Replacing the Gemel alarm/immobilizer/central lock unit

NOTE TO THE READER: 

THIS VERSION IS UPDATED ON MARCH 15TH 2021 AND THIS REPLACES ALL THE EARLIER VERSIONS. UPDATES ON THE SCHEMATICS WERE DONE AFTER THE FIRST RELEASE. 

UPDATE ON DEC 2TH 2022: A SIMPLER SCHEMATICS ADDED FOR THE PERSONS WHO DO NOT NEED BIKE FOUR WAY FLASHER TO REGISTER THE COMMANDS OF THE FOB.

This project started by accident in the spring of 2021. My winter was pretty busy with my regular work projects. (Yes, yes I am officially retired sice beginning of 2019, but what can you do when your old clients call and ask for assistance in their bakery projects...)

My original bucket list for this winter was really short. Just to replace the SmarTire tire pressure display unit in my upper dash. The famous LT-guru John Zeiler happened to have two new sets of the nowadays discontinued SmarTire motorcycle sets and he was kind enough to sell them to me. Replacing the display was an easy job and I had it done already in the beginning of November last year. 

Here I was still happy and putting the bike together just 20 minutes before I realized: "Houston, we have a problem..."

When putting the bike back together I realized that some of my added electrical gadgets did not work. And on top of this one of the bike's original 7,5 A fuses went off when I tried to connect my "master switch" for Ari's added electricals. 

Now this was not fun at all!

I just had to start stripping the bike all over again...

At some point I realized that my remote controller for the central locking and immobilizer was not working. I changed the battery in the fob but no success.

OK, looked like my Gemel (DWA5) unit was dead. ( About an hour later I realized the reason for this but that is another story.) The main thing was that my unit did not work. I was not concerned about the immobilizer or the alarm features since I have my own devices to make the life of a potential bike thief miserable. But I had lost the central locking!

So, following morning I sent email to our local BMW dealer and asked if they would have new units available. After two hours came the answer: No units in central warehouse in Sweden, nor any at the factory in Germany. But these units can still be ordered, price is 426 euros and delivery time is "several weeks". Ok, I could have tolerated the price but not the unknown delivery time.

My next task was then to look for instructions for removing the unit. There are plenty of them available when you just write "removing alarm K 1200 LT" in the Google. Here is one from Kirk Johnson.

BUT: When you remove the alarm unit from your facelift LT, you will also lose your central lock system! Not that it is one of the best ones with very limited range, but it still saves you from running around the bike and locking all the bags when parking the bike. So I wanted the central lock system must be maintained!

So I started figuring that there are still all the lock solenids in place so we just need a command unit for them. My first Google searches took me to the Chinese suppliers but this time I was not too keen in waiting 4-6 weeks for the package to arrive. Then I found this site from Finland.

I called them and checked that they indeed have them in stock and they said they will ship the next day. OK, the price was under 30 euros with postage. Reasonable. The gadget is still pobably produced in China (judging from the price.)

Here is one English speaking site which I found by typing the unit name "Bene 102A" in the Google search

While waiting for the unit to arrive I studied the schematics. 

I realized that it is the page 8 schematics of the manual that will work in LT. The polarity of feeding the solenoid / motors need to be changed when locking or unlocking the bags.

The original BMW unit also flashes the turn signals when you hit the fob. I consulted John Zeiler and he gave me some valuable hints so I was able to reproduce that feature with the Bene unit as well. But only with help of two additional relays plus one diode.  

In the following pages I try to give you as good advise as possible for carrying out a similar project. 

DISCLAIMER: You need some basic understanding about (bike) electrics and preferably ability to solder wires and of course you must know the anatomy of your LT so that you can remove the trunk and the cover underneath it. You also need two extra 12 V basic relays, one normally open (NO) and one normally closed (NC) type for the 4-way blinker function (optional). I use the Wehrle mini relays (to save space as I have about 50 of them spread all over the bike) but any regular 12 V auto relays work. Plus you need also one diode to isolate a two-way feed to the bike system. The tools that you need besides the soldering gun and solder are: Hot air blower for the shrink tubes, wire cutter, wire stripper, some zip ties, velcro for fastening the unit (or you can also use screws through the plastic). You can also use the "Abiko" type of connectors as well but there will be quite a few connections needed and some of them include up to five cables to be connected together. So I recommend soldering and covering the joints with shrink tube.

1. To start with follow the instructions of Kirk Johnsons video until he wants you to make the two jumps between pins #3 and 11 and the other jump between pins # 10 + 6 +2. STOP HERE, DONT MAKE THE JUMPS YET.

2. When you have the old BMW Gemel alarm unit in your hands, cut all the wires from it. You will need the connectors, so don't throw them away!

 You will need all the connectors except the one for the "tilt sensor" which you can throw avay. So you will have one 12-pin, connector, one 3-pin connector (bringing the power), and three 2-pin connetors (for the side cases and trunk solenoids). The glove box solenoid is powered through the 12-pin connector. 

3. Here is the new unit and its very long connecting cables straight from the package. Enough for seven installations at least...Note the fuse in the power cable and the antenna which hopefully improves the range of the fobs. 

This was my testing phase...

At first I was planning to use the original steel bracket but this compartment of my bike is so occupied by one air compressor and some 10 other relays and numerous connectors that I decided to throw the bracket away. There comes a double sided piece of tape with the Bene set but I preferred to use Velcro as the installation is less permanent with it.

4. Here the steel bracket is gone and the Bene is fastened with Velcro on the plastic surface of the rear compartment. You can see the three pin (power) connector next to the new unit. (Please ignore all the other relays and connectors is this and other pictures.)

I also covered the quite big opening above the Bene connector with Gorilla Tape. This is by no means a waterproof protection but will prevent regular dust & junk entering inside the unit. I was also considering sealing the whole unit waterproof with silicone, but since I never use pressure washer on my bike and the rear compartment stays relatively dry, I skipped that.

As you can see in some connections you need to collect a lot of wires. In the center there is the 3-pin connector and the continuous +12V connection is already done (with red, blue etc wires) and the grounding bundle is waiting for the solder and shrink tube to cover. In my earlier version the green switched power wire was unused but later I learned that this wire is needed. So do not cut it!

5. Here is the schematics of how the Bene 102 A is hooked up to bike connectors. I did some careful experimenting and found a safe way to enable the 4-way flashing feature when switching on or off the central lock. Thats why the 2 relays are added. If you don't want this feature, you can leave the relays out and also all the wiring plus diode that is connected to it plus the connection to pin #2 in the 12-pin connector. If you want to have a better printable schematics in PDF format send me an email and you will get one in return.

Some notes: 

The bike 3-pin connector brings continuous power, grounding and switched power. Even if the OEM alarm continuous 12V power feed is protected by a 15 A fuse (fuse #10 in bikes fuse box #2) I recommed that you use the 10 A fuse that comes with Bene AND install it under your rear seat instead of leaving it in the rear compartment. Much easier access to the fuse in case it ever blows...I stripped the bike original wire harness up to the bike fuse box level and connected the new fuse before the bike 3-pin connector (as shown in the schematics.) This was in order to avoid the double cables going back and forth to the rear compartment. I did this because I have about 15 other cables on the same route just to avoid the installation getting too tight.

Here are some other fuses as well under the pillion seat. The one for Bene is the cleanest looking... 

On the 12-pin connector you make two jumps: Pins # 3 and 11. The second jump between pins # 6 and 10. Pins 1 and 12 are used for bringing the power to the glove box solenoid. Pin # 2 brings power to the bike flasher unit and pin # 7 is used for bringing intermittent ground when doing the 4-way flashing with the Bene. But this same grounding has to be cut when the bike ignition is cut, otherwise the four way blinkers stay on continuously. (That is why the NC relay is needed.) With this installation there will be only three wires left over of this connector which you can just cut and leave them (isolated for security's sake) in place. 

When connecting the 2-pin connetors to the Bene unit, make sure they are all connected identically. The Bene blue cable hooks up to to the red/white wire of the solenoid cables and the Bene white cable hooks up to the brown/white wire of the solenoid cable. This way your new fob works logically. 

Here I was connecting the first additional (normally open NO) relay for enabling the 4-way blinkers. 

This picture shows how I connected the diode. In this picture the diode prevents the current flow from right to left but allows it from left to right.

Here the same diode and wire connections were covered with shrink tube

The completed installation. (The sticker on the Bene unit is scratched since I was looking for a hidden screw as wanted to open the unit and see what it had eaten. There was no screw. The unit cover opens from the bottom side by simply spreading it open with a thin screwdriver.)

Here the rear compartment cover was going back in place. You can also see my little Thomas air compressor which is fastened on the lid. Luckily the Euro bikes do not have the famous canister that the US bikes have filling this otherwise very useful compartment!

All done! Just the top box to be installed...(If you are wondering the brackets, they ar for relocating the trunk additional 30 mm backwards from the factory rearmost position. There is a separate story about it in this blog.)

And here is finally the proof of how it works, One flash is locked, two flashes unlocked!

Update on Dec 2th 2022:

A simpler schematics if you do not want to have the 4-way flashers to operate and register the commands of the remote control fob.