Topic: 1976 cb750K Front Running Lights?

[BenelliSEI]

Spent a few hours diagnosing an interesting problem on my 1976 cb750K6 today. Both front turn signals (the large “pancake” style) contain dual filament bulbs in the correct socket. Solid light blue and solid orange wires are the bright (+) feeds. The light blue with a white band, and orange with a blue band wires feed (+) to the lower intensity running lights. Both lamps are grounded internally and both stalks have a ground wire connected to the square washer under the fixing nut, inside the headlamp housing. Both turn signals work as they should.

The running lights are plugged into the corresponding, matching wires inside the headlamp housing and feed into the main harness. Note that on this model there is no light switch. The headlight and tail light come on with the key switch. The headlamp has the usual Hi-Lo switch on the left bar controls. Regardless of what I did, there is no power being fed to the front running lights.

So I pulled out my factory manual (cb750K6 Supplement) and traced the banded wires back from turnsignals. Sure enough, they plug into the main harness (just as I did). Follow those two feeds back through the harness and guess where they lead? NOWHERE. THEY JUST END. HOOKED UP TO NOTHING. WTF? Obviously plans or regulations changed? Complete mystery. Surely there is an explaination?

I made up a short jumper harness and connected both running lights to the low beam feed. They shut off when running the high beam. They are working now, for the first time in 47 years. Very strange…..

[rotortiller]

Why not tap into the power wire supplying the headlight hi/lo switch, that way they stay on all the time.

[BenelliSEI]

I just thought this way they are on for “day time running lights”. If I ever use the high beams at night (I try and avoid riding after dark) the extra load isn’t needed.

Having said that, good idea. The short little harness extension I made is a 1-3 plug in, so I can move it over anytime!

[BenelliSEI]

I stand corrected! Stu pointed out the lights go out when the turn signal is switched on. The fault is likely at my switch. Given the solution works, I may just leave it alone. My batting average is pretty low when I take the switches apart!

[M 750K6]

I hate taking the switches apart. Next time I'll do it with the switch inside a see through bag, to save getting on the floor searching for ball bearings, springs and bits of plastic...

[bryanj]

They do go to the LH switch but a lot of pattern switches(and different models) dont have that facility so if somebody swopped the LH switch unit that can be your problem

[BenelliSEI]

You guys have me thinking on this. I will go back and make sure something just isn’t plugged in incorrectly. This bike is so tidy I’ve never really investigated. Everything else has worked perfectly since day one.

[MauiK3]

Wiring can use up a lot of thinking and fiddling. Quality time not spent on cat videos!

[RAFster122s]

I hate taking the switches apart. Next time I'll do it with the switch inside a see through bag, to save getting on the floor searching for ball bearings, springs and bits of plastic...

Dry cleaners bags work well for this trick… even if you need to go to dry cleaner and offer to buy a couple bags from them it is worth it!

[RAFster122s]

Install a fused heavier gauge positive wire from your battery and install a relay small automobile relay in your head light bucket running your new power feed to the relay, then move your headlamp wiring to switch your relay so the high and low beams drive small large-postage-stamp auto relays that are less than 1/2 inch thick/deep then your power feed from fuse box then you tie in and put together a secondary modern fusebox or just waterproof fuse holders or put them accessible in side panel and tie them down so vibration is not causing the wires to fatigue or the vibration doesn’t cause your fuse holder to go intermittent after some corrosion and vibration related failure…

[RAFster122s]

Wiring can use up a lot of thinking and fiddling. Quality time not spent on cat videos!

Or FakeBook time wasting and sohc4 time investing…nah it is wasting time often…
Time the finite resources we squander constantly!

[HondaMan]

You guys have me thinking on this. I will go back and make sure something just isn’t plugged in incorrectly. This bike is so tidy I’ve never really investigated. Everything else has worked perfectly since day one.

These are the sort of 'strange things' I mention sometimes about the K6 bikes' wiring. They usually fixed this issue with short jumper wires that were not of their normal configuration, which was: one end would be a male plug and the other always a female, or both female, so shorts weren't possible if unplugged. In the K6 this became impossible because they had already switched to using the F0/1 (and a few F2) style wiring harness, and had the 'extra' wires that used to fit into the F0/1 triangular 'box' under the fuel tank simply made longer to reach the headlight bucket, running from the harness under the tank (near the coils) to the headlight in a separate black sheath. In so doing, though, the ends of those connectors were the wrong gender (both female) and wouldn't plug into each other, so the techs made short jumpers with male plugs on both ends. The wire color matched the major color of that circuit, with a band on one end of the jumper that was in the color of the stripe found on the major wire. Usually these jumpers came in Black with a White or a Yellow band, Blue with the White band and Orange with the White band, and sometimes Black with a Red band. These plugged together either the F0/1 harness with the K5-style headlight and handlebar controls, or else the (then brand new) F2 harness with the K5 handlebar controls and the different keyswitch wiring of the F2. I've even seen "wye" jumpers made with male ends on all 3 ends.

Trouble is: none of this was ever documented into their schematics. It became up to us to follow the colors for their function and figure out the puzzle their assembly techs were telling the mechanics!