This is a copy of a post I made to a topic inquiring about a remote start in a W140:
I'll highlight in bold parts that you should pay special attention to with your 400E
I used to own a shop that specialized in auto electronics. Ultra high-end audio systems (did a couple systems with price tags well over $100K, lots $30-50K.) We also did lots of remote car starters, as I live in frigid Canada.
We were the only shop in the city recommended by BMW and Mercedes dealers.
We did lots of W140 pre-switchblade/pre-SmartKey cars. Easy (relative to some other Mercedes) system IF you know what you're doing. DON'T go to somewhere that has no Mercedes experience. Mercedes interior panels work differently than regular cars. These cars have many quirks that can trip up a regular electronics installer. I repeat: IF THEY DON'T HAVE MERCEDES EXPERIENCE RUN AWAY. They could do real damage to your car. Know how much an instrument cluster costs?
Ask if they use SRS and ECM safe testing/installing equipment. A circuit tester uses voltage to test the wire. Even a tiny voltage like the one given out by a tester will INFLATE AN AIRBAG. Or wreck your ASR/ETS/ESP computer. Special (read: expensive) testing equipment is needed to work on MB cars. We used a small ECM/SRS safe test light for tight spaces. Snap-On's best price: $600. For one small light, with no other stuff. Ouch.
(as an aside, pulling the fuse for your SRS may not disable it as the voltage required to fire it is so low, a static charge in the unit or on the line will be enough if the sensor indicates a condition to fire)
Ask them if they know where the tach pick up is for your car. You don't want them poking a tester into ignition system components. They need to know where it is, right off.
Ask them if they know how to by-pass the factory anti-theft system. You don't want them poking wires trying to figure it out.
Ask them what types of joints they use. Anything other than soldered for EVERY wire, run away. Ask for references from MB owners. We gladly gave that out.
1. The SmartKey cars CANNOT be equipped with a remote car starter. Mercedes will NOT release the encription codes for the anti-theft key. The double system of RF and IR, both using rolling code algorithmic encription systems is impossible to get around. We took a C43 completely apart, and couldn't solve it.
2. The Mercedes switchblade key can be broken, but the AAM computer will figure out that an unauthorized key is being used, and TOTALLY disable the car. It only takes a few remote starts, and your car is DEAD. Then, ouch, the system erases all the keys and you end up $$ light at the dealer. And you don't want to know what a new AAM computer and key set costs. The GDP of some nations.
3. You may no longer be welcome at some MB dealers. Some will NOT work on an automobile equipped with a remote start unit. Mercedes' factory believes them to be inherently unsafe. "The car should not be running unattended."
4. This will not be cheap, and if the price quoted to you seems "great", there is a reason. We NEVER did ANY Mercedes system for less than $1500. Quality takes time. Lots of it. Some MB owners were disappointed at the cost (we did Neons for $169 installed), but when they learned why, they understood. Also, the Neon didn't get top-line electronics.
5. Find about safety systems. We NEVER let a car out of the door without a sophisticated hood pin (series of electromagnets) system that detected when the hood was open and disabled the starter. That way you couldn't accidentally start the car with the hood up. If they show a puny spring operated pin, then you're in the wrong shop. If the car was put into gear, the engine would die. If the brake pedal was touched, the car would die. If the rpm broke a certain threshold, the car would die. The remote start system has to be tied into all those systems to ensure safe operation. If the shop says it's not required, RUN AWAY. Tying into all that electronic stuff takes time and expertise.
We did a 1993 S600 car. Top-line system, superb installation. By-pass factory security, added keyless entry. Price: $3500. 1/2 mile range with page-back to confirm start. Lock/Unlock status through page-back. Took a week to carefully dismantle the dash, install the unit, and reinstall interior bits. I'm sure we barely broke even after paying the labour charges.
BTW, the Mercedes SmartKey is the cat's ass of anti-theft systems. Nothing better sold today. Unbreakable even by techs with killer equipment.
We took a 2000 323i apart and broke the BMW radio-key system. 2nd toughest.
We broke all the Japanese systems quickly. Lexus almost on par with BMW, miles behind Mercedes
GM/Chryco/Ford's took about 15 minutes. Simple systems, easy to crack. Keep only joy-riders from taking your car.
Easiest car to steal? GM. and Dodge Neon. Gone in 60 seconds? What took you SO LONG!!!?
Anyway, be VERY careful when looking into having a remote starter installed on your Mercedes. It's NOT an easy thing to install (despite the claims of some systems sold over-the-counter touting DIY install) and takes a huge amount of knowledge, equipment,and time.
1998 C230 "Black Betty"