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  #1  
Old 05-25-2018, 08:26 PM
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76 280c aux fan fuse box in left fender underhood wiring

aux fan fuse box .mounted in eng compartment . behind main fuse box . question is I have a red wire from fmain fuse box hot all the time . and a blue wire .and a black one. in Mercedes wiring diagram from batt bus to one end of fuse box f20 . theres a bk /rd wire . tthen on other end of fuse box .theres a red and blu wire going to aux fan relay . this f20 box has 2 separate fuses and I only have 3 wires . and trhe wires are black . blue and this red coming fr fuse boxmain ? cant find the main fusebox in Mercedes electrical troubleshooting manual .trying to post diagrams and pictures
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Old 05-26-2018, 10:24 AM
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Originally Posted by huffandpuff View Post
aux fan fuse box .mounted in eng compartment . behind main fuse box . question is I have a red wire from fmain fuse box hot all the time . and a blue wire .and a black one. in Mercedes wiring diagram from batt bus to one end of fuse box f20 . theres a bk /rd wire . tthen on other end of fuse box .theres a red and blu wire going to aux fan relay . this f20 box has 2 separate fuses and I only have 3 wires . and trhe wires are black . blue and this red coming fr fuse boxmain ? cant find the main fusebox in Mercedes electrical troubleshooting manual .trying to post diagrams and pictures
When rain stops, I'll go see id I can take a pic or follow wire.
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1976 280C
SLOWER DRIVERS KEEP TO THE RIGHT.
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Old 05-26-2018, 12:55 PM
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thomas

thank you !! I HAVE MERCEDES ELECTRICAL TROUBLESHOOTING MANUAL 75 =1979 MODELS . ONLY THING THIS DOESNT COVER IS THAT MAIN FUSEBOX. YES PICYURES DO SPEAK A THOSAND WORDS . 76 280C 114073 CHASSIS .
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Old 05-26-2018, 08:29 PM
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Originally Posted by huffandpuff View Post
thank you !! I HAVE MERCEDES ELECTRICAL TROUBLESHOOTING MANUAL 75 =1979 MODELS . ONLY THING THIS DOESNT COVER IS THAT MAIN FUSEBOX. YES PICYURES DO SPEAK A THOSAND WORDS . 76 280C 114073 CHASSIS .
Well, I guess it'll be a few days. Alberto is messing around in the gulf and we're scheduled rain for the next five days.
Tomorrow if I catch a dry spot I'll go out and shoooot some pics.
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1976 280C
SLOWER DRIVERS KEEP TO THE RIGHT.
DRIVE RIGHT PASS LEFT
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  #5  
Old 05-27-2018, 11:31 AM
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76 280c 114073 chassis f20 aux fan fuse w iring

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Originally Posted by Tomas7 View Post
Well, I guess it'll be a few days. Alberto is messing around in the gulf and we're scheduled rain for the next five days.
Tomorrow if I catch a dry spot I'll go out and shoooot some pics.
thank you be safe global warming is real remember reading an article about the animals trying to move up north fr Miami
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  #6  
Old 05-28-2018, 12:18 AM
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Look for a fuse box on the passenger side, on the inner fender. It should be one of those small ones that hold two fuses.

See that you have power in and out of it. Also, is there a relay in this circuit? This would be one of those small metal boxes with wires coming from the bottom. These will go bad but they are easy to test and even easier to replace. They are very expensive new but they do show up on evil bay now and then. You can also swap one relay for another to test the windows.

You can have someone hit the switch to move the window while you have your finger on the outside of a relay. If the system uses one you will feel it click if it is working.

And don't overlook a cracked wire where the door closes. This wire bunch sees a lot of flex over the years and will crack internally. And as weird as this sounds it is possible for both sides to break at the same time. What happens is the window you use quits due to a broken wire and then you find the other window's wiring busted long ago. You just didn't know it because you never use that window.

By the way, on your motors there is no positive or negative. The switch reverses the polarity for up and down, so both wires are negative and both are positive, depending on the position of the window switch. It only takes one wire to break to shut down the whole system.
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  #7  
Old 05-28-2018, 12:54 PM
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Quote:
Originally Posted by Idle View Post
Look for a fuse box on the passenger side, on the inner fender. It should be one of those small ones that hold two fuses.

See that you have power in and out of it. Also, is there a relay in this circuit? This would be one of those small metal boxes with wires coming from the bottom. These will go bad but they are easy to test and even easier to replace. They are very expensive new but they do show up on evil bay now and then. You can also swap one relay for another to test the windows.

You can have someone hit the switch to move the window while you have your finger on the outside of a relay. If the system uses one you will feel it click if it is working.

And don't overlook a cracked wire where the door closes. This wire bunch sees a lot of flex over the years and will crack internally. And as weird as this sounds it is possible for both sides to break at the same time. What happens is the window you use quits due to a broken wire and then you find the other window's wiring busted long ago. You just didn't know it because you never use that window.

By the way, on your motors there is no positive or negative. The switch reverses the polarity for up and down, so both wires are negative and both are positive, depending on the position of the window switch. It only takes one wire to break to shut down the whole system.
thank you idle . I will check everything tomorrow. then post the soultution for future refrences thanks again
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