peterwashere

Hello.

Have a 2005 C55 and the dreaded coolant workshop message has displayed.
What's going on:
-fan does not turn on when above temperature
-starting to reach upwards of 100c. I don't let it get any hotter as I shut car off if gets warm.
-fan does not turn on when a/c or front defrost is switched on.
-discounted the coolant sensor (by thermostat) as a test and the fan did not turn on.
-heater does work as well as a/c blows cold aso long as temperature doesn't get to high.
-turning on heater will keep Temps down but it does still like to climb.
-engine heats up as expected, somewhat fast maybe?

Where should I go now?

History:
Replaced radiator because it was leaking on drivers side bottom. Coolant changed and topped off etc. (Did this repair myself)
-during the radiator install one of the transmission lines did not set to well and popped out and transmission fluid line leaked at connection to radiator. FIXED by snapping it in correctly with clip etc. Did have to add some fluid as "enough!" Leaked.
-no leaks anymore from coolant or transmission.

I've read all over here that many are finding fan assembly to be okay but a loose wire or relay is issue.
Other say fan assembly replaced works..


Questions:
1) which fuses or better (locations) should I check. I looked at obvious #51 and it's ok. As for relays not sure which ones to ticker with and location of them?

2) Can I use alligator clips to connect to fan assembly and power to battery to see if works, or is that a bad idea?

3) Should I just replace the fan? If so I noticed to different fan models. 800 watt and 650 watt (around there can remember exactly #'s but I know there is 2 selections for the C55 when searching?

4) Could the connector bemail bad due to fluid leak and transmission fluid leak on the splash gaurd. I know the plug is in the corner so not sure if that would do it? I also had to use some water down there to clean up the mess?

Any ideas or suggestions would be greatly appreciated.

If anyone is in Los Angeles and has a Star or Scanner I would be very happy to meet you

ItalianJoe1

Probably the fan, they are a pretty common failure. If you get it tested with star it could confirm it though.

peterwashere

Thanks for the response Italianjoe1

I put a new fan (well as working used one) last night it still does not work. Really not that difficult to do by the way.

That being said I've read that a relay swap is a test (not sure which ones however). I also read that so.easy people had issues with bad wire in harness, not sure where to start there

As for a star i need to find an indy that has one I can use as I do not have one or a scanner. If anyone in Los Angeles knows a good place to go that would be awesome.

Thank you

NoSleep

I just spent quite a while dealing with this on my C32. I think the fans are the same - or at least their connections are. If your plug has 2 large contacts and two small contacts, I can tell you how to check it:

Checking the Car-side connector:

• The 2 large contacts should have battery voltage on them at all times.
• Check the two small contacts with your negative probe on chassis/Batt-.
  • One contact should have 12V when the ignition is ON
  • The second contact has a voltage proportional to desired speed. Your meter may read it as a pulsating signal or an average voltage between 1.2 and 12V.

If you replaced the fan and it didn't work, the problem may be on the vehicle side so hopefully this test will shed some light onto where to start.

Some background:
Originally I thought the Fan was CANbus after reading a few forum topics all over the internet, but turns out the fan itself is just controlled via a PWM signal. I was able to actually run the fan variable speed on the bench with the appropriate equipment to generate the PWM. The 12V that comes on with the ignition is basically an 'Enable' signal. OEM fans run full speed if you put 12V on this pin and don't provide a PWM signal. Aftermarket fans I've tested don't seem to have this fallback behavior though and always require PWM to run at all.

peterwashere

Thank you nosleep for the information. (love the username- considered it's now 3am by me...lol).

Seems these fans have caused lots of headaches for many. I'm going to bring it in somewhere today to have started hooked up on it. Hopefully they will be able to activate the fan via star like I've read.

Unfortunately, today I had to drive the car somewhere and got stuck in traffic on way back and had to crawl home. Drive a few blocks when traffic was good and pull over to rest the car. Of course this go around the coolant workshop message turned off and never came on. I say unfortunately because the car heated up to record levels for me. It pinned the 120 Mark once! Needless to say no more driving it. I was shocked that through message never came on nor the fan.

Doubt it but hopefully the coolant temperature sensor is the issue. Tried to trip (short) it to see if fan would kick on tonight using a paperclip but he holes are to small. Was thinking this as unplugging does trip it.

The temp gauge on car spiked a few times (flickered that is). That's what made me rethink the sensor. Then again over heating does wonders for cars!!

I have a Bluetooth obii sensor in car and was watching temperature reading on the tablet while driving. Not sure if accurate but the speed & rpm sensors report correct. Using Torque(pro) if anyone wonders. It doesn't read any codes from the ECU (I think it tries but doesn't work for benz). At least it doesn't read any on my car as I'm sure this issue would have thrown some fault codes for sure!

So people searching... had another issue after this heat up issue yesterday. The nav/radio decided to stay on and I couldn't turn it off using knob/ buttons nor could I switch the station etc. Only volume was working. I don't remember having the radio on either.... I found it this was when I went to the garage a couple hours later and noticed the radio was on!! Also the power windows no longer one click up nor does the sunroof. (Problems and more problems ahhhhhh!!!) Finally was able to turn the radio off by yanking the fuse under the hood #64 I believe it's a 15a fuse in the corner.

I love this car, everything about it. Just trying to get her back on the road... but healthy.

peterwashere

Bad girl, bad girl!!!!

insame1

ItalianJoe1 gave you the best advice so far. If you get this scanned they will be able to tell you what is wrong.

peterwashere

Bringing her in when the shop opens today. Hopefully a scan will find it.

Morphh

Could be thermostat?

peterwashere

Update:

Took it in they said it was the front SAM.
I hopefully this fixes it and it's not a lazy diagnosis.

But it does seem to make sense.
Anyone have some input?

Amir_AMG

any update? how much-did it fix the problem?

peterwashere

They needed to order a front SAM. About 750 parts/labor unfortunately the fan still didn't work.
They tried a tester fan and it did work, so a new one needed to be ordered and should be installed today.

Those fans are expensive (and the used one I picked was no good either) so unfortunately the bill is adding up. They tested the system with the tester so the front SAM was the issue (fan burnt out too.)

Updatea to come.