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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: 3740
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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This is ***** *****, Trying to hook up my trailer and noticed

Customer Question

This is ***** *****, Trying to hook up my trailer and noticed fuse 70 is missing for the trailer
JA: Thanks. Can you give me any more details about your issue?
Customer: 2008 gl 320
JA: OK got it. Last thing — Mercedes Mechanics generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 7 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 7 months ago.
Hello, how can i assist you ? if you noticed the fuse was missing, did you insert a fuse?
Customer: replied 7 months ago.
I cannot insert a fuse because the fuse holder is also not there
Customer: replied 7 months ago.
The number 71 and 72 have the holder, with a fuse.
I hooked up the trailer but none of the lights were working, than I looked in the fuse box and noticed that there is no fuse
Expert:  Lou P. master tech replied 7 months ago.
ok that helps , obviously you have the trailer hitch and everything else correct?
Expert:  Lou P. master tech replied 7 months ago.
may i have your vin?
Customer: replied 7 months ago.
Hitch and everything is correct
Vin 4jgbf22e08a356042
Expert:  Lou P. master tech replied 7 months ago.
ok thanks, ***** ***** to ask, yes that holder should be there, i wonder if they put it in 72 on accident. 72 is for the trailer as well but in my diagram it goes nowhere. what color is the fuse holder for 72?
Customer: replied 7 months ago.
Holder is brown with a 20amp fuse
Expert:  Lou P. master tech replied 7 months ago.
ok thanks, ***** ***** it appears your model was either built with the trailer or it was added on, i wonder if that is what they did, let me check the work instructions. from what i remember we had to add the fuse holder.
Expert:  Lou P. master tech replied 7 months ago.
ok do you see the colors on the fuse box itself where the fuses are missing from? 70 should be brown, 72 should be red. confirm that the open spot has a brown color marking on the fuse box.
Customer: replied 7 months ago.
70 is red and empty
71 is purple
72 is brown
Expert:  Lou P. master tech replied 7 months ago.
all of the colors should go in order starting at the positive post66 green67 blue68 black69 white70 brown 71 purple72 red
Expert:  Lou P. master tech replied 7 months ago.
http://www.mediafire.com/view/ogaoe4tegi5nzi3/164%20f4%20trunk%20fuse%20box%20as%20of%2009-06.jpg
Customer: replied 7 months ago.
Ok, I had the order wrong
Than 72 is missing
Expert:  Lou P. master tech replied 7 months ago.
ok, so now that we know the fuse is ok, lol, let me ask what kind of lights are on your trailer?led lights will not work with mercedes unless you buy a special adapter from uhaul that will add resistance to the circuit.
Customer: replied 7 months ago.
Silly me!
Is it a problem that 72 is missing
Lights are regular. 1973 airstream
Expert:  Lou P. master tech replied 7 months ago.
no, like i said 72 is showing it goes nowhere in my diagram. may be used for additional accessories if needed i think. so what is the issue with the trailer hookup?
Customer: replied 7 months ago.
Ok
No lights,
No electric jackI had it hooked up to a 2014 ram pick up before. And it worked fine.
Is the order on the plug different?
Than I have to redo those
Customer: replied 7 months ago.
You have the schedule of the receiver for me? Which one is what.
Customer: replied 7 months ago.
No, I have no schedule for the trailer side.
But if you have it for the vehicle side, I can change the trailer side accordingly
Customer: replied 7 months ago.
Thnx Lou
Expert:  Lou P. master tech replied 7 months ago.
Sorry for earlier I lost track of time and I had tickets to the monster jam monster trucks for me and my 2 year old. So sorry that is not like me. Did you still want the pinouts? Keep in mind that Mercedes trailer wiring is very basic and is only for lights. And it's control module controlled so if there is not the right amount of resistance with the trailer it will not allow the lights to be activated. Let me know if you still need my help. Again my deepest apologies.
Customer: replied 7 months ago.
The pinouts would be helpful.
I am going to use a prodigy rf brake controller. It works of the brake lights and is remote controlled. So no need for a fixed brake controller.
But yes I do need my lights to work for that.Btw hope you had fun with your son!
Expert:  Lou P. master tech replied 7 months ago.
it was a blast man thanks for understanding, he is only 2 but he was fixated with the real life gravedigger lol. ok i will get you the pinouts, give me a few.
Expert:  Lou P. master tech replied 7 months ago.
on your drivers door there is a sticker with the vin, i need to know the build date it will look like this, 11/08,
Expert:  Lou P. master tech replied 7 months ago.
Here is the trailer pin out. hope this helps. Mercedes did not make a user friendly trailer hitch setup. so you are not alone in the frustrations of having a super nice expensive vehicle but have to mess around with a silly thing like a trailer hitch wiring. Please take a second and click the STARS above and rate my service 4 or 5 stars if you feel I have been helpful and please request me in the future. 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.Thanks for choosing just answer. Lou. also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED !