Slk200 Starter wont engage.(2003)

[Steve Magee]

Hi folks this is my post . I have a 2003 SLK200 auto. its been sitting over the winter. It was last used in November. I was returning from a short journey ,when I got in the car it didn't want to start kept cranking over . it eventually started in went into limp mode. Drove home turned out to be a speed sensor ( generic obd reader doesn't say which one ). the following day didn't want to crank over at all. Checked all the obvious things like earth straps etc. no joy so I left it over winter.

Im trying to sort it now the weather is starting to perk up. I have reset the fault codes and its currently not showing a wheel sensor fault .However It wont go into gear ( the classic brake switch fault ?)

I have taken the lid off the box containing all the electronic bits , to my surprise it was quite wet !!!

got rid of all the wetness and moist . took out the k40 box hoping for some dodgy solder but it looks in very good condition the only components on the board are a few resisters and a diode. the diode is ok (metered). fuses ok. Relays move as they should. Even though its not showing a faulty speed sensor if this was still an issue would it inhibit the starter motor, if the you move the interlock to neutral it still wont start. oh i've also flicked the central locking on and off a couple of times just in case it might have been some quirk with the key.

I supposed it could be a knackered starter motor, if you stick a meter on the battery and turn the key its not drawing any current. Is there a way to check the feed to the starter from up top ? I don't mind having a go if someone could put me in the right direction. This car was super reliable until it wasn't

Many Thanks

Steve [Mold, North Walles ]

 

[Steve Magee]

forgot to mention the fuel pumps sounds like it spools up.

 

[Blobcat]

Hello and welcome

Wales is nice, it just needs a roof...

Which is probably why you’re suffering electrickery issues. I’m presuming your battery is in perfect condition as that’s where I’d be starting.

I’d then go for the water leaks and ensure none of the connectors have corroded.

 

[Steve Magee]

the battery is fine , like I said when the key is engaged its not drawing any current at all. If the doors lock with the key I assume its not a key syncing issue ?

 

[noonboots]

Put a 12v feed onto the small terminal on the starter solenoid. It should engage straight away and turn over the engine. If it does you have lost the feed to the starter from the start relay. If not the starter needs looking at.

 

[Oldspanners]

the battery is fine , like I said when the key is engaged its not drawing any current at all. If the doors lock with the key I assume its not a key syncing issue ?

You need to get a meter on the feed to the starter and check that you are getting voltage there, if so then it's the starter motor as if you say there is no current draw on the battery.
The earth to the engine needs to be checked not just visually but by giving it a good pull and if in doubt take it off and clean the mating surfaces.
Check all the drains around the windscreen are not blocked or restricted.
I can't see a speed sensor preventing it starting.
Failing that get a icarsoft or a Star to check things over.

 

[Steve Magee]

Pretty sure the connectors shouldn't be white inside !!!!!!
That said I'm still getting voltage so don't think its the problem. ill clean them all and check the k40 relays all activate tomorrow.

 

[Steve Magee]

I have news...…
the gearbox wont come out of park without manually releasing the interlock. what I didn't realise was when releasing the interlock and moving the selector up and down it doesn't show the gear on the lcd display.
But at some point during the proceedings it will suddenly show the gear in the display. When it does the engine will turn over. Prior to giving up for the evening the selector issue seemed to have sorted itself. Took ages for the engine to turn over I suspect the fuel filter wants changing because it hasn't run for over 6 months, ill do it tomorrow.
Now getting back to the original fault, when the engine ran the ABS light came on again which was the original fault.
I'll see if I can get a brake switch tomorrow as well. Im wondering if the speed sensor issue is messing with the gearbox ?
As my code reader wont tell me which sensor it is I suppose I'll have to take them all off and inspect them.
I will report back tomorrow.

 

[LostKiwi]

This sounds like an ESL issue. Until the engine knows the car is in P or N it won't start. It won't be the speed sensors.

 

[Steve Magee]

back to square one again, took it for a spin around the block this morning all ok, when it was outside the house ticking over the abs and esp light came on the lcd that displays the gears went back to a solid square ( stopped showing the gear ) and the shifter locked out again.
Om my generic reader the only fault it shows is a speed sensor. I tried to remove the rear right one to check its condition and its rusted. ****** stupid idea using torx. Anyway decided not going to do anything else until I have a Mercedes specific code reader.
The icarsoft 980 will do the trick, can anyone recommend anything similar around the same price.

Thanks.

 

[LostKiwi]

This definitely sounds like an ESL fault.
You're doing the right thing using a proper reader that will read more modules.

 

[Steve Magee]

What' s strange when the speed sensor fault cleared and I drove it this morning, It was showing the gears in the display. when I abs esp light came on I actually saw the gear selector change to a solid block at the same time.

 

[Oldspanners]

What' s strange when the speed sensor fault cleared and I drove it this morning, It was showing the gears in the display. when I abs esp light came on I actually saw the gear selector change to a solid block at the same time.

View attachment 50224

If you've had water in the electronics all sorts of issues can appear, have a look at all the areas and connectors that may have been wet.

 

[Uncle Benz]

Sounds like a gear selector module fault to me, although I'd be tempted to have a look at the brake pedal switch first. I've seen one a while back with a similar start issue, but two or three hard stamps on the pedal would see it come back to life. I still don't understand how the brake switch links to the starter though!

 

[Steve Magee]

forgot to mention it will still only let me remove the key when its in park.

where is the selector module located on the R170
Thanks.

 

[Uncle Benz]

The selector module is the gear lever assembly. Whole bit.

Key will only remove in park. That's normal

Is your brake pedal returning fully up when you release it? The plastic pivot pin is known to get stiff and prevent the pedal fully rising, therefore not operating the brake switch correctly and confusing the system. Again, not hugely common, but I've seen a few

 

[Steve Magee]

Hi, Thanks for the info , yes I appreciate the key will only come out in park, my point was although its not displaying gears on the select lcd it must know its in park from the key to come out. I assume this is some sort of mechanical stop not connected with the select module.
Easy things first I've ordered a break switch and a code reader.

Cheers

Steve

 

[Uncle Benz]

Yes, purely mechanical. There is a cable between the two that releases the key