I finally had to join this forum as I’ve hit a dead end in my troubleshooting. I have a 2000 s500. My girlfriend parked it one night and it wouldn’t start in the morning. As it sat at the time, I could insert key, all dash lights would come on, all normal noises, steering wheel would drop into position, etc. I could move the key to position 2, radio would come on, everything normal, position 3 absolutely nothing…crickets. So I hook my battery up to my charger and it says battery is faulty. Battery was 6 months old, AGM, big (the correct one), but apparently dead. I turned it in under warranty and got a new one. Hooked it up, same problem. My gear selector shows up on the dash, no issues shifting it through the gears, so I go up and pull the starter relay. I turn the key to position 2 insert a wire and jumper 30-87 on the relay. All sounds from the car (enefgized
intake noise, etc) instantly stops. Lights go out, (and nothing from the starter), I knew I f*#ked up. I pulled up the carpet on the passenger side and I had blown a prefuse. I had an extra hole in the prefuse box, which I assume would be used up by a different model Benz, so I pulled the wire and stuck it in the other hole. I had power again. Still in the same boat w/ the starting though. Since jumping the relay didn’t work I figured I had a stuck or shorted starter, so I went ahead and replaced it. When I went to start it, same issue. So I figured maybe the battery had run down being parked out there for a few weeks. I hooked up the battery to the charger and it said faulty battery again. I took that one back. They gave me trouble about returning it and said they wanted to charge it over night. Next day I came in and it still tested bad 8v if I remember correctly. The guy working this day grabbed me a new one and said he wasn’t supposed to but he checked the brand new one off the shelf and it was also bad. 3 batteries later they found a good one and I was on my way. Hooked it up and nothing. I went and jumped the starter relay again and could get the starter to turn over but not start. I decided to order a new prefuse and install it in case my rerouting job was somehow to blame for my issues. I installed that, topped off the battery 12.7v, 100%charge, hooked the battery back up. Turned the key and it cranked for maybe 3 seconds but didn’t start. I tried a second time and nothing, no sound what so ever. I tried 8 or 9 more times and got like a 1 tooth movement on the starter once, the rest was all just nothing at all. I unhook the negative from the battery, hook it back up and it cranks for 3 seconds, then becomes inoperable again. I can repeat this over and over. It will crank once after it’s reset, but then seems like it’s getting a signal to not allow a starting sequence. I can put the key into the 2nd position and jump the relay and get it running with starting fluid but it doesn’t take over on it’s own. All fuses checked…what am I missing? It gets the handshake from the key, brake switch must work as I can move it through gears and get it to turn over at least once when battery is first hooked up. Hear selector also obviously works. After it stops cranking I can hear something activating from behind me, I assume the fuel pump, like 2 second bursts, maybe 4 or 5 times, then again my trunk is open, could be an antenna, not sure but something to note (this car has so many things actuating in start up, it’s like a space shuttle). I’m out of ideas. Help. Oh and the dealership is 4 hours away, and I prob know more than most of them, and don’t want to pay for them to poke around at this hourly.

 

OH! What Joys these MB's can be when 'virgin events' take place. Unfortunately, diagnosing the problem can seem impossible. So many 'systems' must connect to and coordinate with each other that. the daisy chain' of 'permissions' and activations can be onerous. For example, a single failure of one of the three (four?) independent 'anti-theft' micro-switches in the front passenger door handle can 'kill' the primary 'ok to crank/start' system. You will have to perform (get performed) a GOOD "STAR "analysis to sort this problem out and repair it. No other way.
Perhaps "BenzNinga" can help you out.

I once had an '82' Lincoln Town Car that would every 3rd Blue Moon would run the battery down over-nite. Many attempts by Dealer to duplicate and fix. While one day checking something else, touched electric choke---it was HOT--should have been dead--- WTF, over. Turned out to be one segment of the alternator rotor was shorted to ground and allowing the choke heater to back feed to the ground when the alternator would stop on the particular segment.

The same vehicle had an ECU that would 'freeze up' some rare times and shut off the fuel pump on start-up---a 'no start' condition. Numerous Dealer tows and parts replacements to no avail. Problem persisted for years. One day when down in Caracas, Venezuela while retrieving my local car from parking at the Theater, helped another man trying to start his Lincoln---with same problem--- no fuel on crank. When I diagnosed the no-fuel condition, he immediately connected the battery backward for a second. The car then started immediately. He related the ECU programing defect was well known there!!!!

 

"...with same problem--- no fuel on crank. When I diagnosed the no-fuel condition, he immediately connected the battery backward for a second. The car then started immediately. He related the ECU programing defect was well known there!!!!"

I have seen that "fix" work several times - but what was happening was that the momentary polarity reversal was kicking the stuck fuel pump backwards, allowing it to operate normally when proper polarity was established. I would never, ever do a polarity reversal on a modern vehicle with dozens of computerized control modules and computers!!

 

My guess is the entire prefuse distribution block is gone bad. Under the front passenger floorboard . get one from a junkyard.

Note there is a second pre-fuse back in the trunk by the battery I would get both of them and swap both of them out.

Charge the battery make sure it’s fully charged. Then try starting the car. If that doesn’t work you’re gonna need the four antitheft parts which consist of key ECU, EIS, and shifter, all taken from the same donor car as they are coded to work together.

 

I know there was a lot of info in my post, but I replaced the prefuse with a brand new unit from mb. The battery is topped off every time I attempt a start. I actually remove it too it off, hook it up and crank. And the eis (I believe) is working correctly. Errors with that would be me not being able to turn my key, shift through my gears, a failure of the gear assignment showing on the dash, and it wouldn’t allow me to crank the car over. Same w the brake switch. I’m able to move my car through gears, and turn it over once (and only once) when I install the battery. It seems like it senses a no start condition and then blocks the signal to start after that. I just don’t know what piece communicates this information. If my reasoning doesn’t seem sound or I’ve missed something let me know. I don’t know there to be an actual immobilizer on the car. If I pull the battery and reinstall it, it turns over once (but doesn’t start) so it really seems that whatever is stopping it can be momentarily reset by power cycling it. I think that’s the key to the puzzle. I pulled the fuses for the alarm system years ago due to a separate issue, so I know it’s not something there, as I’ve drove it for years without them being activated. And they are just alarms as best I can tell. Is there an immobilizer in this car? Maybe a reset button like some cars have after a crash that shuts the fuel pump off (don’t think that’s the problem, but some unit like that would warrant my attention). Thanks again.

 

I’ve scanned the car, can’t get somewhere w star as the nearsest dealership is 200 miles away and the car don’t start😒.
after rechecking every fuse, pulling my rear carpet (there was water back there must have come in the front and ran down the plastic channel the wiring runs in, dried it up, removed my rear Sam checked for corrosion, replaced my starter relay and the one next to it (motronic I believe), pulled both my sams out of the front and checked for corrosion cleaned and reassembled, again the starter is new, the battery is new, the large prefuses under the carpet are new… my scan came up good for eis, shifter and trans good, all other systems good (just so no one throws a “check your fuses under the carpet”,

my error is “start enable of DAS not sent”…
now from all the reading I’ve done there is no disabler on these cars just a series of “handshakes” of hash keys between the ecm, the shifter, and the ignition. I tried undoing the battery and holding the positive and negative cables together to try to discharge the capacitors (works on some cars). Hooked it back up and the car turned over for about 2 seconds and then back to doing nothing.

I checked the ECU codes for drive authorization and it says
“engine control module identified - yes”
”engine control module interlocked - yes”
“DAS and engine control compatible - no”

so my ignition recognizes my key, keeps continuous power to it, I am able to turn the key in all positions, my dash works, my accessories work, radio, steering wheel, all my gears show up on the dash, I can shift through gears freely, and on occasion (when I unhook my battery) I can get it to turn over a few teeth on the starter (only the first time). What isn’t communicating? It ran great for years, all I did was have a battery die. When I replaced it I had this happen.

I would get the ignition cloned to my car but the key obviously works, the scan tool says the ecm is good, it all worked before?

my spare key is the only key that opens my trunk, so it’s possible that these units have already been replaced, but they would have to have been replaced as a set. Is it possible that only part of the system (the ignition and other key) was replaced and cloned to the ecm? When they clone do they clone to the VIN number? If I get my ignition cloned to my VIN is it possible that my ecm won’t match my VIN? How do I check which if any of these parts are original if they don’t have VINs on them?

also is anyone seeing something I’m not? Thank you if you read this whole thing.

 

I don't know if you figured it out . But there is a hidden fuse box underneath the passenger side carpet. Check it to make sure the nothing is loose. I had a similar problem with my cl600 and that's what it was.

 

Yo mr. E30life, we mercedes owners like to use formatting on our paragraphs, because we usually communicate with words.

 

yes go to your local locksmith with both ignition new and old they can clone the old to the new on bench , secondly I just had a sale problem no key new eis new front Sam new battery new start new alternator still no crank no start I only get a crank if I reset the car by letting the terminals touch then reconnecting battery … there’s so many electrical components in this car it’s hard to pin point the exact problem I’ve had my car at 4 different shops 2 different locksmith/technician it’s getting over whelming I’m narrowing down to either trading it in or sale it

 

I realize this is really old, but did you ever resolve this?

 

Same thing is happening to me, i guess i'll try to replace my pump fuel and motronic relays and hope that the problem will get fixed hopefully, my engine basically cranks but won't start at all, i even bought a whole new battery and eventually installed it thinking that it was a battery problem

 

an engine that cranks, but will not start is either a fuel pump, fuel pump, relay, or most likely a crank position sensor