SLK32 ic pump relay question
Senior Member
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From: Middleboro, MA
Re: SLK32 ic pump relay question
Maybe that's why they used a 10 amp fuse for the SRT6.
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From: Gilroy, California
Re: SLK32 ic pump relay question
My SRT6 documentation shows F13 as a 5amp ... if that was changed to a 10amp ... well, that supports my theory : )
Chris
Chris
Senior Member
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From: Middleboro, MA
Re: SLK32 ic pump relay question
This is from the SRT6 service manual.
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From: Gilroy, California
Re: SLK32 ic pump relay question
this is from the SAME manual .... (different page) ... if you average the TWO values that Chrysler calls out .... voila ! you get 7.5 amps ... the Mercedes service bulletin value
It's great when we can all agree
Chris
Joined: Jun 2006
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Re: SLK32 ic pump relay question
here is the part of the schematic that shows the entire IC pump circuit. It is designated as "M44".
The relay that you seek is part of the "N65" Pulse Module. it is located in the same box as the fuse (drivers side on real cars ... passenger side on yours : )
However, I have NEVER ever heard of this (relay) being the failure. with rare exception, the pump fails (fuse blows) by 20,000 to 30,000 miles AND replacing the pump and fuse solves the problem.
Worth noting on my 1st SLK32 (which I bought at 30,000 miles) the pump was not running when I bought it. the fuse was blown and I replaced it (fuse only) ... and it worked (until 50,000 ?) when the fuse blew agian ... once more I replaced it (fuse only) and it lasted for more than 10,000 or 20,000 additional miles until it blew one more time (and this time the pump actually had failed) So. I finally replaced the pump for the FIRST time near 80,000 miles. NOW, on my 3rd SLK32, I bought it with 17,000 miles AND ITS FUSE WAS BLOWN ALSO when I bought it. I replaced the fuse and have put 1,000 miles on it since and it is still working fine. MY POINT... while this part does NOT last the life of the car, I Suspect it is slightly under-fused and often prematurely replaced. (I seem to recall a mention somewhere that a higher value fuse is used in other models, but never looked into it.
Hope the schematic helps,
Chris
The relay that you seek is part of the "N65" Pulse Module. it is located in the same box as the fuse (drivers side on real cars ... passenger side on yours : )
However, I have NEVER ever heard of this (relay) being the failure. with rare exception, the pump fails (fuse blows) by 20,000 to 30,000 miles AND replacing the pump and fuse solves the problem.
Worth noting on my 1st SLK32 (which I bought at 30,000 miles) the pump was not running when I bought it. the fuse was blown and I replaced it (fuse only) ... and it worked (until 50,000 ?) when the fuse blew agian ... once more I replaced it (fuse only) and it lasted for more than 10,000 or 20,000 additional miles until it blew one more time (and this time the pump actually had failed) So. I finally replaced the pump for the FIRST time near 80,000 miles. NOW, on my 3rd SLK32, I bought it with 17,000 miles AND ITS FUSE WAS BLOWN ALSO when I bought it. I replaced the fuse and have put 1,000 miles on it since and it is still working fine. MY POINT... while this part does NOT last the life of the car, I Suspect it is slightly under-fused and often prematurely replaced. (I seem to recall a mention somewhere that a higher value fuse is used in other models, but never looked into it.
Hope the schematic helps,
Chris
Forum Regular
Joined: Apr 2011
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From: Gilroy, California
Re: SLK32 ic pump relay question
Well, you can write it down, you have NOW heard of the relay going bad: https://www.crossfireforum.org/forum...tml#post912718
if you log the drive side of the relay (or replace the relay) you should have something more definitive
cheers,
Chris
Joined: Jun 2006
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Re: SLK32 ic pump relay question
Fair :-) Well, minimally, it was not the pump. For me, doing the jumper in the box on the driver's side did the trick. One can only deduce that it was the relay, as the computer seems to be reading temps correctly (based on Torque). If it wasn't the relay, it would have to be a glitch with the computer, which I find very implausible. Changing the relay though, is beyond what I want to do with this car :-)
Forum Regular
Joined: Apr 2011
Posts: 528
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From: Gilroy, California
Re: SLK32 ic pump relay question
Fair :-) Well, minimally, it was not the pump. For me, doing the jumper in the box on the driver's side did the trick. One can only deduce that it was the relay, as the computer seems to be reading temps correctly (based on Torque). If it wasn't the relay, it would have to be a glitch with the computer, which I find very implausible. Changing the relay though, is beyond what I want to do with this car :-)
While I've not heard of the charge cooler relay failing (yet), it seem it IS the most likely culprit in your case. HOWEVER, in order to know more conclusively, you would need to remove your " jumper in the box on the driver's side" and short the ECU drive signal (E5) to ground. If the pump runs (key must be in run position) your ECU (or the connection between the ecu and the N65) is the issue. If the pump does not, then the relay is the issue.
but it sounds like you have solved your issue to your satisfaction, so I understand if you don't go any further.
Cheers,
Chris
Joined: Jun 2006
Posts: 24
Likes: 0
Re: SLK32 ic pump relay question
Chris,
That is dead on. Sorry for being lazy and not citing the N65 diagram and post. My brain is so overloaded with work stuff that I didn't have the energy to reply with detail. That bit about testing E5 is really, really interesting. I may do this, just because the engineer side of my brain hates not knowing. I have the car stored for the winter, but will dig it back out in the spring and test.
I would like to help others who might be in the same situation. Is the relay replaceable? I would prefer to fix this right, then have the jumper between E2 and E7...
Best Regards
Scott M
That is dead on. Sorry for being lazy and not citing the N65 diagram and post. My brain is so overloaded with work stuff that I didn't have the energy to reply with detail. That bit about testing E5 is really, really interesting. I may do this, just because the engineer side of my brain hates not knowing. I have the car stored for the winter, but will dig it back out in the spring and test.
I would like to help others who might be in the same situation. Is the relay replaceable? I would prefer to fix this right, then have the jumper between E2 and E7...
Best Regards
Scott M
Forum Regular
Joined: Apr 2011
Posts: 528
Likes: 32
From: Gilroy, California
Re: SLK32 ic pump relay question
Chris,
That is dead on. Sorry for being lazy and not citing the N65 diagram and post. My brain is so overloaded with work stuff that I didn't have the energy to reply with detail. That bit about testing E5 is really, really interesting. I may do this, just because the engineer side of my brain hates not knowing. I have the car stored for the winter, but will dig it back out in the spring and test.
I would like to help others who might be in the same situation. Is the relay replaceable? I would prefer to fix this right, then have the jumper between E2 and E7...
Best Regards
Scott M
That is dead on. Sorry for being lazy and not citing the N65 diagram and post. My brain is so overloaded with work stuff that I didn't have the energy to reply with detail. That bit about testing E5 is really, really interesting. I may do this, just because the engineer side of my brain hates not knowing. I have the car stored for the winter, but will dig it back out in the spring and test.
I would like to help others who might be in the same situation. Is the relay replaceable? I would prefer to fix this right, then have the jumper between E2 and E7...
Best Regards
Scott M
your current set-up is actually considered to be an upgrade to many (having pump always come on with key in run).
relative to repairing or replacing the relay in the N65 ... FIRST, I would confirm that it IS the problem.
I could not find a pic of an r170 N65, but I suspect it is fairly similar to this w210 N65
if you had the N65 in your hand, I would look for cold (poor) solder connections both at the connectors and at the relay. I burnt relay contact could be cleaned as well.
Alternatively, you could wire in a "bosch style" 30/40 amp relay (externally)
connect E2 to 86 and 30 (or, if want to be "perfect" , wire E2 to 86 AND A1 to 30 ... but it will work the same)
connect E5 to 85
connect E7 to 87
hope that helps,
Chris
Last edited by latemodel21; Feb 26, 2019 at 01:40 PM.
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