Car won't start! Help
 

Hey everyone,

Here's my problem.

Background
I went to my car this morning to go to work and opened the door, as always all doors unlocked. I got in the car and turned the key to start the car. At this point the dash lights turned on and as I continued to turn the key to start the engine, everything died immediately. Lights won't turn on at all and its as if the battery was completely dissconnected.

I had a friend try to jumpstart it and had zero success. Not even the lights or anything will show even the slightest sign of life when hooked up to another car. I checked the fuse box and everything seemed to be fine. I checked the connections on the battery and they were tight.

My battery is a red top Optima and has been great except for one time a few months ago when I left my stereo on for too long with car off.

Problem
Car is completely dead!

Find
Does anyone have any suggestions as to what to check?:nix:

hi - i am wondering if this is the first time your car has not been able to start?.....

1.have you check whether there is any electricity power in your car's battery?...you can use a battery tester to check the condition of your battery....because you did mentioned that the lights goes off....

2.have you check whether the battery terminals have come loose?....because your car seems to have a lack of electricity power from the battery.

3.finally, i would like to mention the OVP relay located behind your battery. This OVP replay has always been a problem for many mercedes W124....you can't really check whether your car OVP is operational....you can only get a good replacement....and then check whether there is any improvement....

Those are the areas which have come into my mind....because if your car was working and moving...only yesterday...what could have made your car to stop cranking?...

Battery doesn't seem to be the problem. It must be a relay or fuse since everything was fine for about 1 second...then everything died.

Terminals are tight and there is juice in battery.

I can try the OVP relay. Here is an article I found on it.

Based on that article. There is a fuse that could pop on it. So i'll try this out when I get home.

Any other words of wisdom from anyone?

The car will still start without an OVP. It will just be very rough because it runs without any computer assistance in open-loop.

Does the battery have voltage?

PS: Don't jump-start w124's. Its a sure way to blow the OVP so consider it a $50 boost each time. There are many MB statements on doing this.

You might want to check the voltage regulator on the alternator and see if its worn completely down.

Make sure your cables are not frayed to the battery too. The negative/ground cable over time will tend to lose contact with the ring. Just visually check it has a ground.

:rolf:
Battery's do go bad.. even though there is plenty of voltage if there is a dead cell in the battery it will act as though it is dead... just an fyi...

When you turn the key, and no light, no sound, nothing, that could be the starter. Well my acura was, I don't know about MB.

**UPDATE**
 

So I've narrowed down the problem of my car being 100% dead to the anti-theft system module. If I disconnect one of the connections, then try the car again, the car started and was then all systems were killed immediately after it fired.

Has anyone heard of these units going bad? It seems so random that it is doing this. I haven't been doing any work on the car in months besides changing the wheels, oil and putting gas in the tank!

False. If there is a dead cell, it will still show a lower than usual voltage. Each cell is 2v, so if you are getting 10v according to a DMM, you know a cell is dead, or is no longer as strong as it was new. You will never get a 12v reading if a cell is dead or weak.

Glad to hear you found the culprit though.

**Solution***
 

Well....it was really easy:smash:

After having the shop take a look at my car. They determined that the problem was dirty connections at the power junction distribution block that is the first stop from the wire coming off the battery. This is quite frustrating after all the time I spent troubleshooting.

In addition, they fixed my blower motor that wasn't working. It was a fuse...so frustrating. I didn't know the fuse was separate from the fuse box. It is right next to the hood sensor switch and is covered by a black plastic door.

But at least I'm back on the road:zoom:

Live and learn:wall:

I had an issue with my car where i would blow a fuse sometimes when i closed my door, that fuse was somehow tied to the anti-theft system so my engine would not start so i would have to get out f the car and replace the fuse, one time it even set off the alarm while i was driving after i turned on the radio

The problem ended up being a short in one of my doors