remote entry won't arm alarm 92 300E
 

I just installed a remote entry unit in a 1992 300E.

The unit works fine, locks and unlocks all doors and trunk, both with the key or the remote.

When I tested the factory alarm, it works fine when locked by the key, it arms and disarms.

When locked with the remote however, the alarm doesn't arm therefore doesn't work.

The remote module is wired in series at the blue (drivers door lock) wire at the vacuum pump as per instructions and this part of it works properly.

Any help/suggestions appreciated,

Acky

Alarm problem solved.
 

Alarm problem solved.

You can NOT install a remote entry unit in all W124 models as shown elsewhere in this forum.

Only if your car has exactly the same wiring configurations should that method be used, and even then you must test the factory alarm to ensure that it works properly with the remote as well as the key.

When installing the remote control module, you MUST cut the lock/unlock wire going to the vacuum pump that also signals the arm/disarm wire going to the anti theft alarm control unit to arm and disarm, connect the wiring in series at the cut wire.

If you use the wrong wire, remote locking and unlocking will have no affect on the alarm. For example if you lock the car using the key, or the passenger door lock button, then later unlock the car using the remote, the alarm will be activated and you can only stop it by using the key to unlock/disarm.

Also if you lock the car using the remote, if it’s not properly wired, the alarm system will not arm, so it’s useless.

I shudder at the thought of how many W124 models (and others) are out there with botched alarm systems for this and other reasons.

Acky

This post is a moot point for Acky since he's figured it out, but basically, the alarm configuration on W124 era cars is such that the alarm is not connected to the lock mechanism or the lock buttons, but to the key cylinder. There are micro switches inside the cylinder assembly which arms/disarms the alarm.

One further note re: the key cylinders - that are NOT interchangable from left to right.

Acky,

I'm the guy who posted the original instructions on this. My guess is that there have been in excess of 200 installations. I've had maybe 5 people contact me with problems on the install, and as far as I know, all were able to solve the problem. I've had at LEAST 100 that bothered to email me thanking my for turning them on to this. I installed mine about 3 years ago - and it's been absolutely flawless - including the alarm. I also installed it on my W202, and again, it's worked flawlessly - although the installation is a little different. I've had probably 10 or 15 folks with W126s that have done the install - and no, I have NO idea how to do this one.

Acky claims,

Not quite. Keep in mind that you MUST use relays (if your keyless entry brain doesn't have integrated relays) so that the (un)lock signal switches polarity upon lock/unlock. This way, the keyless entry will work with the factory alarm flawlessly.

Problem solved
 

Thanks for the replies. My post was asking for help with the problem of the OEM alarm not working with the remote. I also sent several private messages to people who might have the answer, without success.

Thanks anyway turbo300d but the remote worked fine from the start; yes it would not have worked without the two relays that was not the problem.

Bstreep, I'm sure it worked out for many installs. If my wife used only the remote and not the key though, we may not have known that the problem existed.

My Problem solved post was intended to advise others to test to make sure that the alarm is properly integrated with the remote. It was NOT intended to criticize your install info.
As far as the many who thanked you, I too thank you for your effort.

Thanks again,
Acky

Speedy & Acky,

You are absolutely right - it will NOT work correctly without relays. My instructions REQUIRE the use of a DSLV from Crutchfield (for the W124), and a different one for the W202s - which are a pair of pre-wired relays. Greatly simplifies the install for about $20, and provides those necessary relays :) .

Use of relays not the issue
 

Relays were never an issue, (I used two relays with the control unit).

If you read the first post in this thread, You'll see the remote worked fine, the problem was that the remote did not arm/disarm the OEM alarm - that's it.

I contacted the guy who posted the original instructions by private email while trying to sort this out, as well as to get info on wiring the close all windows/sunroof feature that works by holding the key in the lock position to close any open windows, unfortunately that was unsuccessful.

My final point is this, anyone who installs or has a shop install, a remote entry unit must make sure that it is wired so that the alarm is activated by BOTH the key AND/OR the remote. It is not enough just to have the remote lock and unlock the doors. If the system is not correctly tested and corrected if need be, you will have problems sooner or later.

That’s it. This issue is closed... unless someone is familiar with the convenience unit wiring circuit well enough to explain which wire to tap into in order to connect ground to the convenience circuit and mimic the key being held in the close position in order to close all windows by remote control.

Thank you,

Acky

Acky,

No hard feelings at all! :) I should also point out, that as these cars age, the outdated (IMO) Becker alarms start to act up. I have a buddy (without keyless entry) who's alarm would randomly go off while the car was RUNNING! The only way we could get the silly thing to turn off was to unplug the control unit in the passenger's footwell.

Regarding the convenience module, it's probably just a long pulse signal that goes to the unit. I believe that the key must be held in position for a few seconds? You might try configuring two relays to do momentary to constant output. Your alarm unit probably has an accessory wire that delivers a (-) pulse when the respective button on the remote is hit. This negative pulse will run through a relay and resistor and after running through another relay which is fed with 12V+, the pulse becomes a 12V+ output. However, it will *continue* to output 12V+ until you remove 12V+ or ground. You'll have to see what can do that, when the windows reach the fully closed/open position.

RKE on 124
 

When I installed a RKE about 7 years ago on my 87 300TDT I used DPDT relays, so the lock and unlock signals also drove the arm/disarm function.
Both locks and alarm work just fine.

Doug Quance

hey i have a 1992 mercedes 300E and i'm trying to install an aftermarket alarm. and i am so confused its not even funny. i know that there is a green and a blue wire hooked up to the vacuum pump which control lock and unlock but i don't understand what all i need to wire up to the blue and green wire. any help would be appreciated i've been looking all over for info on this and its just not out there.

Have you gone here:

http://www.peachparts.com/shopforum/showthread.php?t=11777&highlight=keyless+%24100