How it started:
So I purchased a 2002 w220 S430, 170k miles runs drives, some interior tlc to be done, all rear electronics didnt work.
Since the first day I went to check the car, ignition switch had issues turning, but after 5 or 6 tries it turned and engine starts immediately.
Car ran great.
drove it home, checked rear sam module it was under water, before buying a new one, I opened it, cleaned it with electronic cleaner and a tooth brush, It looked perfect! heat gun dried it, cleaned connectors, installed it and everything works now!, had issues with rear tail and turn lights, rear shade blind, now I even get a rear brake pad wear message on dash.
Was super happy !! basically had to clean the car get 2 tires and done!

Going down hill:
This morning I went in the car to check if battery has drained (in case some module didn't sleep specifically testing the rear sam) and again had some issues turning the ignition key but after 5 or 6 tries it started, first try, warmed engine, tested everything all great! shut the car off went to work.

Since I purchased the car stereo didn't work, this afternoon, I checked stereo fuses and went to open the ignition switch to check radio, so here it goes, 5, 6 ,7 times and switch would not turn, could hear the small motor/lock mechanism trying to free the switch (like it did since I purchased it) and maybe at the 9th try, I could not hear the mechanism anymore, tried pulling the key and reinserting it several times but nothing, no sound, no message on dash nothing. I pressed the fob buttons to unlock/lock the doors (which were working perfectly fine) and now they dont work!!.

I dont know what happened, I have checked all fuses one by one, even the primary fuses under rear fender and under passengers seat.
Have checked electric diagrams, and cant find an specific fuse for EIS or alarm modules. THere is one for models 09/2002 and up (fuse 78) on the side of dashboard, but mine is an 05/2002 which doesn't have this fuse block.

I can see this problem is common, sorry for long question, but wanted to give some info on how things developed.
Again, I dont see any warning of wrong key or anything on dash. car battery is new has 13V and just replaced key fob battery with new ones, also tested that fob is sending unlock, lock signal with a scanner and its strong and steady.

Please please help

Thank you in advance for any help.

 

I'm not really knowledgeable on this problem, so won't be too much help, but I do have some comments.

The battery in the key fob has nothing at all to do with the problem that you are having., nor does the lock/unlock function.

The lock/unlock/starting functions are powered thru induction coils in the key fob, powered by the ignition module. The signals are sent thru induction.as well. Some signals are sent by the IR (Infrared) system in the key fob thru the window in the end of the key fob, and the window in the switch socket. Probably not the problem, but you might try cleaning both windows.

Hopefully, one of the experts will chime in with some better answers.

 

I haven’t read the thread in depth, my apologies but what immediately comes to mind is, do you have a spare key to try? I have heard of the keys not working sometimes and needing replacements

if you have a spare it will tell you whether the issue is with your key or the ignition

the ignition runs off of infrared, try cleaning the sensor on your key maybe

edit:read the full thread, yes you need to try a spare key. If you don’t have a spare key this is a good excuse to order a backup anyways. After twenty years I can imagine this key has probably gone through the washing machine more than once,

as far as dashboard fuse panels you are correct, our 2002 cars only have 3 main fuse panels. If you can’t find any fuse for ignition it is most likely an electronic fuse built into one of the sams

lastly, I’m not sure I’d recommend a heat gun for drying out electric parts? They can get fairly hot and you may have cooked a resistor/capacitor, or even loosened a solder joint with too much heat. I always use compressed air to dry out and dust off electronics

 

First, rice is the best way to dry out electronics, put the item in a plastic bag full of rice (fresh uncooked) and wait 24 hours. If the module was under "dirty" water that's another issue, you might need to get some electronics cleaner to dip or spray the module board with to clean off any contaminants, doesn't take much to mess up the electronics. And yes, unless you were super carful you could have cooked something on the board with the hair dryer.
As for the key not turning, there are a couple of things that will keep the key from turning, the car has to be in Park or Neutral, so maybe the shifter is out of alignment and the second is the brake switch must be depressed as in your foot on the brake. If the switch is out of alignment or defective, no start, Does the dash light up normally?

 

Sorry to not have updated this, I finally fixed this about 5 months ago, removed drivers side foot trim and lifted rug, found that the connector which carries 12V to the EIS was corroded, had to bypass it with a wire. (red wire) sorry no pics
Everything is good now? (after $290) for a key that I did not need.
Hope this helps somebody

 

Thank you for the update I'm going to check that cable tomorrow!

 

Hope it fixes your problem! Let us know!

 

I finally got my 2001 s600 amg fixed after countless mechanics telling me to junk it. It was my rear SAM unit and a loose wire on the trunk. It cost me $350 and a mechanic from Craigslist in Atlanta named Yergov from Russia repaired ithe rebuilt my SAM unit in the rear and replaced my passenger side unit because I had purchased a new one but never installed. Now I just need new ignition packs to pass emissions

 

you found a real mechanic who knows how to repair things , not just a “parts changer” which is what most mechanics are these days