Help Need SLK R170, Heavy post

PAUL R

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Hi People, I really need some help please,
I have an early SLK R170, and have a starting issue, basically it won't start or even crank over.
History:
Drove the car out of our garage at home and parked on the drive for a couple of days, all was fine, (no issues before with anything) Come to put the car back into the garage it ran for a couple of yards, maybe feet, then cut out. Won't even turn over.
Me and the good lady pushed it back into it's now resting position.
Called the AA who got the car started after an hour fiddling and messing around the box that contains the K40 relay module, the box just by the battery.
He Said that if it fails again to call us as that's what we are paid for, also gave the offer of recovery to which ever nominated garage I chose.
As I do my own oil changes, I am out of touch with main dealer practices, and to my expense over the years I have stayed away from the due to cost and less than honest information. I have never used an independent garage.

I need either a good recommended auto electrician who is up to speed with Mercedes SLK R170 cars
Or personal input from experience gained, with this problem. so that I can rectify the problem myself with your help of course.

The Facts :
Key position 1 acc, on, (radio), no problems.
Key position 2 all dash lights show, and after 3 or 4 seconds SRS light go's out normal.
Key position 3 No start sequence initiated, no relay's trip in, no fuel pump buzzing, But main cooling fan runs at high velocity, (as this is default mode for a problem)
I am quite capable of rectifying most faults on my cars and have access to most tools, but I am quite all at sea with this one.

I have checked that there is power to the K40 relay box, which is what an internet search says is the most common fault, that causes this problem,
As the horn and air pump from the central locking is working. So there must be power to the relay circuits,
I can not check the other 3 relays as there in the box, the other 3 relays control stability control, fuel pump, and engine management.
I have had the K40 relay box out of the main box and checked for tracking on the circuits and nothing no furring of or burning of the soldered joints and all the relays move without any problems.
As this is an early car the immobiliser / alarm was dealer fit, I have dropped this out of the system and it has had no effect, and the alarm works fine.

Any Help or pointers to help me solve my problem will be gratefully received

Paul R
 

Steve@Avantgarde

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Your Mercedes
E300 Coupe AMG Line PP/NE, SLR McLaren Roadster, SL55 & C32AMG
The K40 relay is the common issue.

Basic diagnostics first though, do you have a spare key and tried it? have you checked the fault codes? Do you have 12v going to the starter motor?
 
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PAUL R

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Cheers for the reply, spare key : yes and tried, no change,..... No fault codes on OBDii via a 38 pin link up cable,.... and yes 12+v going to starter.
I have made in roads into the problem, I am going to re flow all joints on original K40 board tomorrow and if that fails change the resistors on the module.
Then if still no good change the K40 unit for a new one.

Paul
 
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PAUL R

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Steve, I have reflowed the joints, refitted, no change, went to change resistors, purchased the wrong ones from maplins, I got the silver and grey mixed up, so I had purchase the 2ohm ones instead of the 680ohm,(not much difference) so tomorrow I will just go and get a new K40, just a foot note, whilst the old K40 unit was fitted I manually closed the centre relay and fired the car up, and it ran until I removed the cocktail stick, so as you said, Common issue.
Thank you for your input, always nice to have a reply from a knowledgeable source
Paul
 
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PAUL R

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All sorted New K40 purchased and fitted, Thanks for the help
Paul
 

tony clark

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Your Mercedes
slk230/2003/2.3 auto
All sorted New K40 purchased and fitted, Thanks for the help
Paul
HELLO MATE
this sounds like my problem,where you'd buy your k40 relay from and how much are they,or a ballpark figure if you like,and whereabouts is it?
 


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