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Old 10-07-2015, 03:47 AM
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Join Date: Oct 2015
Posts: 3
85 300TDT lights / fuse / wiring problem

To keep this short I am leaving out part of my latest MB adventure.

I moved the right low beam / fog lights wiring, fuse #11 to fuse #5, and the right low beam and fog light are now working as they should. Except for the left low beam everything is working as it should.

Now I am trying to move fuse #13 to the empty spot at "d", but can't find the hot
wire for the left low beam. There are no stray wires. All I have is the yellow/black
wire that carries power to the left low beam.

I've checked the Haynes and Mercedes wiring diagrams even looked at the fuse box on another wagon but cannot "see" how power is delivered to fuse #13 for the left low beam. They just show "56b" splitting left and right.

I could try tapping into the hot wire to #11 (now #5), but wonder if anyone know
what I have missed?

Any comments will be appreciated.
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Old 10-07-2015, 09:57 AM
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Join Date: Jan 2003
Location: Matthews, NC
Posts: 1,356
Fuse 11 and 13 are connected together in the fuse block, probably. So fuse 13 normally gets its power from the same yellow wire that go to fuse 11. Just make a jumper wire from the power wire you moved to fuse 5 (yellow) and run it to the hot side of fuse D. Then hook the wire going to the left low headlight to the other side of fuse D. I can do electrical work in my sleep but have a very hard time describing what I am doing. If there are any questions about what I said above, please let me know and I will try to word it differently.

84 500 SEL (307,xxx miles)
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Old 10-09-2015, 01:38 AM
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Join Date: Oct 2015
Posts: 3
85 300TDT wiring fixed - (fingers crossed)

Thanks for your help. I just finished re-routing the wiring for fuses 11 and 13 to
no. 5 and "d"; added a jumper from #5 to "d", as you suggested, for power for the
left low beam. Replaced the fuses with the copper type. Checked to make sure every thing is working.

I'll be watching closely until I am sure that the problem started with a corroded fuse.
That diagnosis came from someone who tried to fix the initial problem - fuse
#11 started burning the box. His solution was to run a fused wire from the battery to
the other side of the slot. The lights worked fine for a short time then fuse #13 started to burn the box and the lights were doing strange things. I'm wondering if #13 was overheating because there was too much power going to the lights when the high beams were on or if it was feeding power that it did not need from 11 to 13.

If it is of interest to anyone, among the things I learned: If you have trouble working the
fuse box cover out, pull the end of the weather strip off the lip above it. Seems to help.
Also, right and left sides (a,b,c,d) of the box interlock with the main part and can be separated. Remove the two screws at the bottom. Push the sides down and to the back

Thanks again.
Richard M. ("Junius")

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