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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4805
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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C300 Drs light on horn won't work air conditioning won't

Customer Question

C300 Drs light on horn won't work air conditioning won't work headlights won't turn of when locking car turn signals won't work
All thi happened at the same time
Submitted: 1 year ago.
Category: Mercedes
Customer: replied 1 year ago.
Turn signals, horn, air conditioning, won't work also SRS light on, STS light on, head lights when on Auto won't turn off when I lock the car. Checked fuses ok
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Lou P. master tech replied 1 year ago.

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

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

ok can you clear a few things for me,

  • Drs??
  • STS??

those are lights that i am not familiar with in the instrument cluster. can you clarify those?

i even checked the owners manual for the warning lights on the dash and do not see those, i want to be on the same page.

Customer: replied 1 year ago.
Sorry ESP
Expert:  Lou P. master tech replied 1 year ago.

ok that is ok, as long as we are on the same page

so did it rain or was the car washed before this happened?

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

with that many issues it can be related to a fuse or the cutoff relay that will not power up, what we need to do , and please read this thoroughly,

is use a test light and with the car running , check every fuse for POWER, i am NOT looking for a blown fuse although one would be a bonus, we are looking to verify POWER at all the fuses and document those that do NOT have POWER so i can check the fuse diagrams and trace back to where the power is activated it.

Customer: replied 1 year ago.
Ok this will take sometime I will not be able to check until next week
Expert:  Lou P. master tech replied 1 year ago.

oh wow, ok, well, i hope the chat will still be open, you should be able to reply with no issues, so just let me know when you get the info and ill do what i can to help, Lou P.

Customer: replied 1 year ago.
Thanks... By the way I was thinking that it might be the SAM
Expert:  Lou P. master tech replied 1 year ago.

it could be, but the systems you have an issue with are systems that only have power when the key is on, so circuit 15 relay is what is activated via the ignition switch and the sam, so there are few things we need to check, you could be right, but i never assume the most expensive part. no matter what forums say :)