Car will not start

It's definitely not that sensor. I originally thought it was the pilot bushing after looking up many different websites with the same symptoms so I changed it and that didn't fix it. Then I realized that it wasn't showing any gear indicator on the LCD dash. When turning the key on it showed the S blocked out in yellow instead of P. I know if the car doesn't detect that it's in P it will not start. So I then researched this and found that people said the shift module inside the shifter can do this causing it not to register that it's in park. So I bought a used one from a salvage yard and still the same issue. Just earlier after two days of not starting or even trying too I decided to screw around with the relays. I pulled the K (AT relay) and S (starter relay) and swapped them around and when I did that I went inside and turned the key on and the P registered so I thought I had it. I tried to start the car and it seemed like it was trying to turn over but not enough juice in the battery like something was draining the battery. So as of right now, I have a battery charger on the car and soon I'll go give it a shot again and see what happens.

No, I've never changed that sensor before because it's never been a thought in my mind. A Mercedes pilot bushing goes inside the transmission it's where the 13-pin connector plugs into the transmission. It's a known issue where the o ring goes bad and it leaks oil into the connector shorting out the transmission harness and making the TCU stop the car from starting or shifting correctly. I've never had any issues at all with the motor running well. When it starts and runs it runs excellent the only issues I've had were always pertaining to the transmission. Going down the road and losing the speedometer and the transmission locking into one gear which is limp mode then getting it home turning it off and then it won't start again till the next day. I didn't realize till recently the reason why it wasn't starting is that the gear indication light wasn't showing the transmission in Park. If you looked on the dash you'd see no gear selected. I've uploaded an image to show you want I mean. Well, today I swapped the two relays mentioned earlier around and the gear indicator started working again it shows P when I turn on the key now where for two days it didn't. I've already checked the TCU it looks brand new inside and out all connectors look great and the ECU looks great too all looks brand new I've already checked both of those weeks ago and again recently. Photos attached of the TCU. ECU looks just as good all connections super clean and no damage inside. I just don't have any images of the ECU.

I want to mention though that the gear indicator is now working it shows P when I turn on the key so that part of the issue is fixed the issue I'm having now is it's still not starting when I turn the key the dash lights all come on all that good stuff but when I turn the key I get nothing at all. It doesn't even crank over. I feel like its the starter relay since I swapped those relays around.

I ordered a multi-meter on Amazon I'll have it tomorrow so I can do some more testing. Right now the car still won't start when turning the key I get nothing. I tried to jump the starter relay earlier today with a paperclip with the key turned on and it sparked a tiny bit but the starter never engaged. What's weird is I've never had any issues with the starter. It has always started the car has never sounded like it was going out or made any weird noises. With the jumper not engaging the starter, it's making me think that the starter went bad. I'm a little upset after researching where the starter is located on this car to find out that it's behind heat shields that are behind the exhaust and in order to even see the starter you have to pull the entire exhaust off and all the heat shields behind it. I wanted to tap on the starter and see if I could get it engaged to see if it has some bad brushes or something but there is no way to access it from the top or bottom which is absolutely ignorant!

There is no way to see if the starter is getting power without pulling the whole exhaust pipes off you have to drop it from the motor and behind both of the cats and pull that entire part of the exhaust off to even see the starter to attempt something like that.

You have the wrong diagram for my car the stater fuse for my car is #52 the #50 fuse is for mass air flow, light switch module, etc. Here is the diagram for my car's front SAM:

https://www.dropbox.com/s/b59nr0v9t35bny2/FrontFuses.pdf?dl=0

Okay, so I ran a wire to the battery and touched it on #50 fuse and it sparked a little but no starter engagement at all. I don't know how the stater just magically went out when it has been starting this car with no issues for months but I guess it happens. That's one heck of a freaking job to change out a starter. I don't know what else it could be if I can't get it to engage then it has to be bad. You can do the same thing by jumping the starter relay which is what I tried yesterday and it sparked a little too but I couldn't get it to engage the starter either. The engine is definitely not locked up I don't need to check that at all. This engine runs flawlessly when it's actually running. If you have any more suggestions I'd like to hear them before I go try and buy and replace this starter. This is going to be an act of nature to remove this starter I don't know anyone who has a lift to put this car on which is really what is needed to do this job I need to get all four wheels off the ground as high as I can in order to remove the exhaust. Without removing the exhaust I can't access the starter at all. I wish this had been one of the Mercedes where the starter was under the intake manifold I'd be much happier right now.

According to the WIS I bought off eBay looking up the repair for the starter in the manual for my car it says to remove the exhaust to even get to it. Then behind that is heat shields that need to be removed and you need a long extension to even reach the bolts. Doing that while underneath the car sounds like a nightmare I'm not even sure I can do it and I surely can't afford to pay someone $1,000.00 to replace the stupid starter in this car. I dunno what to do at this point.

Does the car have a neutral safety switch that could possibly stop the relay and fuse from getting any power? I mean that doesn't seem like it would matter when you are jumping the relay and starter manually with a hot wire. I just need to know for certain that it's the starter before I go out of my way trying to rip the exhaust out of my car just to see the starter and get it out and test it. I don't want to go through all that unless I know for 100% fact it has something to do with the starter itself.

I'd much rather it be under the intake it's not that big of a job to pull the intake off at least you don't have to climb under the car to do the job. So I need to try and jump that fuse #50?

I've already tried to jump to the #52 fuse and it sparks a little when I touch the wire from the battery but it doesn't do anything at all. It doesn't even try and I can't hear anything happen when I touch that hot wire to the SAM.

#50 fuse is only a 5 amp fuse so there is just no way that is the correct fuse to jump. Ah, you said it shows circuit 50 but the fuse is #52 gotcha. I did that already and got nothing just a little spark and nothing otherwise.

Okay, so I thought I didn't have my hot wire tester and I found it just earlier. I ordered a multi meter which will be here later today so I haven't had a chance to do any testing as I wanted to. So I tested the #52 fuse and I'm getting no power to either side of the fuse it's dead. The fuse is fine. So I have eliminated the starter as being the issue it's in the handshake done by the ECU. So where do you think I should start next?

I tried that I hooked a wire from the battery positive and touched it to the upper side of the fuse holder on the SAM and it sparked a little but no engagement on the starter. When I had the hot wire tester hooked up all the fuses on that whole side of the panel was hot except for that fuse. I tested all fuses in the whole box and everything is hot but the starter fuse. I tried to jump wire to the fuse and still nothing. All this done with the key in the second position.

I've already pulled the starter relay and put a jumper between 3 and 5 which should be 30 and 87 on the SAM or whatever and turned the key on and no engagement on the starter once again. Both the relay and the fuse jumper didn't get the starter to turn over. Picture of relay attached.

When I jumped the relay and then tried to jump the fuse after I used a cable TV wire for the jumper it seemed plenty big enough to at least do test pictures attached.

I have an Autel MD808 Elite but when I scan with it the only codes it tells me are there or were before I deleted them was

P2017-1
Self-adaption of mixture

P20CC-8
Rough road detection

the second one is because I need to replace the passenger side ABS speed sensor it was rubbing the tire and half the wires are showing just haven't got around to doing that yet. The other one I've ignored for right now since it shouldn't cause the car not to start. I don't know anyone with a DAS and honestly, if I spend money to have it scanned with a DAS I'll have no money left to work on the car. I'm super low on money I was hoping to get this thing running with a couple of hundred dollars I have leftover for my budget on this car.

I turned the key to 2 positions and tested if it was hot and then I didn't get anything so then I sat the tester up so I could see it and I reached inside the car and turned the key as if I was going to start the car and still no power to the fuse on either say. I tested it both ways encase the key needed to be turned.

EDIT: So I went outside with my mom and had her turn the key to try and start the car and the fuse is hot on both sides. Maybe because of me leaning the tester to the side it wasn't making a good connection for me. I did test it and I hear the relay click and I have fire at both sides of fuse #52 so I guess we are back to the starter being the culprit.