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Ask Lou P. master tech Your Own Question
Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3721
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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The drivers seat functions aren't working, it's a 2010 c300

Customer Question

The drivers seat functions aren't working
JA: What is the model/year of your Mercedes?
Customer: it's a 2010 c300 sport
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I am - I've checked the connections and then moved to the fuse box but it's not labeled - can you tell me which fuse to look for?
JA: Have you checked the manual yet? Most vehicles have two fuse panels.
Customer: I have - I'm looking at the one in the engine - figured it would be there
JA: Anything else you think the mechanic should know?
Customer: everything else on the door works but the seat buttons
Submitted: 3 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 3 months ago.

Hello my name is ***** ***** i will do my best to help you.I am looking over your info now and will reply back soon with some info , thanks!

Expert:  Lou P. master tech replied 3 months ago.

ok you want to check fuse 45 in the rear fuse box on the passenger side behind the panel. here is how the fuse box looks.

http://www.mediafire.com/view/cx0sqyq2mzw2bia/204%20rear%20sam%20fuse%20box.jpg

let me know if you find a blown fuse or not , i will check back in the morning. Lou P

Customer: replied 3 months ago.
Fuse 45 looks fine.
Expert:  Lou P. master tech replied 3 months ago.

ok so are all the seat functions not working or just a certain function?

Customer: replied 3 months ago.
The lumbar support button works. It's located on the side of the seat. All seat functions on the door aren't working including the memory settings. Everything else on the door works.
Expert:  Lou P. master tech replied 3 months ago.

ok. do you have a test light to make sure that fuse you pulled does have power?

there is a relay that powers that fuse , so if there is no power at that fuse the relay could be the issue., ill check the diagram again to get the relay location if you could verify power.

Expert:  Lou P. master tech replied 3 months ago.

here is the relay location

Customer: replied 3 months ago.
Thanks Lou, I'll be able to check that this evening once I return to the house. Not sure if I have a test light but I'll figure that out. Stay tuned.
Expert:  Lou P. master tech replied 3 months ago.

ok staying tuned :)

let me know, we can figure this out.

Customer: replied 3 months ago.
I used the tester I had for house plugs and got nothing. Not sure it even made contact though. I also switched out the fuse with another one and that didn't work.
Customer: replied 3 months ago.
Is that period of the door controls on its own relay?
Expert:  Lou P. master tech replied 3 months ago.

can you rephrase that last question please?

Customer: replied 3 months ago.
Sorry - is that portion of the door controls on its own relay?
Expert:  Lou P. master tech replied 3 months ago.

Ok yes. The relay will activate and allow power through the fuse to the switch assembly. Also your house tester is ac voltage correct ? We need to check for dc voltage. Either the relay is not energizing or the relay is bad.

Expert:  Lou P. master tech replied 3 months ago.

If there is another similar looking relay you can swap them and see if it then works.

Customer: replied 3 months ago.
Can you tell me what location the relay is located in?
Expert:  Lou P. master tech replied 3 months ago.
Yeah I sent you the picture of it a few messages back. Scroll through the chat and you will find it. If not let me know.
Customer: replied 3 months ago.
Gotcha ya. I passed over that one. Thanks.
Customer: replied 3 months ago.
I swapped the relay and that's not the issue. It must be in the door or under the seat. Just FYI - I'm also having issues with the driver door lock. It's not reacting regularly to the key remote or the door functions. And that was recent as well. All other locks work fine.
Expert:  Lou P. master tech replied 3 months ago.

ok let me go over the diagrams again and get you a process to narrow down the issue.

Customer: replied 3 months ago.
Sounds good. Thanks.
Expert:  Lou P. master tech replied 3 months ago.

sorry for the delay, i have been held up all day . would you want to do a phone chat this weekend like maybe sunday morning to get this taken care of?

Expert:  Lou P. master tech replied 3 months ago.

here is what we need to know,

in the rear fuse box use a test light and check to see if fuse 45 has power , if it does we need to check for power at the switch.

pins 1 and 11 are yellow with a black stripe, those should have power with the key on, if the fuse and wires do not have power then we need to check for signal at the relay. let me know if you have done stuff like this before and we can continue if needed.

Customer: replied 3 months ago.
I have not done anything like this before. Happy to give it a shot but will need to get a test light - correct?I was out of town but should be able to work through this in the next day or so.
Expert:  Lou P. master tech replied 3 months ago.

yes need a test light, not worried about multimeters or nothing, all we are going to have to do is confirm if the switch and fuse are getting power or not, then that will lead me to a determination of a failed switch or a failed power supply that we need to trace. it sounds harder then it is.

Customer: replied 3 months ago.
What am I looking for when purchasing a test light? Got a brand or model that is inexpensive but effective. There's an AutoZone near my house.
Expert:  Lou P. master tech replied 3 months ago.

a basic test light, they all work the same. no preference.

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