Positive Charge Door Lock? - PeachParts Mercedes-Benz Forum

pshibly · #1 06-03-2002, 04:57 PM

What do MB use? Positive or negative door locks? when buying my alarm they asked me if i had positive or negative door locks. heres the part name:
Door Lock Relay Module. For Vehicles with Positve Polarity Door Locks

should i have them ship this or do MB's use negative polarity Door locks? Or do they use neither. I have no clue!!

stevebfl · #2 06-03-2002, 06:03 PM

This has got to be a trick question. MB door locks are vac/pressure driven, but the door locks do drive the ATA switches (anti theft alarm) and these switches are grounding switches which means that one terminal pulled to ground arms it and another pulled to ground disarms it.

engatwork · #3 06-03-2002, 06:06 PM

LOL

pshibly · #4 06-03-2002, 07:45 PM

ok. so i wouldnt need to positive module converter? i called them up and they said my car has a positive charged door lock. but then again, theyre probably saying that so i would have to buy it. i know ours run on vacuums but what the heck is this thing? check out the commando 2-way pager alarm. it comes as an option for your car if it needs it.

pshibly · #5 06-04-2002, 03:29 PM

ok. i found information on our vaccuum door locks. i realizes it changes polarity in order to lock/unlock door. here what i found:

Found mostly on Mercedes Benz vehicles, the movement of the door lock actuators is controlled by a central vacuum pump. The switch changes polarity on a single wire that may rest at power or ground depending on the state of the door locks. You can duplicate this with at least a 2 second pulse. If the alarm or keyless entry you are installing does not have a 2 second or longer duration option for the door lock outputs, do not use this diagram (it will not work unless you incorporate a timer into this circuit).

blackmercedes · #6 06-04-2002, 07:31 PM

On MB's you can, as you've found out, tie into the electrical portion of the vacuum operated system, triggering the system using relays.

The other method is to use an actuator in the door to operate the pin up and down, replicating the operation of turning the key.

On later cars with a dash mounted switch, it's simple to tie into that switch.

If your installing shop is unfamiliar with how MB door locks work, then run away. Working on German cars takes a certain expertise. Your door panel is an expensive piece of interior body-work, not some el-cheapo Chry-co part.

And don't go probing wires under the dash without knowing where your SRS wiring lies.

pshibly · #7 06-04-2002, 08:18 PM

can you post some pointers to installing an alarm. mines got keyless entry, door sensors, shock sensors, remote start, and all the goodies. im hoping to learn from this, plus i dont wanna pay a good deal of money to have it done. thanks.

pshibly · #8 06-05-2002, 01:12 AM

bump.

blackmercedes · #9 06-05-2002, 09:24 AM

Unless you're pretty familiar with auto wiring, have someone install it for you.

Tie the door sensors into your dome light circuit. For your starter-kill, throw away any relay that came with the alarm unless it's a Bosch. Use ONLY a true Bosch relay for your starter kill. If you want to install a trunk-open sensor, run wires back to the truck light circuit.

You've got to bury the brain DEEP, so that a thief can't locate it easily. The best way is to remove the dash and mount it to the firewall, but that's probably a bit much for DIY. Take the glove box out, and bury up behind there.

Forget shock sensors. False alarm crazy device. If you do use it, mount it to the sterring column and test it by hitting the windscreen.

Don't use a NON-ECM SAFE test light in your car. Even older MB's have airbags and electronic modules on-board. And don't probe an SRS wire, no matter what kind of test light you use. The firing mechanism for the SRS uses extremely low voltage, and even a static charge can cause a bag to deploy.

Not to burst your bubble, but most driveway-install alarm systems slow even amateur thieves down for maybe a minute. If you don't incorporate the wiring into the factory looms, it's easy to find. That means your starter kill relay is vulnerable. Siren wires are found quickly, and the siren is almost a waste of time. Good security uses a pager and two transmitting antennae, or a phone system.

As to your remote start, I gave a primer on using a remote start in a Mercedes:

http://www.peachparts.com/shopforum/showthread.php?threadid=13404&highlight=remote+start

Good luck...

pshibly · #10 06-05-2002, 02:34 PM

wow. this stuff appears to be more complex than i thought. i figure if i can find a wiring diagram of my car, then it will be much more easier than testing all the wires to find the right one. ive stopped by a few alarm places in town, and they dont even work on crimestoppers because they tell me they dont have enough experience to put in such a complicated alarm. what kind of prices am i looking at to have someone install it for me?

blackmercedes · #11 06-05-2002, 05:35 PM

For any non factory anti-theft Mercedes without traction control, we would do a complex alarm and remote start with full features and top-line gear (good wiring, solder joints, brain buried DEEP, remote start with full safety, etc) for about 12-15 hours labour.

Final bill would be about $7-800 for labour. But, perfection costs money.

Anyone quoting you much less than $3-400 is going to do a hack job.

And don't forget that the wiring diagram doesn't show WHERE the wires are, just what they're connected to. Take LOTS of time to examine it and learn your way around.