Mercedes SLK World banner

1 - 20 of 50 Posts

·
Registered 1998 SLK230
Joined
·
34 Posts
Discussion Starter #1
‘98 SLK 230
Here’s the story in case someone’s had the same issue:

CEL and sluggish performance, took the car to an independent shop near where I was staying (out of town), they said they couldn’t make sense of the codes (indicated instrument cluster problem?), they tested and replaced battery and alternator, still CEL, discovered K40 #2 fuse out, they replaced and done. Car ran great for a day or two, then CEL back with sluggish acceleration.

Drove the car 200 miles back home, researched the issue and replaced the K40 hoping to solve the problem. #2 fuse still fails every drive.
someone in another thread had this issue and replaced the main 50 amp fan fuse, but mine is in the main fuse compartment and good, but I haven’t seen fan come on.

Just drove the car to Autozone to check codes:
P1420 Air pump switch over valve
P0446 Evap Emission System vent control
P0443 Evap purge control valve
P1525 RH Adjustable camshaft timing solenoid
P0806 Clutch position sensor
P0135 O2 heater bank1, sensor 1
P0141 O2 heater bank1, sensor 2
 

·
Super Moderator UK 2002 SLK320 Blue
Joined
·
2,759 Posts
In the words of Deep Thought, from Hitch Hikers Guide to the Galaxy .... Tricky. o_O

f2 on the K40 is part of relay K9's circuitry and feeds what MB call the "Motor 87 M1/M2 relay". There are two outputs from the K40 from fuse 2.
On the diagram I have one feeds the following via Z7/6:
  • purge control valve, Y58/1
  • charcoal filter cut-off valve Y58/4
  • O2 sensor 1 (Upstream)
  • O2 sensor 2 (Downstream)
The other is another connector - Z7/36
  • Camshaft Hall sensor
  • Hot film MAF sensor
  • Air pump switchover valve
  • Adjustable camshaft timing solenoid
It also feeds N48 - BAS control module

Looking at your fault codes this issue would cause many of the faults listed above. I wonder if it is worth looking for a chafed or damaged wire in each of these elements and seeing if any have the potential to short to ground? Just a thought.
 

·
Registered
Joined
·
120 Posts
‘98 SLK 230
Here’s the story in case someone’s had the same issue:

CEL and sluggish performance, took the car to an independent shop near where I was staying (out of town), they said they couldn’t make sense of the codes (indicated instrument cluster problem?), they tested and replaced battery and alternator, still CEL, discovered K40 #2 fuse out, they replaced and done. Car ran great for a day or two, then CEL back with sluggish acceleration.

Drove the car 200 miles back home, researched the issue and replaced the K40 hoping to solve the problem. #2 fuse still fails every drive.
someone in another thread had this issue and replaced the main 50 amp fan fuse, but mine is in the main fuse compartment and good, but I haven’t seen fan come on.

Just drove the car to Autozone to check codes:
P1420 Air pump switch over valve
P0446 Evap Emission System vent control
P0443 Evap purge control valve
P1525 RH Adjustable camshaft timing solenoid
P0806 Clutch position sensor
P0135 O2 heater bank1, sensor 1
P0141 O2 heater bank1, sensor 2
Just replied to your message, for the benefit of others / to open discussion this was my response..

My SLK was an early one and the supercharger had the big pulley on the front with the electro-magnetic clutch on it.
My supercharger was not kicking in and I think this was because the electro-magnetic clutch had failed / shorted.
I decided to change the supercharger for a used one and that resolved the problem - power came back and fuse no longer blew.
I think you can test this theory by unplugging the supercharger, going for a drive and seeing if your fuse still blows. If you don't feel any difference in performance whilst it's unplugged you will also know your supercharger wasn't working as it should have been.
Even when parked up if you rev the car using the throttle cable past 2,500 odd rpm you should see the face of the supercharger clutch engage and start spinning very fast.
 

·
Registered 1998 SLK230
Joined
·
34 Posts
Discussion Starter #5
Thanks to all for the replies.

Forgot to include that the out-of-town shop found the following 5 (had told me there were 5 but the receipt states only 4, I remember him mentioning O2 sensor and engine timing) codes after replacing battery and alternator:

Air injection switch over valve
Camshaft position sensor
Purge control valve
Instrument cluster fault

Probably wouldn’t hurt to replace a half-dozen or so parts to try to solve this issue, since the car is 21 years old, but I don’t have the time or inclination to work on it now.
Taking it in to a local shop (that is reasonable and honest) tomorrow, will report back...
 

·
Registered 2002 SLK320
Joined
·
1,763 Posts
Hi,

Assuming it is running OK, the first thing I would do is to clear the Codes, drive it some, and see if they come back, .................

Dave's tip of the month ............

"Do Not Replace Parts Based Upon Fault Codes Alone" ;)

HTH
 

·
Registered 1998 SLK230
Joined
·
34 Posts
Discussion Starter #7
Some good news (hopefully): At first my local mechanic suspected the supercharger clutch, but fuse still blew when disconnected, and finally traced the issue to the forward O2 sensor or cable. He ordered the parts, and we’ll see what happens when replaced. Driving it as is until then...
 

·
Registered 1998 SLK230
Joined
·
34 Posts
Discussion Starter #9
Another thing I noticed is that the small squirrel-cage fan in the compartment that houses the K40, etc is not running. Should be always on, right? Couldn’t be on the same fuse?
 

·
Premium Member 2002 SLK320
Joined
·
615 Posts
It doesn't sound like it - see here:

Yes, it should always be on.
 

·
Registered 2002 SLK320
Joined
·
1,763 Posts
Another thing I noticed is that the small squirrel-cage fan in the compartment that houses the K40, etc is not running. Should be always on, right? Couldn’t be on the same fuse?
There is another current thread on here that had an issue with a fuse keep popping and it was caused by the ECU Box Cooling Fan it had also damaged PCB Tracks on one of the modules, (might have been N10/3 Module IIRC) .............

Without looking it all up and reading it again I recall he may have mentioned that Lambda was also on that fuse ????

Have a look on this Forum for that thread, it will likely still be on the first page ;)

HTH,
 

·
Registered 2002 SLK320
Joined
·
1,763 Posts
EDIT !!

You're lucky, I'm V Busy right now, but I just saw it .............

Read it all, conclusion is at the end, see if some or all matches your symptoms etc

Here is the thread to which I am referring :-


HTH
 

·
Registered 1998 SLK230
Joined
·
34 Posts
Discussion Starter #13
There is another current thread on here that had an issue with a fuse keep popping and it was caused by the ECU Box Cooling Fan it had also damaged PCB Tracks on one of the modules, (might have been N10/3 Module IIRC) .............

Without looking it all up and reading it again I recall he may have mentioned that Lambda was also on that fuse ????

Have a look on this Forum for that thread, it will likely still be on the first page ;)

HTH,
I would try that (unplugging the fan) but I can’t get the connector unplugged from the module.
 

·
Registered 1998 SLK230
Joined
·
34 Posts
Discussion Starter #14
Well, I don’t know how the mechanic tested the supercharger clutch, but over the weekend I unplugged it, replaced the fuse, and the fuse HAS NOT blown after a few test drives (and the radiator fan now runs when operating a/c).
Conclusion: short in supercharger clutch? Are these still available as replacement parts?
 

·
Registered 2002 SLK320
Joined
·
1,763 Posts
Well, I don’t know how the mechanic tested the supercharger clutch, but over the weekend I unplugged it, replaced the fuse, and the fuse HAS NOT blown
Buddy, I see this all day long, I wouldn't trust any of our local Garages / Mechanics to fix a kids Pedal Car let alone a Mercedes ;)
Sad to say that but it's true, and not just in the Motor Trade either, I certainly find that an awful lot of stuff I buy either doesn't work properly or goes wrong, not Chinese stuff either, so called Specialists eh :( :( :(

Sadly I don't have an S/C Clutch, but if I come across one I'll link you in ;)
 

·
Registered 1998 SLK230
Joined
·
34 Posts
Discussion Starter #17
Right, needless to say that I’m very disappointed in the two shops that have looked into this issue:

So I took a closer look at the cable going into the supercharger clutch, and it’s covering is off for about an inch, and the two wires are BARE COPPER for about half an inch where they enter the clutch!!! Gave the cable a bit more slack, made sure the bare wires weren’t touching anything, and lo and behold, fuse doesn’t blow!

Supercharger still doesn’t seem to be engaging, can see the clutch trying to turn when revving the engine, but at least I think I’ve solved the fuse problem...
 

·
Registered 2002 SLK320
Joined
·
1,763 Posts
I’m very disappointed in the two shops that have looked into this issue
Buddy that is why guys like yourself end up DIY'ing your Cars, and why I am way too busy ;)

Sadly the UK and other territories Motor Trade has very few decent Technicians any more, those that are any good are in demand, usually booked up at least 2 weeks in advance and can command decent hourly rates.

Doing it yourself you will get a much better job done, and with some help from guys on this Forum you can maintain your Car to a much better standard ;)

I am so glad you have found the problem, I hope the short hasn't damaged the ECU Driver or Clutch itself, someone who has better experience on the 4 Cyl Cars can hopefully advise you better, it may just be a case of the Clutch hasn't worked in a while so needs a good run to get warm and start working again, i have seen that on AC Compressors that haven't run for a while and they use a similar Clutched Pulley arrangement ;)

Maybe @jbanks15 @Avel Du and @LeonardoDaBenz can recommend a few members who are more knowledgeable on the 4 Cyl Cars than me ;)

HTH,
 

·
Super Moderator CA 2012 SLK55 AMG w/P30
Joined
·
11,976 Posts
1 - 20 of 50 Posts
Top