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Discussion Starter · #1 ·
Hello everyone, I have to access the turn signal flasher module. It's my understanding it is behind the panel sitting to the rear of the air cleaner panel. After removing the air cleaner panel there are two bolts that screw into this rearmost panel itself to hold it in place. However the nuts inside this panel are not welded and consequently I don't see a way to easily hold them in place in order to remove the bolts. Any help much appreciated. Steve
 

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Hi Steve,
Mine were welded into the panel
But if you're sure yours are not, split the halves of the side cover assembly using a 1/4 socket and screwdriver at the front, then unbolt air the filter housing from the frame and the rear cover will come with it
 

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Discussion Starter · #4 ·
Thanks much. I was just hoping to avoid unnecessary steps. Split the air box and it came apart relatively easily. Now to find the signal operating module.
 

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Discussion Starter · #6 · (Edited)
'Cept on this bike. Someone swapped a Denso module for the Lucas. Found it and the wires seem to match the wiring diagram. I'll hook up a known good Lucas unit (if there is such a thing!!!), wear my lucky socks and hope for the best!
 

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'Cept on this bike. Someone swapped a Denso module for the Lucas. Found it and the wires seem to match the wiring diagram. I'll hook up a known good Lucas unit (if there is such a thing!!!), wear my lucky socks and hope for the best!
I read here that there is a better Lucas and a worse one. Also, that you can use a universal car flasher unit from an auto parts store
But if you search "flasher" it'll probably pop up in recent discissions
 

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Discussion Starter · #9 · (Edited)
Well, I tried the Lucas one, right out of the box. Nothing. That is the issue. After installing the handle bar P clamps into the triple tree bushings and securing the nuts, the signals stopped. I went through all the connections in the headlight and wherever I could. All seemed OK. Possibly too much strain on switchgear and connections

:cry:
 

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first step is what you are doing -- visual inspection of all connections - after that its working with a wiring diagram to follow the "live" wire until you find the fault
 

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Of course, you may be changing the flasher unit when it is a good one and the fault may be in the switch. Search around. The 71 indicator arms have to earth through the various bits they are bolted too as they have just the one wire into the lamp.
 

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Discussion Starter · #12 ·
Thanks to all for your helpful comments. Yes, possibly a switch problem. I keep reminding myself no light works in the system in any way, steady or slow or..... I now realize the lamps earth via the clamping to the frame or rear mudguard or front headlight support. But the fact the total system is dead, has me puzzled. I'll refer to the wire diagram and start checking continuity.
I've had the switchgear off and opened several times to look for broken solder points and...but nothing. It seems fine. Not exactly looking forward to setting aside four or five hours with a DVM. My favorite type of afternoon!

Steve
 

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Hi Steve, The flasher has constant power to it with key on. Power goes through flasher to switch center pole.

Do this test. Hook the 2 flasher wires together. Turn on key. Center position of switch all lights should be off.
Move switch right turn. Right side turn bulbs & indicator should illuminate steady. (No flash as flasher is by passed).
Now do left turn left lights & indicator should light up constantly.
Back to center all lights should’ve off.

That test, test the entire system save the flasher. Until you pass this test with correct bulbs in all 5 sockets flasher will never work right.

New Lucas flashers are really bad internals built very differently from originals.

Oriellys auto parts & many others sells a small round 2 flat terminal flasher. About $6-8. It barely fits original holder, but will fit. Secure to holder with 2 zip ties so it can’t slide out.

Wrong flasher cannot cause damage to system. It will flash too fast or too slow, or constant on with lever flipped. But.., cannot damage bike.

with the flasher by passed any bulbs that don’t work must be corrected first. Bad bulbs, bad sockets, bad ground, bad wiring, bad switch.
Using a simple test light or bolt meter you can isolate most faults. This is very simple system once you understand exactly how it works.

Often can have multiple problems & bad flasher at the same time.

Once all problems are fully sorted & you get good flasher (not Lucas), the system is usually very trouble free.
Don
 

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Hi Steve, This original Lucas from my ‘73 Tiger.
17 72 on cover means made in 17th week of 1972.

A thermo relay. Tiny metal blade just above the copper rivet head gets hot from current flow to bulbs. Heat transferred to the nearly flat bimetallic spring causes it to flex suddenly. When hot enough spring flex’s with a pop & opens points. Lights go out.

It cools suddenly with points open & no current flow. Pops closed. Lights come back on.

So that’s the on/off cycle we call a flashing turn signal.

With switch in center position there is no current flow. So points default closed. Notice carefully after your blinkers are repaired, when you flip switch to turn, lights come on first, then begin to flash.

Again ignition switch sends power to relay whenever key is on. The power flows through relay to switch. But…. In real life it’s available power/current ready to flow. When you flip turn switch the current begins to flow through bulbs lighting them. At the same time the current flow heats the bimetallic spring. Pop the contact points open, lights go out until bimetallic cools.
Very reliable developed in the early 40s.

On my bike I commuted 35 miles a day in the rain. Flashing became temperamental with no lights coming on. Observation showed light didn’t come on right away flipping switch.
I bypassed flasher. Lights came on steady at flip of switch so I knew flasher was faulty. Local Triumph shop stocked flasher. A few dollars later I was good to go. Bike was in 2nd winter then. That new Lucas flasher is still working good to this day 30k miles later.

Years later I got curious & took it apart. Turns out somehow rain water had gotten inside cover. Same location as yours. It rusted bimetallic enough rust powder covered points & that was problem. Cleaned points it worked!

Old Lucas was pretty good really.
Don
 

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Here’s the modern pattern Lucas flasher.

Still bimetallic thermo flasher. Bimetallic spring is very different shape. No matter it still flex’s & pops over separating points.

However, see the white thread wound around a thin bar of metal? That is the heating element. Unlike the old style that had “bonded(“welded”) connections on heater, this one is crimped. Often poorly crimped, so it comes loose, goes open circuit & no heat, or crimp isn’t tight enough & looses current resulting in low heat & no or poor flash.

The new shape of bimetallic spring is such it’s much more prone to not popping over.
Mostly it’s the heater wire problems though.

It seems the heater wire is nichrome, which is very to solder successfully.

However….It’s possible that Lucas got the quality issues sorted. I hope so.
A few have had good luck with modern Lucas.
Both the failed Lucas flashers in my drawer are about 2 years old now. (These we’re on others bikes, not mine).

Finally gave up & got the Orielly’s flashers. They fit many (most??) American cars through 50s & 60s & some 70s until electronic flashers became popular. Electronic can turn on differently sometimes. You flip switch nothing, then flash. Taking them apart I see circuit board & relay. I don’t know how they work. Still won’t work with LED though. Now special LED flashers are made. I don’t know them either.

If I get chance tomorrow I’ll see if I can find the round relay from Orielly’s.
I’ll be able to get exact part #.
Don
 

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I had so many comebacks with Lucas flashers I made a test board with all correct wattage bulbs.

21w for turn bulbs, 3w for indicator.

Using spare 12v motorcycle battery (MotoBatt MB9U) with or without battery charger I can replicate idle or cruise voltage more or less.

This allows long term bench testing while I’m doing other things. Also allows me to experiment with the automotive flashers on the bench. I’ll gently use heat gun to warm flasher to what I feel on bike. Vibration I don’t test for. Hard to replicate that. That’s a problem too!

One thing I learned is a temperamental Lucas flasher is very hard to make reliable long term. Just when I’m sure it is actually fixed, it starts acting up. After spending hours & hours on Lucas flashers, I won’t install or try to repair them anymore. So Lucas flashers gave me a bad taste in my mouth to them. Personal experience not arm chair reading.
I hope they’ve improved.
Don
 

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Isn’t it cool how the indicator bulb works!

It gets its power from the flashing side. Gets its ground through the filaments of the non flashing side.

So it’s important the bulbs are correct & they are good & all bulbs are installed.

Never assume bulb is good by looking at filament. Test it with power. On rare occasion even an ohm meter will show good, but bulb won’t shine.

Our switches can get various problems. Most can be repaired. That’s another subject. I’ve repaired 4 so far including my own. Root problem is plastic shrinks leaving rivets loose. Rivets transfer power through circuit board. The loose creates resistance thus heat. Circuit board melts & contact points receded causing open circuit. If not too bad they can be repositioned , supported with epoxy. Then solder all rivets with low temp solder. Will last for years.
If I have to take switch apart for any reason I solder all the rivets to prevent future problems.

Working at Mercedes dealership 35 years this shrinking of plastic & loose rivets is very common in old age. I’ve soldered hundreds at work. A new circuit board cost more than the car was worth. Very few comebacks. This works!
Don
 

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Hi Steve,
I read here that there is a better Lucas and a worse one.
Motor vehicle Font Rectangle Gas Cylinder

Standard was 8FL. I've had better luck with the 9FL, that Lucas supplied to contemporary makers of other vehicles to work the flashers in 'hazard' mode. Slightly confusing is some sellers on the internet label the deeper 9FL, "8FL" ... :rolleyes:

can use a universal car flasher unit from an auto parts store
Problem I've found with those is flash speed varies with engine rpm - accelerating to join a motorway (freeway), the gap between bulb flashes is virtually invisible ... (n) YMMV.

signals stopped
Possibly too much strain on switchgear and connections
Best hope not ... a 21-Watt bulb draws 1.75 Amps, two draw 3.5A; even original Lucas 14-strand wire was rated for 7.5A.

indicator arms have to earth through the various bits they are bolted too as they have just the one wire into the lamp.
Ime, this is so often the fault with Lucas indicators (starting with the ones on my first Triumph over forty years ago), I add Red ground wires from the arms to nearby Red wires' snap connectors as a matter of course. Even if it doesn't solve an immediate issue, you still know grounding isn't the immediate issue, and it won't be in the future. (y)

But the fact the total system is dead, has me puzzled.
If any electrical circuit isn't complete all the way from battery -ve back to battery +ve, it will always appear "dead". If each flasher return isn't completing from its arm back to battery +ve, the circuits through the flashers aren't complete.

I'll refer to the wire diagram and start checking continuity.
Not exactly looking forward to setting aside four or five hours with a DVM.
Hardly. The flasher circuit:-

. starts battery -ve -> Brown/Blue wire -> ignition switch - this is common to all circuits so, if other electrical components are working, the fault isn't here;

. continues ignition switch -> White wire -> flasher relay - all White wires are 'hot' when the ignition switch is turned on so, if things like brake switches are working ... tip - if you look at the White wire connected to one flasher relay terminal, if there are actually two White wires crimped together in the female spade terminal, one is likely from the ignition switch, the other is likely to the rear brake switch;

. continues flasher relay -> Light Green/Brown wire -> handlebar switch;

. handlebar switch -> Green/Red wires -> left/drive-side flashers, handlebar switch -> Green/White wires -> right/timing-side flashers.

Assuming your meter is a multi-meter, to check for continuity:-

. set the meter to the lowest Ohms scale, connect the meter +ve lead end to the battery +ve terminal;

. start testing by first touching the meter -ve lead end to the battery -ve terminal and noting the battery Volts (so you know if the circuit has just lost Volts elsewhere);

. then touch the meter -ve lead end to each of the connections I've listed above (never disconnect any connection to test it) as far as each flasher bulb;

. once you've tested up to the flasher bulbs, connect the meter -ve lead end to the battery -ve terminal, disconnect the meter +ve lead end from the battery +ve terminal and use it to test the return connections from the flasher bulb back to the battery +ve terminal;

. when the meter displays either low Volts or no Volts, there's a fault between the connection you've just tested and the previous connection that tested 'good'.

Hth.

Regards,
 

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Discussion Starter · #20 · (Edited)
Hello Don, using a volt meter, I was able to verify the double white wire at the Flasher Unit is live. Additionally, the brake light does function. All bulbs and warning light are proper. Nevertheless when connecting the two White wires and the Lt Grn/Brown Flasher unit wires, nothing happens upon turning the ignition on and the signal switch activated.

I'll next attempt to verify continuity of the wires from the Flasher Unit to switch gear and onwards per StewartMac outline. Steve
 
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