Aftermarket keyless entry - PeachParts Mercedes-Benz Forum

john420 · #1 04-02-2003, 10:26 PM

Just wondering if anyone had experience with remote keyless entry systems working on the "central locking system". I don't even know if it's possible, but they are a real convenience once you get used to them, plus I can't stand having to lock the doors with the key every time.

Blu 420Sel · #2 04-02-2003, 11:27 PM

Here you go:

EASY to install keyless entry in W124/W126

#3 04-03-2003, 07:12 AM

I cringe when I see the kids in these aftermarket shops cutting into a wiring harness. I would NOT add any aftermarket electronics without fabricating a wiring harness that would plug into existing connectors. I WOULD NOT cut or allow anyone else to cut a single wire anywhere on a factory wiring harness.

What is the problem with using the key? It cant' take more than 3 seconds to lock the door and drop the key in your pocket.

I have seen a number of cars over the years really butchered with aftermarket electronics installations. I even saw a car burn once that turned out to be directly related to electrical installation incompetency.

Good luck with whatever you decide to do,

Blu 420Sel · #4 04-03-2003, 08:10 AM

I know what you mean Larry, there are a few good shops out there but there are a lot more worse ones. I wouldn't think about doing it unless I was going to do it myself.

Plus the fob is just one more thing to clutter up my pocket...

jsmith · #5 04-03-2003, 09:03 AM

The keyless entry portion of it is fairly straightforward but the knowledge is obscure. MB hookups are unique and require specific relay connections that are very different from other applications. That is why it is essential that the installer has experience specific to MB's. The other part of the equation has to do with additional features such as flashing light / horn confirmation. If the installer is knowledgeable about MB's then that shouldn't be a problem. I won't even go near a remote start although I've heard it's doable.

Cheers

Blu 420Sel · #6 04-03-2003, 09:10 AM

John,

Spend a little time on the car audio forum. Scott has the kind of experience Jsmith is talking about and I'm sure he could field all of these questions pretty easily. Let us know if you try it.

Good luck!

sbourg · #7 04-03-2003, 11:10 AM

Just installed an alarm/keyless entry on our 190E 2.3 that had no factory alarm. It was a lot more work and frustration than I expected to encounter, but the plus side is I know more about the car now. The unit is a Commando 520-S ($49), which includes two three-button remotes, parking light relay, starter disable relay, shock sensor, and all the little bits and pieces. The keyless entry part requires 2 additional Bosch-type relays, and you will need lots of extra wire, connectors, heat-shrink, solder,... for the whole job.

If you were just installing a keyless entry, it can be done under the rear seat next to the pump, with a minimum of additional wiring. The pump, by the way, is referred to as a 'vacuum' pump, but this is a confusing simplification. It sucks or pumps air, depending on the state of the trigger signal it receives, and this allows just one pneumatic line to each actuator to do the job. It also has a built-in pressure (or flow) switch that stops it when resistance increases. That is how the trigger can be just 12V or ground, without pulsing or timing. This simple pneumatic logic is also why all the locks must go together when they go - no 2-stage driver's door then the rest. Your keyless entry control must have a long pulse option - 2 seconds or longer.

One thing you will need to wire in is the parking light flasher - this car needs a pair of high-current diodes to flash both left and right together without disturbing the independent design. These wires should be available somewhere under the rear seat too, but in my case installing the diodes on the light switch inself was easier and less invasive. Constant 12V and ground are available along with the trigger lines right at the pump, and I believe a valid 'switched power' line as well, if needed.

If your car does not have the factory alarm harness and you are installing an alarm, it can be a job finding all the right triggers. If you have never dealt with car alarms before, it can also be confusing sorting out the functionality and termnology used.

For instance, I found there is no problem using pin switches as triggers if they hook to a lamp that uses a constant 12V as source - or no lamp at all. Trying to use the glove box switch as a trigger gave me fits, though. Testing with the lamp removed it functioned properly, but the system gave an error and disabled that zone when the lamp fixture was plugged in. That lamp only functions when the ignition is on - when off, the line is very noisy from something else connected to that circuit.

I had also modified the system - I fed a 'diode-or'd' line back from the alarm 'unlock' output to the dome light trigger input of the alarm. This would turn on the dome light when the 'unlock/disarm' button was pushed on the remote, but it also disabled the 'auto re-arm' feature, which relocks and rearms after 60 sec if no door is opened. Another relay and more digging for wires would be needed to do this properly, so for the time being I disconnected my modification.

Since there was no factory alarm, there was no line connected to the trunk lid switch and no switch or line for the hood. The former I added, and the latter now has a wire awaiting a switch.

Larry asked 'Why?' - and after all the effort of the installation, I was beginning to wonder myself. One big plus is what I perceive as the fragility of the MB key/lock design. The fewer uses, the better the condition of the locks and the keys, and the reduced likelyhood of expensive failure. A lot of my rationale was the combined alarm/keyless features, though, not as much an issue if you have factory alarm, or if a keyless unit could not be integrated with the existing alarm.

Another issue to consider is the trunk that does not lock on closing - but locks with the door locks. This is different from all the other cars we have owned, and the Honda we currently do, where the trunk is locked when closed. It is a habit to lock the door of the 190 when exiting, and both cars are functionally the same this way if you don't then need to access the trunk.

When commuting to work though, I do, and I just 'pop' the trunk before getting out of the Honda, and then lock the door. With the 190, I lock the door, curse when I get to the trunk and unlock it, grab my stuff and close the trunk ... and often forget to relock the trunk and thus the whole car. The keyless remote provides a unified procedure you execute as you walk away from the car, and gives both audible and visual indications the task is done. For me, anyway, that is what works.

Steve

95e320 · #8 04-03-2003, 11:25 AM

Very good post!

I am about to put in keyless/remote start on my 95e320. I don't see a huge problem as one can find all the information in the wiring diagrams that come with the MB CD.

Thanks for the tip about the diode. I was thinking of using relays for that...

Quote:

Originally posted by sbourg
Just installed an alarm/keyless entry on our 190E 2.3 that had no factory alarm. It was a lot more work and frustration than I expected to encounter, but the plus side is I know more about the car now. The unit is a Commando 520-S ($49), which includes two three-button remotes, parking light relay, starter disable relay, shock sensor, and all the little bits and pieces. The keyless entry part requires 2 additional Bosch-type relays, and you will need lots of extra wire, connectors, heat-shrink, solder,... for the whole job.

If you were just installing a keyless entry, it can be done under the rear seat next to the pump, with a minimum of additional wiring. The pump, by the way, is referred to as a 'vacuum' pump, but this is a confusing simplification. It sucks or pumps air, depending on the state of the trigger signal it receives, and this allows just one pneumatic line to each actuator to do the job. It also has a built-in pressure (or flow) switch that stops it when resistance increases. That is how the trigger can be just 12V or ground, without pulsing or timing. This simple pneumatic logic is also why all the locks must go together when they go - no 2-stage driver's door then the rest. Your keyless entry control must have a long pulse option - 2 seconds or longer.

One thing you will need to wire in is the parking light flasher - this car needs a pair of high-current diodes to flash both left and right together without disturbing the independent design. These wires should be available somewhere under the rear seat too, but in my case installing the diodes on the light switch inself was easier and less invasive. Constant 12V and ground are available along with the trigger lines right at the pump, and I believe a valid 'switched power' line as well, if needed.

If your car does not have the factory alarm harness and you are installing an alarm, it can be a job finding all the right triggers. If you have never dealt with car alarms before, it can also be confusing sorting out the functionality and termnology used.

For instance, I found there is no problem using pin switches as triggers if they hook to a lamp that uses a constant 12V as source - or no lamp at all. Trying to use the glove box switch as a trigger gave me fits, though. Testing with the lamp removed it functioned properly, but the system gave an error and disabled that zone when the lamp fixture was plugged in. That lamp only functions when the ignition is on - when off, the line is very noisy from something else connected to that circuit.

I had also modified the system - I fed a 'diode-or'd' line back from the alarm 'unlock' output to the dome light trigger input of the alarm. This would turn on the dome light when the 'unlock/disarm' button was pushed on the remote, but it also disabled the 'auto re-arm' feature, which relocks and rearms after 60 sec if no door is opened. Another relay and more digging for wires would be needed to do this properly, so for the time being I disconnected my modification.

Since there was no factory alarm, there was no line connected to the trunk lid switch and no switch or line for the hood. The former I added, and the latter now has a wire awaiting a switch.

Larry asked 'Why?' - and after all the effort of the installation, I was beginning to wonder myself. One big plus is what I perceive as the fragility of the MB key/lock design. The fewer uses, the better the condition of the locks and the keys, and the reduced likelyhood of expensive failure. A lot of my rationale was the combined alarm/keyless features, though, not as much an issue if you have factory alarm, or if a keyless unit could not be integrated with the existing alarm.

Another issue to consider is the trunk that does not lock on closing - but locks with the door locks. This is different from all the other cars we have owned, and the Honda we currently do, where the trunk is locked when closed. It is a habit to lock the door of the 190 when exiting, and both cars are functionally the same this way if you don't then need to access the trunk.

When commuting to work though, I do, and I just 'pop' the trunk before getting out of the Honda, and then lock the door. With the 190, I lock the door, curse when I get to the trunk and unlock it, grab my stuff and close the trunk ... and often forget to relock the trunk and thus the whole car. The keyless remote provides a unified procedure you execute as you walk away from the car, and gives both audible and visual indications the task is done. For me, anyway, that is what works.

Steve

jay3000 · #9 04-03-2003, 03:00 PM

It's a little pricey, but it might save some time, and frustration..

http://www.bergwerks.com/keyless.jsp

jsmith · #10 04-03-2003, 03:57 PM

hehe, someone took the DIY keyless entry threads on this site, packaged 2 $5 relays with the instructions and is selling it for $140!

jay3000 · #11 04-03-2003, 04:09 PM

Quote:

Originally posted by jsmith
hehe, someone took the DIY keyless entry threads on this site, packaged 2 $5 relays with the instructions and is selling it for $140!

I wish I could figure out how to gather enough info from this forum to feel comfortable enough that I had everything I needed..I found a wiring diagram in a link in this thread, but it doesn't really look like what I need...I've done two other keyless entrys, but I really don't know where to go with this system...

jsmith · #12 04-03-2003, 05:01 PM

ok here's my collection, the key is to understand how the relays have to be wired and how you splice into the harness (it's just one wire that drives the pump):

Relay Guide

Trunk method (this was the approach i took)

Mercedesshop guide

Simpler method than mercedesshop procedure

They are all hard to digest and you have to map out all the different pieces of information.

I would get the remote unit working before installing and make sure it supplies the +12v and ground as required before hooking anything up. I used a lantern battery for this purpose. Then I would get it working locking and unlocking the car and last I would hook up any light flashing / beep convenience features(don't have those links cuz i didn't do em).

jay3000 · #13 04-04-2003, 09:00 AM

I think I can take all of that info, and combine it into something I feel comfortable with..

Thanks for all of your help...

jsmith · #14 04-04-2003, 09:15 AM

jay3000,

this was an enjoyable undertaking for me. i had electronics shop in high school (loooong time ago) so i am dangerous with a soldering gun. i actually used a $29 jcwhitney keyless entry unit with built in dual relays. i figured out how the relays were wired, took them off, modified the PCB and put them back on. with that approach i didn't need additional external relays. i hooked up in the trunk following that second link. kept me engrossed for a couple of days! it's a great DIY project but i might upgrade the unit to one that as a chirp or beep confirmation at some point....

jay3000 · #15 04-04-2003, 09:47 AM

It will make my wife very happy... And that's always a good thing.