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Discussion Starter · #1 ·
I've been working with this 81 for about a week now. I did break down and order a whole new (used) wiring harness to replace the old nest that PO left me. That went on with a breeze. Found the right plugs for just about everything. Wired up the OE blinkers up front and used the after market unit PO installed in the back. This is using an aftermarket headlight as well. I've got power to everything, the bike cranks (gas tank is off so no running), brake lights work, blinkers front and back work, high beam and low beam work, horn works, dash lights for indicators, oil, and neutral work but no running lights or gauge lights. I thought I swapped something on the rear on accident so I switched some wires and sure enough I get rear running lights when I hit the brakes. After I realized the front turn signals were 3-wire units I started investigating up there as I've got no front runners either.

What I found was a green wire cut from the red plug and a mysterious brown wire that looks like its on the harness side but coming from the ignition switch. I'm at a complete loss for this.

CM400 Cut Green Wire Front of bike.jpg CM400 Mystery Brown Wire.jpg CM400 Tail light wiring.jpg

Its worth mentioning that the main reason I got a new harness was due to the fact there were more wires missing than were there. When I bought it, it had a steady high beam, taillights with license plate light and brake lights. That's it. Other than that, it was only necessary wiring to make the thing run.
 

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Discussion Starter · #3 ·
Fixed my running lights. Turns out it was a blown fuse. Or at least that's what I'm blaming it on. I rerouted my wires into my headlight bucket and replaced the fuse at the same time and no its working. I still have the same mystery wires going nowhere but they all work. The fuse didn't look blown but I guess that's the fun with these glass fuses
 

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The 2 side lights in the rear are turn signals only, not running lights.
 

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By mystery wire you're referring to the extra Brown wire in the headlight bucket and an extra Green in the left side panel? If so that's correct. The Brown was there for a headlight park light required in some Euro countries and the Green is a an extra ground that is for a 3 wire flasher which some countries used.
There are 2 types of glass fuses. SAE which is found in auto parts stores and too long to fit the fuse block brass clips properly, they partially connect which causes overheating and melting of the fuse block. METRIC which are shorter, also found as AGC,
 

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Discussion Starter · #6 ·
LongdDistance, Thank you so much for solving those wires for me. And I must have lucked out on the fuses I picked up because they sit perfectly in there though I did buy them from the hardware store rather than an autoparts store strictly because it was closer lol
JT, I figured it was a two wire blink only system out back. My problem comes in where its actually an aftermarket rear lighting setup where the taillight (or Runner), brake light and signals are all in the same "bulb"/housing deal. I was just referring to the rear runners as tail and license plate light.

Some confusion also came in where I have an aftermarket headlight and no indicators. Luckily I did have the stock indicators on hand which were three wire units and helped me understand the front end wiring setup. Now I've got some 3 wire LED indicators on order and it should be set from there.
 

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With LED turn signals you will need an electronic flasher, the conventional one will not work at all.
 

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By mystery wire you're referring to the extra Brown wire in the headlight bucket and an extra Green in the left side panel? If so that's correct. The Brown was there for a headlight park light required in some Euro countries and the Green is a an extra ground that is for a 3 wire flasher which some countries used.
Got any clue what the extra ground connector under the seat is for, by the tool tray? There's a single male to double female connection.

I found it convenient for a wiring mod I did, but I presume it was there for some feature my motorcycle didn't have ('81 CM400E).
 

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Probably for the CB400T rear turn signals, that model had different turns that needed a ground wire. One harness made to fit all the different models.
 
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