Yeah...it's a keeper. The post that is. Thanks Bazzle!

 

WOW! Even though I'm not a R170 owner, I like to read the how-to stuff just for general knowledge. Thanks Bazzle. Y)

 

So was there a cold solder joint there? I don't see one. Or was the picture totally to show how to get to it?

 

Just for you Mtiede :bannana:

Bazzle

 

More good info from Bazzle!!!

Hope I never have to do this. Yikes!

SLKman:tu:

 

More good info from Bazzle!!!

Hope I never have to do this. Yikes!

SLKman:tu:

For some its fun! The best part of the troubleshooting procedure. For bench technicians, soldering is like...landing for pilots. Oh wait...I get to do both...woohoo!! :rb

 

Hey Bazzle thanks for the post.
I had trouble starting my 2000 SLK 230 yesterday. When I turned the key to start, I got all the idiot lights and the radiator cooling fan was running in high speed. The engine was warm but not hot. The car did not crank the starting motor at all. I checked and it did not set the check engine lightl. A couple hours later I tryed to start the car and it started right up normally. I thought that the problem might be in the ignition switch or the starting motor/soleniod.
I found your post and decided that I better check it to see if that was the problem. Did you figure out what the cold solder joint controlled?
I took pictures of mine and they look identical to the pics that you posted. SO this problem is not unique to your car. If that is not the problem I will pull the starter/soleniod and then check it. There was no noise except for the radiator fan when I tryed to start it.

 

trouble starting my 2000 SLK 230



I seem to have the same problem. It all started after I received a shock from starting the car. It left a burn mark the size of a pin on my fingernail. Ever since, I have had the issue with the 230 not starting right away and or cutting off completely after putting it in gear.


I am going to look at the K40 to see if there are any obvious cracks to solder.

 

My 1999 SLK230 Has Had A Rough Idle For A WHILE Now, More So In Reverse. Dealers Have Said It Was JUST A Vacuum Leak And Could Never Narrow It Down/Too Many Vacuum Lines. Car Has Also Died Out A Few Times And Wouldn't Even Crank Over After It Dies Out. The Car Failed Emissions Test Last Month. The Codes Showed A Throttle Position Switch Learned Open/Replaced That No Luck. A Fuel Pump Circuit High and Secondary Air Valve Code, And Many Other Pending Codes. I Don't Trust Any Of The Local BMW/Mercedes Dealers In My Area. They've Lied And Taken Me To The Bank Before. I Usually Fix My Own Cars But This One Stumped Me. I Didn't Want To Throw Parts At It. Today I Took It To My Local Private Shop I Know And They Said It's Probably The K40 Relay. Just Like The Post Said. I'll See If It Works.

 

Happy Holidays everyone!

If your SLK230 is over 5 years old, it would be WELL worth the $170.00 US to just replace the relay unit as a preventive measure. The part is not that expensive and it's a cake walk to change out. No one likes to be stranded miles away from home! PLUS, it may take your dealer time to order one. You will be down for that long. I lucked out and got the LAST ONE my dealer had!

REMEMBER: A smart one learns their own lessons, a wise one learns lessons through the lessons of others, and not-so-smart one NEVER learn any lessons...

'Tis the season to be a "wise one", isn't it? Hehe

 

Thanks Bazzle I like DIY's.

 

Thanks for sharing your knowledge Bazzle. Also a big thanks for taking the time to document with pictures.


:Beer:

 

My 1998 slk230 just started symptoms of k40 relay issues. The dash lights come on and when I press the throttle, the engine does not respond although it is still running. Then, the dash lights go out and everything is back to normal. Just had the Benz dealer diagnose and they said it is a bad k40 relay. I checked the k40 relay board described in previous posts, and the soder points are clean and solid. Is the actual k40 relay on the other side of the engine compartment(drivers side)? The sealer also had "discs" listed under parts. Not sure what that is. Anyone have any knowledge of replacing the k40 relay itself, and what "discs" are in relation to the k40?

 

K40 relay or K40 relay module?

Just searched the net for a k40 relay for my 98 slk230. I found what appears to be a k40 relay, but not the k40 relay module described in previous posts. Both part suppliers said it is located "right front under hood", but I don't see anything that looks like the picture on their site. Does anyone know anything about the k40 relay itself and where it is located? Or do I need to just be concerned about replacing the k40 relay module described in the previous posts?
http://www.autopartswarehouse.com/search/?N=11245+1668+4294967269+5866

 

Does any one have the diagram of the K40 realy board? I need to find out which realy is feeding the fuel pump to install an additional relay to cut it off!
Thanks

 

Does anyone know if the K40 controlls Spark, Starter or coil packs?

 

I have found that this relay board is responsible for 2 failures for my mercedes



1. Check engine light error codes -

p1235, p1236, p1420, p1525 (Rightmost circle in attached image)​

2. Failure to crank - intermittently (Center circle in attached image)​

I am including the close up from another post showing the bad soldering points. Make sure that you solder all 3​

 

i have a 1998 slk 230 kompresor and it dosnt crank but the soldering is perfect do you know what it could be?

 

Just want to add my .02 on this K40 relay...I have a 2000 SLK that my daughter drives away at college...She called and states the car would have low power at times and the check engine light would come on at times...I'm in the automotive repair field and called the local MB repair shop for estimate of diagnosic after pulling the codes...They wanted $850 to $1500 because they stated by the time they got the car that far apart to find the issue...After joining SLKWorld and doing a search I found this wonderful article and inspected the car myself...15-20 minutes later I see the burnt soldier joints and resoldiered, fixed and the cost was zero!!!! Bazzle was right on... Codes were P1525, P1235, P1236, and P1420 in that order...

 

Thanks Bazzle!

Fixed my engine starter problems, exact same symptoms as millerpm in:
http://www.mercedesforum.com/m_103131/tm.htm

I owe ya!

:tu:

 

K 40 issue resolved

Bazzle,

Thanks for the information regarding the K 40 relay. My 1999 SLK 230 lost power last week. I found your informative repair notes. I purchased a new K40 relay for $157.00 USD, installed it and the SLK is back in full power. Thanks!

Early SLKs suffered from soldered joint failures on the K40 pcb. This mainly affects smooth op and fuel pump.

I have just repaired mine.

K40 Relay - Right hand drive

LHD opposite

Remove neg batt term
Remove computer lid
Unclip holding tang and lift up module
Pull off connectors
Open case of module
Inspect soldered joints for cracks, overheating, dry joint etc
An eyeglass may help (top left hand group of three)
Remove old solder and resolder with new
Replace module
Push on connectors
Remove and replace 40A fuse to wipe the contacts.
Replacelid
Replace neg batt terminal.
Start car

Redo radio code if required.

more: http://www.benzworld.org/forums/r170...ssociated.html

Bazzle

 

Hi Guys, I am going to say that my SLK 230K 1998 has been in to Mercedes 3 times and they have had it over 2 weeks and in total i think i have spent well over £600 (lab and parts) to have this issue with intermittent starting and stopping fixed. First they said there was chafing of some cable on the undercarriage then changing the fuel pump. At no time have they mentioned this. I am furious. If i can find this on teh internet then why couldnt MB dealer (MB UK themselves) sort this out. It has been over 2 years and i have hardly driven the car 100 miles since (luckily it is a weekend or fun car). I am just about to see if i can repair this my self and if it is the problem, If it is i will be contacting MB and giving them a real earfull. Thank you Bazzle. I've had the car from new and its only done 32,000miles.

Thanks and let you know how i get on.

Not respinding to Bazzle's solution. Fan keeps running!

Hi again,

Well i have checked out the k40 relay circut board as per Bazzles instructions. The three little soldered bits in the corner look fine no degredation at all, cant see any anywhere else either so have not touched teh soldering iron. I gave it a good blow and cleaned the 40A fuse and put it back in. I have tried re-starting it but cant get it to turn over.

My symptoms are exactly as described by Millerpim on the other thread ->

millerpim

Join Date: May 2008
Posts: 1

2000 SLK Ignition Troubles & Died at Light
For the past several months, when I turn the key in the ignition to start the car, nothing happens. No noise. No engagement. After 2 or 3 tries, which involve removing the key and reinserting it, it will engage and start. Yesterday, I ended up cranking the key 50 times or more before it finally started. Today, it fired right up, but after driving for 20 minutes and sitting at a light, it suddenly died while in drive. I put it in park and tried to start it. It did not start. After a couple minutes of fidgeting with the key and turning it over and over, it finally started. What could cause this?

In addition my problem seems to be that if i turn the key to position 2, the fan comes on immediately (even on a cold start) and keeps spinning at high speed nothing else happens if i try and turn to ignition no sound of it trying to turn over or anything.


--------------------------------------
Prab again -------> So having had a look at the circuit board and it looking ok. Is there anything else anyone can reccomend. I have lost faith with the dealers and just want to get her up and running again. Sicne i took the module out she has not started again but that was only 30 mins ago will try her again later.

HELP! Anyone? Much appreciated.

 

Hey Prabo - have you read the codes from the car? Would be interesting to see what it's throwing out...

 

By the fan, do you mean the heating/cooling fan in the cabin? If so, that's another issue and seperate from the other problems, but I know the fix. Give me a bit more info about that...

 

Big fan behind the front grill of car. :-~

Big thanks guys.

1) Sorry no idea how to read the codes on the car. Do i need to take it to MB for that? Would be great to do it though.

2) By the fan i mean the Fan behind the radiator grill (radiator fan i guess)- the big round one that sits between the engine and just behind the grill at the front of the car. The fans inside the car used to come on when it first used to stall whilst driving (if the vents were on). But now when it fails to start or when it does stop whilst driving it is just this big fan under the bonnet.

Any help would be appreciated. Thanks for your time.

P

 

Did the fan go "crazy" after you checked the main board?
If so you should double check the connections. If the fan control (N76) http://www.buellwinkle.com/r170/comn76.htm doesn't get a signal when you turn on the igition the fan goes into a emergency mode. If connections ARE ok, you could have a problem with your AC control.

 

Intermittent failure to start

Dear Gabus,

Thank you. I checked the N76 - The connections appear ok - not sure on each cable though but the main block that goes in seemed fine. The fan is still going crazy but sometimes i can start it ok and the fan is fine and then 10 minutes later or another time i can try and start it and nothing happens except the fan going at high speed behind the radiator grill.

How do i check the codes? And what would be the first thing to replace given the above or should i trust Mercedes Benz again with it (again).

 

Thanks Gabus. Will take a look in teh morning is dark now. The fan has always gone crazy whenever the car suddenly stops or if i start it and it starts and stops or if it just does not turn over, eitehr way it suddenly comes on and teh fan keeps going. Then a few minutes or sometimes a day later i can start it and suddenly it works again for a while and then at some random time it all happens again.

The day i put the module back in it would not start at all (Coincidence i think) i could not see any broken solder it looked smooth and intact on the 3 connections mentioned by bazzle. But today 4 days later it suddenly started 6 times (i have not drvien it yet) and runs at standstill fine. Will take it out tommorow - fingers crossed. After i check the AC control N76.

ANy other ideas? Can i read the codes myself? How? Really need to get her out and make the most of the little sun we are likely to get this year.

Oh and also the roof is not folding down the switch lights up if i push in teh close direction but the open direction nothing happens no light flashing or anything? The car has not been drvien since last October. really should have taken her out more if it wasnt for this intermittent starting and driving problem. :-(

Thanks all,

 

wow!! just worked for me... thanks bazzle!!

took it to a merc dealer in sydney twice and they couldn't find the issue... but working well now thanks to you!

 

I wanted to thank this thread! I was getting some codes, checked this thread... went in expecting to do some soldering and found out one of the 5 15 amp fuses had blown. I replaced it and ol' murky is back to her original prowess. No codes!!

Thanks!