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Help!! No-start issue!

2K views 23 replies 9 participants last post by  samosali 
#1 ·
Hi guys -- just got into my car, and it won't start.

I put the key into the ignition, turn it to first position, everything lights up the way its supposed to, I hear all the usual noises, radio comes on, then I turn the key and nothing. No crank, no movement, nothing. It's exactly what would happen if you tried to start the car with the security system engaged (it's not, I checked).

There's literally no mechanical movement whatsoever, but all the electrics stay on and behave normally, so I'm leaning towards it being something relatively superficial (maybe a fuse? maybe the security system isn't turning off even though it flashes green on the door handle?) Could it be the starter motor?

Any ideas for quick fixes I can try tonight? Otherwise I'm having it flatbedded to my mechanic in the morning.
 
#4 ·
Never heard of this problem being rooted in whatever K40 is. I've only ever heard this issue in relation to the ignition starter switch just being worn out. I'm starting to experience the same thing; turn the key to start, but I get nothing except lights. After the second time trying, it'll start and most days it's fine.

And I can't find a K40 in STAR Finder either.
 
#14 ·
Everything I've Read Points To...

The 3 things I recall reading about in such situations:
Neutral Safety Switch
Ignition switch
Voltage Regulator

These items were NOT specific to the W140, but my info is combined with the W124 also.

sbaert, jayare, floobydust, Merc-S600 and others are excellent sources about such conditions. Googling the forum box is always recommended. There are HOURS of info about this topic. :read:

The questions I would ask you:
Age of the battery.
Age of the voltage regulator.
Mileage of the vehicle.
Have you checked for bad grounds at major connections? Removed and inspected fuses?
How about the fabled Crankshaft Positioning Sensor/cable?
Previous symptoms indicating ANY electrical issues.
Do you feel any wiring getting HOT after you try starting the engine?
Have you tried getting someone to turn the ignition while you listen for clicks etc. under the hood?

Any unusual driving conditions such as driving thru high water, rain, mud/dust, extreme cold/heat, pot hole hits, long drives, many short drives where you turned the engine on/off many times in short succession, any sticking in the ignition switch, dead spots in the switch, key jamming, tranny shifting issues, recent maintenance, lights dimming, radio kicking in and out, CEL or other dash lights blinking or intermittent...? :confused:

My 1st choice/guess would be the Neutral Safety Switch.
It's gonna be something simple. This kind of problem drives me bat sh*t crazy. :banghead:
 
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#15 · (Edited)
i am almost sure that his car does not have voltage regulator as such. it is actually a part of ground module in the computer box under the hood.

this is important: if your plastic bushings (two of them) on the lever between gear shift and transmission are worn or missing then neutral safety switch cannot operate like it should. you can check it in one minute once you are under the car. the bushings are visible. namely the switch is controlled by same lever as transmission is. In addition, this switch which is mounted on the transmission body can be adjusted (its position).
 
#16 ·
Bridge the Starter Motor connectors with a screw driver , maybe the brushes are stuck .
If you never done this ,this is how it's done , :Ignition on ,screw driver transverse across the starter terminals, sparks will fly but harmless , if the engine starts ,its time to change the starter motor if not ,check Relays as mentioned.
Check link I added then , Relay F K38/3 in picture on the last orange chart .:thumbsup:

http://www.benzworld.org/forums/w140-s-class/2730153-fuse-box-relays-explained.html
 
#17 ·
Just called the flatbed, so off it goes to the mechanic.

I agree that it's probably going to be something simple. My battery was replaced about two years ago, no idea on the voltage regulator though. Just turned 140,000 miles. But I doubt it's the battery because it's literally not even trying to crank. There's no clicking noises under the hood or anything else either. Just turn the key and nothing, but everything else works fine. Even the A/C comes on. Don't know about the crankshaft sensor either, but that never gave me any trouble in the past. I've literally never had any electrical issues, no dimming, nothing like that. No unusual driving conditions either; just normal standard use of the car. To be honest, I haven't really been driving it as much as I usually do over the last few months.

Only recent mechanical issues include a fuel pressure regulator replaced last week and a bad PSE pump that I haven't gotten around to replacing yet. The car runs like a top though; never had any serious mechanical problems, never had a transmission issue, key always functioned fine as well.

As for dash lights, recently the SRS light has been staying on for a few minutes longer than it should, but it does go off. Was going to have the code checked anyway to see what's up. Could that be related?

We'll see what the mechanic says, I'll report back when he lets me know.
 
#19 ·
I Recall Several Posts



This has never happened to me, but I read several posts where folks experienced no start conditions OUT OF THE BLUE, usually after a short trip to a store, or after dying on a highway(RealShepherd), and they attributed the no start/dying to the Voltage Regulator. I think sbaert had a post or two about this issue. The brushes seem to wear down between 100K and 150k? Thom is at 140K?

It sticks in my mind, because i would never want to experience such a calamity. :nono:
I have a spare VR now, and I checked the one in the vehicle to be damned certain this isn't going to fail and leave me sitting. The brushes appear to be at about 30-40% length @ 110K. :thumbsup:

I certainly agree that it's related to a poor charging/charged battery, and by checking the battery while running you get a good idea about the health of the VR, but the VR apparently WILL leave you sitting. I think the 1st symptom is a wonky radio, then other electrical systems begin to shut down. That is why I asked Thom about any abnormalities that he may have experienced.

I also recall a thread where a major ground terminal and/or a major positive terminal was corroded/eroded to a point where the contacts were extremely faulty. A good cleaning and the forum member was back on the road. I think moisture was the culprit in that circumstance.
 
#21 ·
I guarantee you could cut the serpentine belt off the car, and with a solid battery, it will start and stay running until the voltage from the battery drops to something in the range of 11.4v. Then systems start shutting down and shortly thereafter the engine dies.

Batteries start the car and then the alternator takes over and provides the voltage required to run the engine, recharge the battery as well as keep all onboard systems and accessories functional.
 
#22 ·
I guarantee you could cut the serpentine belt off the car, and with a solid battery, it will start and stay running until the voltage from the battery drops to something in the range of 11.4v.
Can confirm. Had my belt snap when my smog pump went bad a few years ago. I was close to my home so I restarted the car and limped it a few blocks back to my garage and had it towed out from there later in the day.
 
#24 ·
ahhhh, that "voltage regulator" you are speaking about. ok, to save my reputation if i have any, i was thinking about another voltage regulator, or maybe its name should be slightly different. now i cannot recall exactly, but i have learned that some older cars have it, and "newer" not. this is supported by the fact that it is in the electrical diagrams for older cars and it is missing in the diagrams for the newer ones. If my memory serves me well then in newer cars (which my is) that voltage regulator is incorporated into base module.

Thom_7, I read that SRS light can very rarely come on for about 1 or 2 minutes and it does not indicate any fault.
 
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