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I need wiring diagrams for 2007 ML320 heated seats not working. Can anyone tell me where to get the wiring diagrams or service manual, or does anyone have a PDF i can use?? please help its cold here in canada! thanks
 

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W163 Crash Test Driver
2008 ML350 (Me!), 2010 GLK350 (Wife), 2003 ML-350 (Deceased)
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I need wiring diagrams for 2007 ML320 heated seats not working. Can anyone tell me where to get the wiring diagrams or service manual, or does anyone have a PDF i can use?? please help its cold here in canada! thanks
Please post your full VIN and I will look them up.
 

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W163 Crash Test Driver
2008 ML350 (Me!), 2010 GLK350 (Wife), 2003 ML-350 (Deceased)
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Thanks for jumping in 43sqd!

Here are the relevant docs. I also included your vehicles Datacard for future reference. You have a couple awesome and rare options! Heated Steering Wheel and Heated Screen Washer. Must be a Canadian thing! I started retrofitting those into my ML awhile ago and...well, life happened. I still plan on finishing, some day! ;)
 

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Thanks for jumping in 43sqd!

Here are the relevant docs. I also included your vehicles Datacard for future reference. You have a couple awesome and rare options! Heated Steering Wheel and Heated Screen Washer. Must be a Canadian thing! I started retrofitting those into my ML awhile ago and...well, life happened. I still plan on finishing, some day! ;)
That is some great info, thank you so much. I will have to look into this heated wiper thing I don't see any option for it!

So I checked all the other outputs from the SAM and they all seem to be working except the heated seats switches. I checked the back of the switch unit which also controls the hazard lights and off road options (which work) and there's two plugs on the back of it, although only one of them had wires going to it. It's a 10pin, right beside it is a 3 pin with notjing connected. I am curious if that is for the HS... Couldn't find anything in your drawings about it...
 

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W163 Crash Test Driver
2008 ML350 (Me!), 2010 GLK350 (Wife), 2003 ML-350 (Deceased)
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Oh, there are four schematics for the front SAM since it does so much. I just uploaded the one that contained the seat heater. Do you want the others?

Also you have the heated screen washer option. There is a small coil inside your washer fluid reservoir that hot coolant circulates through, heating the washer fluid up. That and your washer nozzles are heated. Some fancier Mercedes also have heated hoses, but I don’t believe 164’s did. Honestly it’s kind of a “fluff” option, as you don’t need it if you simply use winter fluid. But I think it’s cool!
 

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Well If there was a schematic that showed what color wires and size of connector that went into the back of the heated seat switches, if be able to test for power. Since there's two plugs on the back of the switch unit but only one being used.
 

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2008 ML350 (Me!), 2010 GLK350 (Wife), 2003 ML-350 (Deceased)
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Oh. The “upper control panel” as they call it. That’s where things go digital. That panel with your seat heater buttons talks to the SAM over the CAN buss. There are no wires that trace back to the seats or power going through those buttons. Think of it like your office printer. When you click print in Word, the request travels to the print server, which send it to the printer. Your office computer doesn’t talk directly to the printer. Just as your seat heater buttons don’t talk to your seats.

Clear as mud? 🤣 The whole car operates this way. When you push your window button, the button talks to the door module, which talks to the SAM module, which finally tells the motor to roll down the window. And just like an office where their may be 10 people printing things to 10 different printers, the CAN buss wires are also carrying data from dozens of data points. Sensors, switches, other modules, etc. All over a single pair of wires.

There is an unused connector on the back because you probably have unused buttons on the front. Blank button positions for options you don’t have, like Parktronic, etc.
 

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Hmmm okay. Well I still am not getting any signal to the buttons, when I bought the car it was parked for like a year, both batteries completely dead. Its got new ones now but I wonder if it's a programming thing... Why else would I get nothing on the heated seat buttons
 

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2008 ML350 (Me!), 2010 GLK350 (Wife), 2003 ML-350 (Deceased)
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If you follow the data flow, the buttons only light up if the SAM tells them to light up. And it only tells them to light up if the seats report back the proper current draw. If your seat heater elements are shorted or open, the SAM won’t tell the buttons to light up. The buttons themselves are probably fine. The next step would be to put an ohm meter on your seat heater elements and see if they are open or shorted. You should see similar resistance on all four heaters (two seats and two seat backs). If one is radically different, there’s your problem.
 

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It seems unlikely that both seats would have failed... Do you have a diagram that shows which wires under the seat are for the heaters? There must be an independant circuit for the heated seats from a fuse? (although i checked every fuse in 4 main locations in the car) i assume this yellow harness under the seat is for the heated seats because if i unplug it i still have all my power seat controls.
Harness.jpg
 

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@Planethill the way im reading the file "Switch heated seats on, off, over", the seats wouldnt be cancelled by the SAM unless there was a hardware defect in the SAM, temperature too high or an improper voltage... Unless im missing something
 

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Also just noticed the High Beams lights do not work in the "held" position, but they work if you pull the lever and flash them... im starting to suspect the front SAM unit might have some issues, or what may be worse is if some wired got chewed somewhere behind the dash or under floor... Is there a way to see codes without going to a dealer... I am getting the WIS program but im not sure if thats related...
 

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Do you have a diagram that shows which wires under the seat are for the heaters?
Here you go.

R13/1 is the driver seat, R13/2 is the driver backrest.
R13/3 is the passenger seat, R13/4 is the passenger backrest.
X55/3 is the "Left front seat contacting strip".
All the W15's are grounds to the body in the footwell.
Z204/4 and Z204/5 are listed as "Left/Right Footwell Voltage Distributor Connector (Circuit 31).

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I also attached the PDF and the Upper Control Panel PDF you asked about earlier.
 

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W163 Crash Test Driver
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Is there a way to see codes without going to a dealer...
For this problem? Only if you have an SDS computer.

I am getting the WIS program but im not sure if thats related...
No. WIS is basically the electronic service manual (Workshop Information System). It has all the procedures for repairs, wiring, etc.. All the documents I have posted for you are from WIS.

Since there's two plugs on the back of the switch unit but only one being used.
The unused plug is for the "Lower control panel" (#20 below). It is only present if you have the "Offroad Package" (SA 430).

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