I installed my Renntech electronic lowering module yesterday and thought I would share the procedure with the Board. About a third of the way into it, I was thinking WTF am I doing, but by then I was too far committed so I plowed ahead. You can't imagine the relief I felt when I determined everything was installed perfectly and working correctly on the very first attempt. A special thanks to psk145 who quickly responded to my PM asking about the messed up installation instructions (more about that later).

I purchased my version 2 ELM kit a month or so ago and then last week, decided to once again fulfill my late father's prophecy for me of "a fool and his money soon part" by purchasing the new Renntech remote control unit directly from Renntech. Turns out though, I ended up thinking the remote was worth every penny I paid for it. Plus, the cost of the remote was easy to rationalize when I amortized it over my expected ownership period of my car. After all, what's better that you're going to replace a W211 E55 with? Very little indeed and now I get to diddle with the car's height settings via the remote whenever I want to with complete ease. Any, Renntech was very professional and I received the remote very quickly after placing my order.

The ELM kit looks like this:



Included in the kit are the module, the wiring harness, the 8 pin connector, and a few other miscellaneous pieces, along with the installation instructions.

The key to doing the install is the 8 pin connector, pictured here:



The majority of the install is moving wires from the factory wiring harness to the airmatic control unit to this 8 pin connector, and then inserting wires from the ELM harness into the corresponding pin holes in the factory harness.

Before beginning, it's best to have the necessary tools on hand:



You will need a 10mm socket (battery disconnect and unfastening the control unit mounting plate), a Philips screwdriver (opening the module), a small flat blade screwdriver (to assist with removing the factory harness endcaps), a Hazet 4673-1 (pin removal), a magnifying glass (to help see the tiny pin numbers molded into the factory harness connectors), a pair of pliers (to close the crimp on connectors), a small pair of wire snips (to snip the small cable ties holding the factory harness to the pin sockets, a multimeter (for performing continuity checks), and a couple of small cable ties (to re-secure the factory harness to the connectors. I also highly recommend printing out the wiring schematic that Renntech provides at their website since the schematic provides the color code of each wire you will be working with. Finally, it's wise to confirm whether your E55 is equipped with either four-wire airmatic sensors (most common) or three-wire airmatic sensors. I confirmed mine has four wire sensors by visually inspecting the sensor at the front left wheel. The wiring procedure will vary depending on which sensor your car has. Finally, note that the W211 has only three actual sensors mounted - one at each front wheel, and one serving the rear end of the car.

With the instructions, schematic, ELM kit and tools on hand, it's time to begin the install. First step is to disconnect the car's battery in the trunk:



Simply use the 10mm socket to disconnect the ground cable from the battery.

The next step is to access the airmatic control unit. To do this, remove the passenger side floormat, if your car has one. Then fold the carpet towards the passenger seat, explosing a large insulating piece of molded foam. Remove the foam panel by sliding upwards out of its mounting slots. Once removed, you will then see the backside of the airmatic control unit mounting plate:



The mounting plate is secured by three plastic 10mm nuts, one at the top, and two at the base. The one towards the outside of the car is somewhat concealed, but it's there. Just feel for it with your fingers, and then use the 10mm socket to remove the nut. Once the nuts are removed, lift the plate up and back towards the seat:



The airmatic control unit is on the right. In the next picture, I have removed the factory wire harness connectors from the control unit:



The connectors are removed by sliding the release on the connector towards the seat for the connector closest to the seat, and towards the firewall for the connector closest to the firewall. At this point, you can snip the cable tie on each connector on the harness in order to release the wire bundle from the connectors. In addition, you will want to peel back some of the friction tape used to bundle the wires in order to give yourself more wire to work with in swapping the wires around.

In order to actually remove the wires from the harness, you must first diassemble the connectors by removing the endcap on each connector. I used the small flat blade screwdriver to gently pry the endcaps off. With the endcaps removed, you can slide the wire mounting connector out of the harness. Here's a photo of the harness connector with the endcap removed and the wire mounting connector partially slid out of the harness connector:



Once the endcaps are removed and the wire connectors have been slid out of the connectors, you are then ready to begin carefully swapping the wires around. I can't emphasize enough having the wiring schematic available so that you can always confirm the wire you are removing from the factory harness by its color coding. Although not necessary, I used the Hazet tool to depress the pin tabs to free the wire pins from the connector. The Renntech instructions are very clear about which pin numbers must be moved. Here's a shot taken after the factory wiring connector lost its virginity by giving up its first wire and having it reinserted it into the 8 pin connector mentioned above:



The final two steps are where I had a brief moment of distress because the included instructions are inaccurate. Instead of having the battery positive and ground connections removed from the harness as shown in the instructions, my kit instead included crimp on connectors that the ELM harness plug into. No big deal, but a little spooky when you're about 90% done and all of a sudden the supplied instructions are worthless. It was pretty obvious how the power was supposed to hook up, though, and I finished the connections. Here's a shot of everything rewired to the ELM:



Once everything was wired up, you simply follow the remaining install instructions - set the ELM at position 1, the wheel adjustments at position 3, and then hook up the remote control unit by simply plugging the ELM harness into the remote unit. Then you reconnect the car's battery (and hold your breath hoping for no sparks or puffs of smoke).

The ELM harness has a nice long cable for the remote, meaning you can locate the remote just about anywhere you'd like to. You can turn the module on and off with the remote and make all adjustments through it as well. If the remote is installed, it overrides the switch settings on the module. In other words, whatever position settings you have the knobs set on the module are overridden by the remote, which fully controls the module.

Here's a shot of the main menu of the remote:



There are additional options on the main menu if you scroll further down.

Here's another shot of the remote:



Through the remote, you tell the ELM that it's hooked up to a Mercedes, and then set it as an E class. The module then pauses momentarily as it sets itself to specifcally control a W211. Individual height adjustments are possible in .2" increments:



With one of the screens, you can display the settings of all sensors:



This following picture shows a much lower setting for the car:



Here's the information screen on the remote. Not much use to an end user, but if you have problems, lets Renntech know the hardware and software versions of your ELM module.



Finally, here are a couple of shots of my car with a drop:





Once I confirmed all was functioning flawlessly, I replaced the cover on the ELM, and reinstalled the airmatic mounting plate up against the firewall. Once everything was buttoned back up, the last step is to reinitialize the windows and sliding sunroof (reset necessary due to battery disconnection).

I am very pleased with the Renntech ELM and especially like the easy functionality of remote control unit. Although not shown above, the ELM can also be set to automatically reset the factory ride height once the vehicle attains the specified value (that you set via the remote). Not having to open and reopen the module to make adjustments, or to have to extend the control knobs more than justifies the added expense of the remote. It's a super slick controller for the module and is very intuitive and convenient to use.

The install was a fun challenge, and doing it myself helped me really better understand how the system is designed to work. I know I am late to the game in doing a lowering module, but I give the Version 2 Renntech ELM, with remote a two thumbs up as an excellent upgrade for the E55.

 

Wow that remote is awesome. You can adjust on the fly?

 

nice write up, thank you.

 

great write up. I like that remote but can't see myself spending $600 for it. I hope the price comes down. Any pics of your car?

 

Very nice write up!!

 

nice write up. Glad everything worked out. The remote is awesome looking.

 

Nice write up. I also got a little stumped on the ground and power. I figured it was the crimp and was relieved that the thing actually worked when I turned it on... How much was the remote? I have version 2 and have contemplated the remote, but I rarely change my settings so I can't really justify the cost. Did you run the remote to under your cup holder?

 

Wow, thanks for that. You are a much better man than I am. Here are my DIY directions:

1. Hire someone else

 

Thanks for the great write up! Looks like you put significant effort into documenting the process for everyone else.

 

Trust me, that's about where I was when I wrote this above:

Anyway, when I decided to do it myself, I was thinking how hard could it be to swap eight wires around? After I spent about 15 minutes just on contemplating how to disassemble the factory harness connector without breaking it so I could actually swap a wire, I was definitely beginning to think it could be hard, really hard to swap eight wires around.

 

Great write-up. I am sure it will be helpful to many.

 

Great write up. If you don't mind me asking how much did you pay just for the module? Thanks again in advance send me a PM if you wish.

 

Great Job! Bound to be a stickie!

Thank you for taking the time to make a fine contribution here at MBW W211 AMG board.

 

very good write up thank you

 

where can i buy the Renntech ELM or any ELM for that matter?

 

+1. I wish I can do it myself.

Nice write up S.

 

Seriously, awesome writeup! I'm pulling back the carpet as we speak.

Here is instructions I was directed to on the Renntech website that DIDN'T come with my unit (v2 purchased days ago).

Very Good Addition Documentation
http://www.renntechmercedes.com/support_files/mb_lm.pdf

 

So let me get this straight? You could do adjustments to your suspension settings on the fly? That is awesome!

 

With the remote, yes.

 

remote looks like mp3 player...

 

So lowering your car is done by a module now and can be done on the fly!?!? No springs/shock replacement? Sorry, I'm new. I currently have a S4 with coilovers that I have to manually adjust if I want to change height.

 

coilovers vs. Airmatic suspension, thats the difference

 

A quick tip/pointer for people w/ "visit workshop" message after the installation:

I have an 05 E55 w/ 3 wire airmatic system. I followed the Renntech instruction and I got a "visit workshop" message along w/ my car not being able to be lowered at all. It was stuck at normal position.

After a quick research, I re-installed using the instruction for the 4 wire airmatic system. Problem solved. ELM works flawlessly.

 

I got the renntech elm v3 (James ACG) put in (usb port for changing the settings w/laptop). I notice that when i'm at a stop light, the elm lowers the car each time when its stopped...is this the case with others that have the renntech elm?

I wonder what the setting is when its moving? is it what i put into the module (2.05f and 1.95 r)..sort of confusing to be cause it lowers more when at a dead stop....

 

Renntech V3 elm and same issues with lowering at a stop and raising as soon as the car goes. literally tucking tire f and r, then 1 finger gap when it moves. waiting to hear from James @ acg to see what the verdict is. I'd actually prefer it to stay one height unless I change it