CL55_AMG_GUY

Hi everyone, I edited this so look below this paragraph for fan information. I have a 2003 CL55 AMG and can not get the fan on to save my life! I assumed it was just a bad fan and module so put out $500 for a new one and after installing I still have NOTHING! I have searched the forums only to find dead ends. Before replacing the fan I found that the 20A fuse was missing for it so I put in a new one and would get a VERY VERY short "Coolant Visit Workshop" every so often off and on and no fan. After removing the fan I got it all the time. With the new fan in place I haven't had it come on yet and the fan STILL isn't kicking on. I have read of hidden fuses in the range of 125-150AMP but I would imagine that more things in the car wouldn't work if one of them blew. Any help would be greatly appreciated.


What I have discovered in my voyage to resolve this issue.

Fuse 87 - 20AMP - Located on passenger side under the smaller box is associated to the fan
Fuse 30 - 20AMP - Located on passenger side in the primary fuse box is also associated to the fan
Fuse X4 - 100AMP - Located in the trunk behind the lining above the battery is ONLY for the cooling fan and if it pops the WHOLE box needs to be replaced

Fan should run when MAX AC is on - mine does not
Fan should turn on once 90C is reached - mine does not
Supplied 12v to fan speed wire and fan fires right up BUT I have a Coolant Visit Workshop!
Computer is requesting 40% power from the fan but the signal isn't getting to it.
Need to know where the yellow/blue stripe wire goes to so I can investigate further.

CL55_AMG_GUY

I checked to see if I was getting power at the plug and the results of the 4 post plug were as follows:

2 large wires, 12V and ground

2 small wires, 12V and 0.35v noting that the .35 is probably the signal wire and the 12v is power for the control module.

If anyone has any recommendations for me that would be great because I am out of ideas

CL55_AMG_GUY

Checked the hidden fuses under the passenger side foot well and everything was fine there. Did some more searching and discovered that the fans primary power wire has a 100AMP fuse in the trunk by the battery, checked it and all is in order... Maybe the replacement fan I received is defective but I find it strange that after installing it I no longer get ANY faults even if the car gets to 100C and higher with AC on MAX while it is 100 degrees here in Texas! Fan just doesn't want to turn on... I cross referenced the part number I received with Behr's site and it is the correct unit for the car... I hate to take it to someone but I just might have to.

shardul

iTrader: (1)

plug the fan connector and check for corrosion

CL55_AMG_GUY

No corrosion present at fan connection or anywhere else I have checked, thanks for the suggestion

shardul

iTrader: (1)

is the coolant level fine in the car? I know it is unrelated but on a 360 modena if the coolant level is low the radiator fans will not turn on.

CL55_AMG_GUY

Coolant level is perfect, I may have just received a defective fan I suppose. I am going to return it and order another one.

spratt22

Hi have you tried changing coulant temp sensor worth a shot for a few bucks

CL55_AMG_GUY

I might as well give it a shot and see if it helps! The gauge works properly though so if that does it I will be HAPPILY surprised!

CL55_AMG_GUY

Disconnected temp sensor, car strongly disliked it by running horrible. I read on another forum that the 4 prong fan (integrated control module) would go in to TURBO failsafe if it didn't detect a signal from the ECU so I unplugged the fan, removed the yellow with blue stripe wire as it tested at only 0.35v showing to be the signal and BOOM fan fired right up! So does that mean that the SAM module is bad? Wouldn't I have some sort of check engine light or warning signal? I feel like I am getting close to a solution. Some people in the CLK board said that often times neither the fan or the ECU was bad and in fact was the harness between? Any other suggestions would be GREAT!

Thinking maybe jumper to replace the wire BUT it is strange that it shows voltage so it leads me to believe that it is the ECU that it plugs into.

CL55_AMG_GUY

Ok, I bought the Launch EasyDiag tool ($37 shipped) and the Mercedes software ($40) so great buy! With the software I was able to find that the computer is requesting 40% power to the cooling fan which tells me the ECU is operating properly. Can anyone supply me with a wiring diagram from the M4/7 connector specifically for a 2003 CL55? I just need to know where the yellow/blue stripe wire goes to? This wire controls fan speed and is currently only putting out 0.35v so somewhere between the ECU and this wire it is losing the signal but I can't trace the wire without unwrapping everything which is something I don't want to do... Thank you in advance!

randall977

10 years on, I'm guessing no solution was found? I have this problem and it seems fairly common, but on no forum or YouTube (looking at other models with the same fan setup too) can I find any solution. My fault code reader can activate the fan at any speed, but with the engine on, nothing.

The choice seems to be an ECU fault, or my cheapo after market fan / controller (replaced by teh previous owner) not responding when the engine is running - perhaps due to a voltage drop compared to forcing it to work with just the ignition on?