O-Option

Any ideas on why a supercharger would be "working" but putting boost out relief valve? Check engine light came on. Seems error codes point to supercharger. Dealer says thinks it may be either a clutch burned up or electronic control module burned up. One independent garage shows clutch working and electronics show good, however, agree that boost is escaping and not being used. Second independent garage agrees superchrgr working and boost is escaping but not found cause yet.

Any luck on "used" superchargers? pro or con?

aceangel

If it's a 2000 or less model and you're getting similar codes to this: P1420, P1525,P1235,P1236 you have a problem with your k40 relay.

Open up your computer box, and look for the K40 relay. It's a small box next to the STAR Mercedes Benz connector with "40" relays on it. Replace it or open up and resolder bad points.

O-Option

Do you think this could still be the problem? Thanks

aceangel

Yes, 2000 - 1998 have the K40 relay module.

O-Option

The third diagnosis is that the clutch on the supercharger burned out which in turn damaged the part of the Electronic Control Module that controls the supercharger. Clutch part = $390 $200 labor to do clutch replacement.

*** The ECM is warrantied to 80,000 miles with no year limitation. this 1998 has 56,000 miles. So the ECM will be replace under warranty.
after three shops reviewing, i am going with this fix. Hope and pray it is correct.

ps:
Benz dealership said clutch and supercharger only came as a unit, could not break apart ** not true
Benz dealership never mentioned ECM was under warranty even tho it was a damaged part they disclosed

aceangel

I hope that'll fix your problem! Always good to get a brand new part under warranty!

benzmodz

Every single part of the SC is sold by EATON.

bazzle

The supercharger bypass valve motor (associated electronics) have been known to fail and stay open.

Bazzle

QuickSilver2

Hello.

I have 1420, 0446, 0443, 1525, 1235, 1236, 0135, 0141 after replacing my supercharger with a rebuilt one from eBay.

So where is the computer box?

budnball

just replaced a supercharger clutch after a week in the shop $850 at the dealership, tho they did give me a loaner for $15

john kvam

Got errors p1235 and p1236 on my 2000 SLK230. One tech wanted almost $3K to replace the supercharger clutch and bypass actuator. After rejecting this fix - and finding this forum, I went to a second tech. He found the broken wire on the connector to the Supercharger Bypass valve. Sure was a lot cheaper to fix the wire.
Thanks guys,
- john

C230 Sport Coup

I'm curious, since you guys have had the M111 engine for a long time,
what is the expected lifespan of the supercharger before it needs replacement?
I have a 2002 C Coupe, which has the M45 Eaton SC, same as you, but without the clutch.

So far so good, but at 124K miles, I'm considering pulling and having it rebuilt just for good luck, and reliability.

I'd rather do it in advance, for less money, then wait till it breaks on the side of the road, and leaves me stranded.

But I was reading some articles on the Eaton SC's, and there is this guy who works for Eaton as a tech rep. He stated he feels like the
Maytag repairman since in his words, "they just start to loosen up at 100K miles".
I don't have any reason to beleive it's going bad, other than, hey I'm at 124K miles, and 100K of that is with the ASP pulley.

I'd appreciate any input from people who've had their die (and I don't mean the clutch) and had to replace or rebuild.

As such, I'd like to know, what were the symptoms before it died?
Did it give any warning?
When it did die, how did you know?
Was it a catostophic event, or a slow death
with loss of power?
Or was it, one day it was making a horrible noise? (bad bearing?)
or did the seals give out and spew oil?

Enquiring minds need to know.

I'm going to pull the alt and drop it off locally, have new brushes put in,
but the SC, I can't find anyone local, and it would be at least a 1 week turnaround, and I only have one car.
(but there's a place in Oregon that does it for $300 and they replace the rear bearings as well, something most places don't)

bazzle

Me? I checked the SC oil at 160,000k and it was clean as. Leave alone unless it really bothers you.
You dont need to remove alt to change brushes, just remove neg batt lead, remove sump cover, undo wires on alt, undo 2 screws and pull brush pack out, replace if worn.

Bazzle

pmajet

Two questions: where is the ECM located so I can check the K40 relay, and 2) where is the bypass valve of the supercharger located so I can check if there's a broken wire.

Also, is it really true the ECM is warrantied to 80K?

Thanks

Marc99GT

Lots of bad information in this post but I digress.

The ECM better known as the ME is located next to the K40 under the cover where the 38 pin diagnostic connector is. MB parts are too expensive to just throw at the car. I have diagnosed these problems before and it was usually the clutch or the ME. If the clutch is constantly engaged, you can disconnect the 2 pin connector(looks like a little barrel with 2 wires clipped to the engine) and see if the clutch disengages. If this happens then you know the K40 is supplying power, the ECM is supplying ground(or wire is grounding before the ECM) and the clutch is not seized all in one shot. The K40 provides constant power and the ME grounds the circut at connector F Pin 21 on the ME. Usually you get a P0806 code if it is constantly engaged and the air flap stays open as a default so the system does not over boost.

The only real way to tell for sure is using the Star Diagnostics machine at the dealer and in actuations, activate the clutch on and off and the diverter motor or bypass. Usually if the ME is bad or stuck providing constant ground, it will not switch off and on (You can feel it and hear it with engine off). This is not a simple problem to solve, but some things can be eliminated quickly.

PS. Under the basic warranty, the ECM is not covered for 80K to the best of my knowledge. Only some emissions related parts.

Former Mercedes Benz Tech and MB ELITE Graduate

tjprice10

Sorry to bump this after such a long time..

But my 2000 SLK230 75k threw the standard codes that appear when the K40 is messed up.. So I just replaced it. But I am still getting a P1236 and my supercharger Bypass valve is still stuck open.. I checked if my K40 was supplying the supercharger clutch with power by disconnecting the switch and the supercharger kicked out. And when pluged back up it kicked in. But now the supercharger is always on, even at idle with the valve stuck open..
Cleaned the MAF
Checked fuel preassure
Checked Spark
All are good.
Just getting P1236

Any suggestion marc or bazzel?

cascooscuro

Hi there everybody from Spain.

Same problem here, like tjprice10.

Supercharger always on, bypass valve always on.
I have:
Checked K40 relay board. No burned connections.
Cleaned MAF and tried with other one
Checked for oil on ECU. No oil.

Just getting P1236.

I'm desperate...

Fredrik Nyström

Try to reset the bypassvalve.

1) Key in ignition in off mode. Close the bypassvalve manually and hold it in closed position in 5 seconds.

2) Turn on ignition for 15 seconds, you can hear and see the bypassvalve adjust itself, close etc.

3) Turn off ignition for 45 seconds.

Ready to go, hopefully with normal boost.

Otherwise, dissconnect the - battery for 15 minutes. Reconnect and start car. Let car idle for 5 minutes to readapt STFT and other values.

This hopefully works for you when you lost boost and no other parts are brooken.

/Fredrik

cascooscuro

Hi Fredrik. Thanks for your answer.
When you say Key in ignition in off mode, you mean car stopped or key turn fully left?
I ask you about this because you say to hold bypass valve closed for 5 seconds and if I turn the bypass valve to closed it remains closed if key is fully left...otherwise I cannot keep it closed (too strong).


The key has 3 positions (with 4 car states):
1- Fully left (like no key inserted)
2- Middle (only radio works for me)
3- Fully right (with engine stopped)
4- Fully right (with engine started)

Can you re-explain using this codification?

I'm a little bit lost...

Many thanks!

FLBRAT23

Sweep

Hi what is readapt STFT ??
I have the same problem