Blinkers Strangeness

Tornado · Oct 1, 2022

Coming home at dusk today, first time riding in dimming light on Commando in some long while, I noticed the opposite side turn signals flashing with the desired side. Much reduced brightness, but visible in reflect off shiny cars in front of me. Confirmed this happens front and back ends and on eithrr left or right selected turns. I'm running standard incandescent turns (my be even original bulbs?) And stock incandescent turn indicator lamp. Flasher unit is modern electronic type, I beleive an LED compatible type just b/c that's what I had in my spares box.
thinking maybe i've connect flasher terminals wrong way round or something so will try that first. Any other things to check?

Big_Jim59 · Oct 1, 2022

According to the wiring diagram the flasher indicator is wired to both the left and the right side of the unit. The indicator will flash with the correct side but the ground finds a path through the the flasher indicator to the opposite side. It is my believe that if the bulbs are not a high enough resistance then the current will light the bulbs on the opposite side all be it dimly. You can test this theory by opening the headlight and disconnecting the flasher indicator.

I just installed turn signals but have not hooked up the flasher indicator.

Tornado · Oct 1, 2022

Big_Jim59 said:
According to the wiring diagram the flasher indicator is wired to both the left and the right side of the unit. The indicator will flash with the correct side but the ground finds a path through the the flasher indicator to the opposite side. It is my believe that if the bulbs are not a high enough resistance then the current will light the bulbs on the opposite side all be it dimly. You can test this theory by opening the headlight and disconnecting the flasher indicator.

I just installed turn signals but have not hooked up the flasher indicator.

Yes that is how they are supposed to work, the incandescents are not supposed to get enough power to light threw the wrong side circuit. This is an issue with LED's for turn lamps as they light up with very little power, so leakage through indicator lamp is sufficient. They need a "tweaker" diode arrangement in the indicator lamp circuit to prevent. Incandescent should not need.

Bernhard · Oct 1, 2022

Bad, or poor earth on one side, I often see that in cars!

Tornado · Oct 1, 2022

Where does turn signal circuit ground to? Headlight shell or z-plate or??

L.A.B. · Oct 2, 2022

Tornado said:
Where does turn signal circuit ground to? Headlight shell or z-plate or??

The front signals should ground to headlamp harness red via the headlamp shell and sleeve connection (because the actual headlamp shell is not a good 'ground').

The rear signals (with the L917 tail lamp) do not have a local 'wire' ground, so the return is through the tail lamp/number plate bracket, mudguard/fender, frame and any further metal to metal joints to wherever a red 'ground' wire is attached, so head steady, rectifier stud, Zener ring terminal, etc.
However, an additional ground from the number plate/lamp bracket or individual signal can be connected to the harness/tail lamp red (using a double common connector, etc.).

Big_Jim59 · Oct 2, 2022

L.A.B. said:
The front signals should ground to headlamp harness red via the headlamp shell and sleeve connection (because the actual headlamp shell is not a good 'ground').

The rear signals (with the L917 tail lamp) do not have a local 'wire' ground, so the return is through the tail lamp/number plate bracket, mudguard/fender, frame and any further metal to metal joints to wherever a red 'ground' wire is attached, so head steady, rectifier stud, Zener ring terminal, etc.
However, an additional ground from the number plate/lamp bracket or individual signal can be connected to the harness/tail lamp red (using a double common connector, etc.).

I like to take a page from the Japanese play book and create grounds for everything. I am not a huge fan of attaching grounds to hardware in hopes for the best especially anything that has to do with the steering assembly.

Tornado · Oct 2, 2022

Since I recently replaced taillight bracket assembly with new repro unit, fully painted, I suspect the lamp stalks are no longer making a good connection to the mounting points. Will make some tests and scrape some paint where the large nuts contact.

L.A.B. · Oct 2, 2022

Tornado said:
Since I recently replaced taillight bracket assembly with new repro unit, fully painted, I suspect the lamp stalks are no longer making a good connection to the mounting points.

For the flashing side to use the non-flashing side as 'ground' then there must already be continuity between the two (presumably rear) stem mounts.
The poor connection, therefore, is more likely to be either the tail lamp bracket-to-mudguard or mudguard-to-frame/bracket (or both) bolted joints.

It should be easy to identify a poor ground connection by running a jumper wire from battery positive or a red wire connection point to the indicator stem or bulb housing.

Tornado · Oct 2, 2022

L.A.B. said:
For the flashing side to use the non-flashing side as 'ground' then there must already be continuity between the two (presumably rear) stem mounts.
The poor connection, therefore, is more likely to be either the tail lamp bracket-to-mudguard or mudguard-to-frame/bracket (or both) bolted joints.

It should be easy to identify a poor ground connection by running a jumper wire from battery positive or a red wire connection point to the indicator stem or bulb housing.

And to help eliminate variables, that new tail light bracket has failed at the lower/rear-most fixing bolt points, so no connectivity at that position.

L.A.B. · Oct 2, 2022

Tornado said:
And to help eliminate variables, that new tail light bracket has failed at the lower/rear-most fixing bolt points, so no connectivity at that position.

Yes, with broken lower tail light brackets not making good contact then the direction indicators would be relying on the painted support bracket for the ground connection.

Andover Norton - SUPPORT BRACKET (PAINTED) - 06.3727

SUPPORT BRACKET (PAINTED)

andover-norton.co.uk

Tornado · Oct 3, 2022

Measure 0.5-1 Ohm resistance from the z-plate grounding bolt to the rear turn signal stalks. The upper brace to the hoop was powder coated last winter and I suspect the fixing points need more scraping up to make good contact.

Went ahead and replaced the rear lamp/license bracket with another used one after giving it quick coat of gloss black paint. Had thought to arrange for proper blasting and powder coat, but wise to wait and see if this also fails in short order. I fit two rubber washers between lower mudguard to bracket fixing points.

Checked resistance to z-plate and now looking much better. Lamps not blinking without leakage to no selected side.

Danno · Oct 4, 2022

Happened to me during the Titanic restoration. Hit the button for right blinker and the left blinker came on and blinked. Turned out the hot wire for the right rear blinker was shorted inside the chromed tube stalk and was back-grounding to the other side.

Blinkers Strangeness

Tornado

Big_Jim59

Tornado

Bernhard

Tornado

L.A.B.

Moderator

Big_Jim59

Tornado

L.A.B.

Moderator

Tornado

L.A.B.

Moderator

Andover Norton - SUPPORT BRACKET (PAINTED) - 06.3727

Tornado

Danno

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