How do you know the battery is good? Have you had it load-tested?
It may still work the lights and relays etc, yet not have enough power to crank the engine.
First thing I would try is to jump-start the car from another.

 

I used my shops tester/charger. Also I used the quick start on it to try to start the car. No cranking even with the tester/charger.

 

Battery terminals clean and tight?
Power at the starter itself?

 

Sounds like the solenoid.

 

terminals are clean and tight. I don't know about power at the starter. It was all of a sudden. It cranked twice then the third time it stopped.

 

There are only a few devices in your starting circuit:

• battery
• starter & solenoid
• ignition switch
• starter relay
• transmisssion lockout switch
• connecting cables and wiring

You need to isolate the culprit in a logical fashion.
You say you are sure the battery is good, so the next step is to see whether power is actually reaching the starter when you turn the key. If it is then you have a starter or solenoid problem. If it is not, you have a problem in the upstream circuit.

Put a meter or test light on the starter terminals to check for 12v, while a helper turns the ignition switch key (or use a remote starter switch yourself). Alternatively, apply 12v from another source to the starter to see if it operates. OR run jumper cables directly from your battery to the starter. This will tell you whether your starter is the problem.

 

After your second attempt do the lights and other electrical equipment function?

My battery died recently, but in my case everything went dead. It ended up being a completely failed battery. When I ran an ohm meter from pole to pole it showed 10mV which is really zero.

Loren

 

Everything works except it won't crank.

 

I had the same trouble once. It turned out that I had bumped the shift lever out of Neutral into Reverse. I was trying for 2 days to shoot an electrical problem that was really my brain fart.

Sometimes you gotta check the simple things first.

 

Worth checking, but the OP reports the start relay is engaging.
The transmission lockout switch disables the starting relay, no?

 

Posting too fast earlier, sorry. The last two weeks have been pretty bad. I think I need to sleep for a week solid to try and catch up for the last few months. Between the equipment going up in smoke at one end of the state and a weird trouble in the opposite end, I've been doing a lot of overtime. Things are getting a bit fuzzy around the edges.

 

Posting too fast earlier, sorry.

Not necessarily, RT.
The transmission safety switch may prove to be the culprit after all, although I still suspect the battery or its cabling.
Let's hope the OP reports back......

 

Sometimes a starter can develop a bad spot in the brushes or a stuck solenoid. A friend got me going one time with a rap from a hammer on the starter housing, jarred it back into service.

 

Yup. Mine did that for a couple of weeks, until I could get it into the shop to have the starter changed.

 

You can check for 12VDC from the battery to the engine compartment at the junction box on the right fender. Look for the large gauge cables. Not likely but there could be a cable/connection problem there.

 

I think he disappeared.

 

I hate when that happens.
Makes you think you've wasted your time.

 

Hopefully didn't electrocute himself or something!

 

I didn't dissapear, was out of town. Just got a new solenoid today. I'm going to try it tonight or tomorrow. I'm definately not a novice at mechanics, just these crazy Mercedes. It's not the transmission lockout switch as the relay only works in nuetral and park. The relay is clicking when in the start position as I stated before. The solenoid is kind of difficult to get to in this car though, so I haven't checked to see if there's power there. I'm used to old Chevy's. This car leaves very little room under the hood or underneath. I've got power to everything else i.e. lights, radio, horn etc. Baterry IS good. Is it simple to drop the starter or possible to change the solenoid without dropping the starter?

 

..... I haven't checked to see if there's power there ....

Beats me why you'd buy or change anything until you isolate the problem.
At least check for power at the starter.

 

Just looked up removing starter... OUCH. Please tell me I can change the solenoid with out the whole top bolt fiasco!

 

I don't know this for a fact, but after seeing the R&R of my old starter, I would guess not.

And that leads me to suggest that, rather than just replacing the solenoid, replace the whole thing. This isn't a road you want to travel twice, and if the solenoid is burned, chances are the windings on the starter motor are going, too. Absolutely no point in going through all this pain and hassle, just so you can do it again in six months or a year.

 

i do not think you can swap the selenoid without removing the starter completely , maby im wrong here but i hope you could.

 

Before you remove the Starter, try taking a socket and breaker bar and see if you can rotate the engine by hand. Go back and forth, kinda like rocking it. It may be as simple as the starter bendix being hung up............

 

I went through a similar situation where starting went from sluggish to jumpable to not-even-jumpable within days.

W107 Non-starting Grief - ShopForum

I replaced the starter when I didn't need to. It turned out to be a weak battery ground cable.

You be the Judge: Is this cable Good or Bad? - ShopForum

 

Just got the new starter in. Cranks right up. I took the advice of replacing the whole thing as opposed to just the solenoid.