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Discussion Starter · #1 ·
Our SLK 200 auto 2004 spends a lot of time parked up and has developed several faults of the last couple of years which have I've resolved by searching this site.

The car will not start but if I explain the status quo, the problem may be obvious to an experienced member.

Currently when the ignition is turned on everything lights up but there is no click. I can return to the car a day later and it will fire up perfectly and run UNTIL the 'D' for drive or whatever is selected blanks out on the dashboard. The car will continue running but when placed in park, locks in 'P'. If Park is released by the screwdriver method the gear shifts angrily into drive or reverse and stays in the low gear limp home mode.

This routine happens a lot so as soon as I see the GEAR SELCTION NOT SHOWING ON THE DASH the circuit is shut down ABS EPS appears at the same time. The car has not started now for a week.

Battery is excellent
Brake switch has been replaced
K40 board is fine.

I have noticed the ATF level is below the minimum!

Any suggestions would be greatly appreciated.
 

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2001 SLK320
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being a bit sybil fawlty, but

when you say the Auto trans fluid is below level, is that from cold? there are two marking schemes on the dipstick, one for cold at 20deg Celsius, the other for normal, at 80 deg Celsius.
Are you using the factory part dipstick? My 2001 ( and all my other similarly gearboxed MB's) doesn't have a dipstick, so I had to buy the workshop part from Mercedes.

If you don't have the correct one, you can make one from curtain rod. I'm sure there is a how to on here.

Any road up, if you haven't enough fluid in the box, that really might be the cause of the problem.
 

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Discussion Starter · #3 ·
Thank you for your prompt reply.

I purchased the dipstick after the car last fired up so I can only take the reading from cold. The level doesn't reach the lower minimum (cold) mark on the dipstick. Do you know then if there's a fail save sensor or switch which stops the engine turning if the ATF level is low and would this also stop the gear selection display on the dashboard?
 

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2001 SLK320
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I can't see much in the manual/handbook

other than " go to a Mercedes dealer".

try this search strand

http://www.slkworld.com/slk-r170-ge...ssion-stuck-limp-home-mode-after-service.html

there are other similar threads here.

I do know that the fluid will barely register on the dipstick when cold, even if the level is spot on. I have been training myself to try and equate the two for the last 8 years with little success. 80 deg is really the only accurate measurement, subject to level and having pumped the fluid through all the gear selections for a good few minutes beforehand
 

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Discussion Starter · #5 ·
The auto gear section e.g. 'P' (park), 'N' (neutral) etc has stopped showing on the dashboard. When this happens the engine will not start.. SLK 200 2004. Any suggestions please
 

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Registered 2002 SLK320
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Having read through this properly some other suggestions.
The selector module could be failing and losing communication with the dash, explaining why there is sometimes no display.
The pilot bush on the gearbox could be leaking/wicking transmission fluid into the gearbox ECU. Have a look underneath towards the front of the gearbox there is a connector to the pilot bush, is it dry around there? Pull the connector off and see if there is fluid inside it. This can travel up the wiring loom into the ECU. The ECU is under the N/S floor. Pull up the carpet and have a look.
A cranking voltage of less than 10V will also through up errors, give the battery a good charge.

Getting it plugged in and the fault codes read is the way forward. HTH
 

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Discussion Starter · #10 ·
Thank you for your advice. The battery is a year old and kept pretty much on a trickle charge; although reading fully charged I will check the voltage. I will also check the pilot bush which I assume is not the electrical connector to be found just above the left front (viewed front of car) of the gearbox sump?

The car suffers a lot from dampness/condensation; I picked up that the gear shift assembly module (under the shifter) sits on the floor pan and can possibly suffer from damp/oxidation. Is this selector module?

All said and done I will get the codes read assuming these can be read from ignition turned on as the car won't start.
 

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**Registered 2009 SLK200
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Thank you for your advice. The battery is a year old and kept pretty much on a trickle charge; although reading fully charged I will check the voltage. I will also check the pilot bush which I assume is not the electrical connector to be found just above the left front (viewed front of car) of the gearbox sump?

The car suffers a lot from dampness/condensation; I picked up that the gear shift assembly module (under the shifter) sits on the floor pan and can possibly suffer from damp/oxidation. Is this selector module?

All said and done I will get the codes read assuming these can be read from ignition turned on as the car won't start.
Car wont need to run to read / clear codes on your 170 :smile:
As long as ignition is on all fine .
 

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Registered 2002 SLK320
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The speed sensor won't stop the car starting. The communication link could be the selector module/gear selector. I would check for dampness in the passenger footwell and the gearbox ECU. The pilot bush is on the L/H side of the gearbox towards the front. There is only 1 connector from memory.
 

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Registered 2002 SLK320
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I would also check the drains as they could be blocked and causing damp. At the front they are in the corner of each wing by the scuttle. Pour some water down there and see if it comes out just behind each front wheel.
It's also worth taking the cover behind the glove box out and looking at the pollen filter. The filter box can fill up with debris and water. There are how to's on YouTube.
The two drains for the rear are under the back edge of the boot each side where it meets the roof. You can see the plastic mesh covers, again pour some water down there and see if it comes out by the rear wheels.
 

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Discussion Starter · #16 ·
OK; I removed the electrical connector (pilot bush?) on the front left of the gear box and it is quite damp with ATF. There is no seepage around this connector , - the sump is dry. Can I flush this connector with white spirit, dry and reconnect?

I lifted the plate holding the ECU etc from under the carpet on the new side floor. This whole zone is dry and pristine much as it left the factory. Would unplugging and re-plugging the connectors in this area to clear any oxidisation help?

My gut tells me I need to explore the selector module/gear selector. Please can you throw a little more light on this; location etc. Thank you.
 

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Discussion Starter · #18 ·
Having exposed the gear selector module on my 2004 SLK 170 it appears to have different features to the standard early 170s. Being it was the last year of manufacture could this be a 171 selector? The circuit boards seem serviceable also instead of the 4 x bolts and two screws to release the unit there are an additional 3 x bolts which secure the shifter to the floor at the same time - once removed- allow the plastic cover to lift from the main unit. It gives me the impression it's an upgrade?

Please take a look at these photos. Many thanks.
 

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