Mercedes s430 radiator fan stopped working. Replaced the fan motor and controller with a used unit from eBay. Still doesn't work. Has 12 volts and...

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Customer

Mercedes s430 radiator fan stopped working. Replaced the fan motor and controller with a used unit from eBay. Still doesn't work. Has 12 volts and ground at the connector. Has 12 volts at the small wire to the controller has a weak signal from the ecm at .38 volts and 7hz. The signal is the same weather the ac is on or off. The gauge works so the temp. Sensor is working. I have no communication with the Ecm so if a code has been set I can' clear it. All fuses are good. Check engine light is on.

Last updated
Ramy De Jesus
Auto Mechanic

Hello and welcome to ExpertHelp.com! My name is Ramy De Jesus and I'm going to do everything in my power to answer your question to your full satisfaction!

Before we get started, I want to remind you ExpertHelp.com is an independent professional support company. We are not associated with Mercedes nor are we paid to provide support on their behalf. However, we have helped hundreds of customers with similar questions and believe we can help you too. OK, let’s get started! :)

I’m available to chat now. Please let me know that you are ready by posting a response. I’ll leave my chat session open for the next 15 minutes or so and wait for your reply. If I don’t catch you this time, please respond with a few times (including your timezone) that work best for you and we can connect then.

Last updated
Customer

Hi, I'm online now

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Ramy De Jesus
Auto Mechanic

Hi Carl! Thank you for choosing ExpertHelp.com. Just to clarify, only check engine light showing on the dash?

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Customer

Still there ?

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Ramy De Jesus
Auto Mechanic

Before you change the fan did you check if the fan is working before you install it? Can you try to disconnect the positive connector on your batter for 5 minutes and connect it back again after 5 minutes and check what will be the result. I will be standing by.

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Customer

I'm wondering if my responses are going through ?

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Ramy De Jesus
Auto Mechanic

Hi Carl please refresh the page  for you to see my responses. Or scroll up or down to see the latest responses.

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Customer

Ok, I disconnected the battery and reconnected it. Check engine light is off now but the fan still doesn't come on. It's supposed to come on when the ac is turned on even if the engine is cold.

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Ramy De Jesus
Auto Mechanic

Thank you for your response. Have you tested the fan before you connect it to make sure it is working?

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Customer

No, I don't really have a way to test it. They use a brushless three phase variable speed motor. I did try to apply twelve volts to the OLD controller and I connected a pulse generator to it and nothing happened. It could be that the pulse generator that I used wouldn't go below 300 pulses per second, or it could be that the old controller was bad. I don't know which.

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Ramy De Jesus
Auto Mechanic

What year model is your s430.

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Customer

2004

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Ramy De Jesus
Auto Mechanic

Thank you for your response. Is the check engine light came back? Have you chedk the ECT ( Engine Coolant Temperature ) sensor. When this is actually faulty you will encounter check engine to show on your dash and also one causing the overheating as well.

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Ramy De Jesus
Auto Mechanic

If the ECT is good, there is a big possibility also that rhe old controller is bad.

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Customer

Check engine light is off now. Temperature gauge works so the temperature sensor must be working. The ecu uses the same sensor for both the gauge and fan, from what I've read.

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Ramy De Jesus
Auto Mechanic

If that is the case. Big possibility that the old controller is bad.

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Customer

That's what I thought too. That's why I bought a used one, unless the used one is bad too ?

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Ramy De Jesus
Auto Mechanic

Have the car run and monitor it. Turn on the AC and monitor if the temp will go up and then the fan is not working then there is a problem with the fan you bought or the controller as well. That is the bad think of purchasing a used parts. It is not guaranteed will work. But if you can return it and ask for replacement since it is not working.

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Customer

Ok, I can try that. I have to put the fan back in and fill the radiator with antifreeze again to do that. My concern is the low voltage signal from the computer. I checked on YouTube for answers too. One guy says he was getting a 3 volt signal from the computer. I checked the voltage right at the computer and it was the same as at the controller, so it looks like the wire harness is ok. Do you know if that voltage is within range or do you think the ecu is bad ?

Posted
Ramy De Jesus
Auto Mechanic

For the test that you will do from there we will determine that the ECU is bad since all the parts needs to be check and replace are already done. The voltage is actually within range. If the steps I will provide you will not work then possibility that there is a n issue with the ECU.

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Customer

Ok

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Ramy De Jesus
Auto Mechanic

I will be standing by for your updates.

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Customer

Ok

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Customer

Ok, are you going to send me a test procedure to follow to determine if the computer is good or bad ?

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Ramy De Jesus
Auto Mechanic

If the ECU is bad you will get a engine ligh error code. Have it running for about 15 minutes and if the engine light came back then possibility of a bad ECU. Or if you have a OBD2 scanner have it scan for you to get the correct error code.

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Customer

Ok, I'll try that, but my scanner won't communicate with the ecu. But I can fill it with antifreeze and let it run for about 15 minutes without the fan before it overheats.

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Ramy De Jesus
Auto Mechanic

I see. I will standby for your next update.

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Customer

Ok, I was just outside for a while. Thanks for all your help. If I have any further questions I'll contact you. For now I can't think of anything else. Carl

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Ramy De Jesus
Auto Mechanic

Please do not forget to click on the Green Accept Answer button for me to receive a credit for assisting you. Thank you for allowing us to help you.

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Ramy De Jesus
Auto Mechanic

Dear Carl, It was a pleasure helping you with your Mercedes issue today. Here is a summary of the resolution.

Issue identified : Radiator not working
Solution Implemented : Live chat. Assist customer. Provide steps and possible solution to resolve the issue on this page. Customer appreciate our assistance. Customer accepted. Chat ended.
If issue resurfaces : Advised to contact us at s**t@experthelp.com or call us on our support number ***-***-**** )

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