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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4497
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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2002 clk 320 fan runs all the time have to pull the 60 amp

Customer Question

2002 clk 320 fan runs all the time have to pull the 60 amp fuse to get it to shut off
Submitted: 1 year ago.
Category: Mercedes
Expert:  Lou P. master tech replied 1 year ago.

Hello the fan runs for one of two reasons. 1- the ECM is shorted and it activates the fan as soon as the key is turned on. Or

2- the fan is shorted internally and the fan will run no matter the car is on or off. Which scenario do you have ?

Customer: replied 1 year ago.
Second one doesn't matter if the key is on or off
Expert:  Lou P. master tech replied 1 year ago.

Ok. Then the fan will have to be replaced. The ECM doesn't get power once the key is shut off so there will be no chance of it being the reason. You will have to replace the fan assembly. Hope this information helps

Customer: replied 1 year ago.
Thanks I'll try that
Expert:  Lou P. master tech replied 1 year ago.

Ok if you need further assistance I'll be here to help just request me :) Please take a second and click the box and rate my service GOOD OR EXCELLENT SERVICE if you feel I have been helpful and please request me in the future. If you feel I have not been helpful please DO NOT RATE BAD OR POOR AND WASTE YOUR MONEY , I will opt out to see if another expert can provide more or better assistance so you're not wasting your money!!. Thanks for choosing just answer. Lou. also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED ! 😉 Keep in mind then when you rate it does not end our conversation. you can still return here to me for follow up information if needed, Lou.

Customer: replied 1 year ago.
Hey Lou replaced the fan and I still have the same issue as soon as I put the fuse in the fan runs
Expert:  Lou P. master tech replied 1 year ago.

Ok , if that is the case then the ECM had failed and is commanding the fan to run.

Expert:  Lou P. master tech replied 1 year ago.

It is just really odd since the ECM is supposed to be off when the key is off. If you have a meter we can do some tests to confirm.

Customer: replied 1 year ago.
I do, but I'm not around the car right now. If you give me a few places to check I may have time Monday
Expert:  Lou P. master tech replied 1 year ago.

Ok I'm going over the diagrams now. I'll get you some things to try. Have a good weekend.

Expert:  Lou P. master tech replied 1 year ago.

Ok there may have been a misunderstanding. Did the fan have just have 2 wires on it ? There are 5 wires on the fan control module that is usually one piece with the fan assembly. Was your unit just a 2 wire fan ?

Expert:  Lou P. master tech replied 1 year ago.

There are 6 wires on the fan control module.

Pin 1 grey ( goes to fan )

Pin 2 brown (ground wire)

Pin3 red with yellow stripe (power from fuse 38 )

Pin 4 white (goes to fan )

Pin 5 green with blue stripe (signal from engine control module will have positive voltage when ECM is commanding fan on )

Pin 6 red wire white stripe (key on voltage from front Sam 12v with key on. )

So if there is voltage on the ECM signal wire then the ECM is commanding fan on , if there is not then the relay is shorted out. My apologies the relays are usually always part of the fan and that's why I suggested the fan in the first place. Let me know what you find.

Customer: replied 1 year ago.
I have a 2 wire fan looked for the fan relay is it the "A" relay in the fuse box in the engine compartment if it is I pulled all the relays there and the fan stayed on if it's somewhere else if you could send a diagram of its location it would help
Thanks
Customer: replied 1 year ago.
Or if you have the location of the fan module I have looked all over the Internet for a picture and haven't been able to find anything
Expert:  Lou P. master tech replied 1 year ago.

Absolutely I'll get you a picture. Again I apologize for the miscommunication

Expert:  Lou P. master tech replied 1 year ago.

I'll need your vin for the proper part number too

Expert:  Lou P. master tech replied 1 year ago.

Fan control module.

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