Unimog Alternator Problems, also Wiring Diagram and Manual Needed - Mercedes-Benz Forum

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post #1 of 6 (permalink) Old 07-13-2012, 11:12 PM Thread Starter
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Unimog Alternator Problems, also Wiring Diagram and Manual Needed


One day when I start the engine of my Unimog, the RPM did not function. And then smoke comes out from the dash board. I see a brown wire, burnt from the dust on the alternator. I would like to rewire my Unimog, and I need a wiring diagram and probably the external voltage regulator too.

Any information on where to get an instruction manual and wiring diagram for the Unimog U1400L would be highly appreciated.

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post #2 of 6 (permalink) Old 07-14-2012, 06:42 AM
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Wiring diagram will be in here: Workshop Manual Set - U435 [UKD304022142] - $360.00 : Eurotruck Importers, Your source for Mercedes-Benz off-road vehicles and spare parts!

But that's for the 435, yours is a 427 so check with others to see if the wiring diagram is the same.

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post #3 of 6 (permalink) Old 07-15-2012, 05:40 AM
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the wiring is not different to other german vehicles, for searching use "anschuß lichtmaschine" and you'll find many diagrams.
i can't imagine the 427 having an external regulator, usualy integrated in the alternator.

for using instructions, usualy with wiring (i can ask if inclouded), look here:

www.BuchundBild.de Unimog-Shop - alles rund um den Unimog und MBtrac - Buch&Bild - Unimog Unimogs MBtrac MB-trac MB trac U 411 U 2010 U 404 U 406 Unimog 401 402 Unimog 403 406 413 416 Unimog 404 Unimog 407 Unimog 411 Unimog 417 Unimog 421 Unimog 424/

gut mog! justus.
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post #4 of 6 (permalink) Old 07-18-2012, 11:01 PM
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I just replaced my alternator on my Mog, the Brown wire that you have behind the instrument cluster is a ground wire, there should be a contact point where several wire are terminated. If it is loose or making a bad connection you can burn the wire or wires.
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post #5 of 6 (permalink) Old 07-19-2012, 03:19 PM
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Is this a common problem ?. I noticed on my Mog that the Brown wire is also just about "dust" and on my list for replacing. Seems a problem in the way MB configured the connection - or is there a common mistake owners make ?
Might be worth running an extra connection to the chassis/engine.
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post #6 of 6 (permalink) Old 07-19-2012, 06:18 PM
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That is what I am doing, there are about 6-8 wire that are brown colour and are terminated at one point. The heater hose that goes across the cab behind the instrument cluster has been rubbing on those wires and wearing the to the point where the copper is now bare. I am checking all the wires just to be on the safe side. That is a great Idea to run a dedicated line to the contact point, that way you are not relying on the cab braided wire from the frame to the cab for a connection. I will be running 1/0 welding cable from the negative side of the battery to the instrument side so that I have a great connection.
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