electrical issues - headlight and tail light flash with turn signals - ????

[joe czech]

finished up the wiring on my 74 yesterday. all individual circuits check out OK, but when I tie everything together, my headlight and tail light flash in sync with the turn signals. the only thing I can find in common with both circuits is the flasher - bad flasher? also, when I wire up the ignition or master switch, things seem a bit backwards. either I have an issue with the switch, or by some chance, is there an error on the factory wiring diagram? if I eliminate the switch, and jumper the connections, everything works, but I still have the headlight tail light flashing issue. I double checked every stinkin point to point wire connection including handle bar switch circuits, and I tested every individual circuit - individually, everything checks. I was thinking I might have an issue within the headlight pod, but again, checked individual wiring and everything checks. kind of a dead end. don't want to start throwing parts at the problem until I've exhausted all avenues.

back to the ignition switch, it bench tests OK with a DVM. installed, I wired it up to the factory wiring diagram - issues. when I initially tore things down, the master switch was wired accordingly. as I said, I can't trust anything done by previous owners -

upside down, and non-factory connections. the switch has two flats allowing mounting in two different positions. I would assume, the number one terminal is oriented at the top.

how about some comments from you electrical types. TIA....

 

[maylar]

There should be no unused tabs. If your headlight and tail light blink with the flashers, something is definitely wrong.

Lucas switch:

Wiring diagram -

https://granttiller.com/2019/07/04/norton-commando-wiring-diagram/

A white wire (battery) from terminal 2 feeds the flasher. The other end of the flasher is light green/brown and goes to the terminal block under the tank and from there to the blinker switch. The headlight should be fed by a blue/yellow off switch terminal 4.

 

[joe czech]

There should be no unused tabs. If your headlight and tail light blink with the flashers, something is definitely wrong.

Lucas switch:

Wiring diagram -

https://granttiller.com/2019/07/04/norton-commando-wiring-diagram/

A white wire (battery) from terminal 2 feeds the flasher. The other end of the flasher is light green/brown and goes to the terminal block under the tank and from there to the blinker switch. The headlight should be fed by a blue/brown off switch terminal 4.

according to your posted pic, that's how I had things wired. I jumpered wires 1, 2, 3,and 4 together, and everything works, but still have the flashing issue.

 

[maylar]

The headlight must be being fed from the flasher switch somehow. Something's amiss in the headlamp shell wiring.

 

[Steves]

Usually a ground/earth issue. Just repeating what I have read over the years, hopefully an electrical expert will chime in.

 

[joe czech]

The headlight must be being fed from the flasher switch somehow. Something's amiss in the headlamp shell wiring.

i'm going to double check it again. there is one ground wire I suspect as being wrong.

 

[maylar]

Normal wiring is from the flasher to the harness bullet bundle, to the handlebar cluster. Right and left outputs go into the headlamp shell to the blinkers. Headlight is fed from the ignition switch to the 2 way switch on the headlight shell then to the hi/low beam bat handle. If your headlight is flashing, something is not right.

Tail light, instrument lights and pilot lamp come off switch 3 brown/green.

 

[joe czech]

double checked the headlight wiring. I inadvertently connected a short ground wire from the headlight shell to the pilot, or parking light ground terminal. must have had some sort of ground loop or floating ground. things seem to be better, but now, no turn signals - they come on, but no flashing. there has to be an issue within the headlight pod.

 

[L.A.B.]

according to your posted pic, that's how I had things wired.

Not according to your drawing as you have:
Terminal 1 (brown/blue) which is correct.
Terminal 2 should be white, (not brown/green and blue/yellow).
Terminal 3 should be brown/green (not white)
Terminal 4 should be blue/yellow, (not unused).

The terminals also appear to be in the wrong order for the standard Lucas switch.

(The pic is one of mine)

 

[L.A.B.]

double checked the headlight wiring. I inadvertently connected a short ground wire from the headlight shell to the pilot, or parking light ground terminal.

There should be a 'ground' wire from the headlamp, pilot and shell connection to harness red inside the headlamp as harness red is the actual electrical system 'ground'.

 

[maylar]

(The pic is one of mine)

Google Images found it for me.

 

[L.A.B.]

Google Images found it for me.

Well, anyone is welcome to use it.

 

[joe czech]

Not according to your drawing as you have:
Terminal 1 (brown/blue) which is correct.
Terminal 2 should be white, (not brown/green and blue/yellow).
Terminal 3 should be brown/green (not white)
Terminal 4 should be blue/yellow, (not unused).

The terminals also appear to be in the wrong order for the standard Lucas switch.

(The pic is one of mine)

agreed - the pic I posted is the wiring when I bought the bike. currently, it's as you posted. BTW, can't see your pic.

 

[L.A.B.]

currently, it's as you posted. BTW, can't see your pic.

I don't know why that is but that pic has been copied by someone else so try this:

 

[L.A.B.]

all individual circuits check out OK, but when I tie everything together, my headlight and tail light flash in sync with the turn signals.

Does removing the tail lamp bulb stop the headlamp flashing?

 

[rvich]

Is this bike wired postive ground? All of it wired that way?

It sounds to me like one circuit is somehow providing the ground for the other through the bulbs.

 

[joe czech]

I don't know why that is but that pic has been copied by someone else so try this:

that's my current configuration -

this is where i'm at currently. headlight work OK - high beam, low beam, pilot, etc. the turn signals work correctly. HOWEVER, when I have the headlights on, the turn signals do not flash - they do flash with the headlights in the off position. i'm puzzled....

 

[joe czech]

Does removing the tail lamp bulb stop the headlamp flashing?

i'll give it a try.

 

[joe czech]

Is this bike wired postive ground? All of it wired that way?

It sounds to me like one circuit is somehow providing the ground for the other through the bulbs.

positive ground. i'll try isolating components. most likely, it's something simple. one thing - when I started the rewire, I check and tested each individual circuit and component. individually, everything checks OK.

 

[kommando]

Suggest you also check the main connection point under the tank where the 5 double connector is, some misdirected wires here could give the symptoms you are describing.