 has always worked.

Anyone know where my relays are? I guess I could connect the battery back up and listen for relay operation but with three actuators operating at the same time and the fact that I don't hear as good as I once did might make that a little difficult.

Great idea though! I didn't want an alarm system and therefore found a remote unit with two fobs and the receiver control box for $12 and got the Volvo lock activator from RedwoodChair for $20. It came with the lock connection rod and cutting it off to match the driver door system with the knob switch took about 5 minutes, most of which was staring at it to make sure I cut it right the first time.

A fully wired remote door lock system for $32. Such a deal!
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Old topic, but i can't find anything about wiring in the indicator lights to a central door locking system. I just installed mine using this tutorial (it was really easy) but my receiver unit also has a wire for the indiciators. They flash once on locking, twice on unlocking. What is the easiest way to connect those? I guess the easiest way is to splice them in right after the indicator relays? But where is this relay? I tries to locate it by listening and it looks like it is somewhere near the pedals, but I am not sure..
If your alarm brain already has a relay on board for flashing the parking lights (as most do- it will show +12v output), then you just identify the parking lamp circuit for your year and model and make a single connection.

Should take you 5 minutes with a test light.
Indeed. The alarm brain does have a relay and it was just a matter of wiring this to the indicator circuit. After looking at the diagrams I figured the easiest way was to splice them in right after the emergency light switch. If you take this out of the dash and remove the plug on the back the pins are numbered. The ones that say "L" and "R" correspond to the lift and right indicator circuits (what a surprise!). Splice the wires in behind the plug and solder the wires from the brain to them and you're done. Easy!
Just install remote central locking. Thanks for the guide , it is perffect !

Remote central locking kit I bought for 12 EUR (~14 $) and 3 EUR for door solenoid.

Just wanted to add pictures about conecting indicator lights. I have keyless kit brain with two wires for indicator lights. One for left side and one for right side, if you have just one wire , then you will need relay.

First of all I was little suprised that volvo use 1 relay for both sides, I thought there will be two. (See in picture below, I marked it with orange box). From time relay , wire goes back to hazard light switch via indicator switch at steering wheel. So after the hazard light switch I just conect left side wire to the green wire and right side wire to the blue wire (see pictre below).

If your keyless kit brain have only one wire for indicator lights, then you have to use relay (see the last picture), because if you just connect blue and green wires with keyless kit brain indicator wire, each time you will switch indicators, both sides will blink.


To simplify the wiring and disassembly, below are some tips. The universal keyless entry system that I used was purchased from the jungle website, search for B01F2SWX2C. The remotes are tiny and seem well constructed, only $13 at the time.

Wires from the universal keyless ECU brain box (your colors may vary) -> connection to car wiring:
1) red -> fuse box +12v constant (open lug on hazard light fuse #9)
2) black -> ground
3) white -> door switch harness red wire (lock)
4) white/black -> door switch harness green (unlock)
5) yellow -> ground
6) yellow/black -> ground

There's really no need to access the door lock relays behind the center stack, all the wiring tapping points can be made at much easier locations. Furthermore if you do decide to dig out the relays, the wiring is very short and packed tightly behind the IP. The lock/unlock signal wires (#3 red and #4 green from above) can be accessed under the steering wheel by removing the undercover and/or knee bolster. The output wires for the door lock actuators (blue & yellow) are easily accessible behind the glove box. Photos below show these locations.

Finally, please don't use those crimp-type splicing taps. They destroy the vehicle's wiring & insulation. There's a product called Posi-Tap that are so much easier to use/reuse and friendlier to wiring. They aren't cheap but totally worth it. Get the 14-18 gauge blue ones for our wiring.

This is location of door locking relays:

See how tight the wiring is tucked? Don't even go there...

Underneath the steering wheel the red & green relay input signal wires can be found:


And the blue & yellow lock actuator output wires can be found behind the glove box: