TR2/3/3A TR3 turn indicator not flashing in car

[Adrio]

I have a problem with the turn indicator on my TR3. It works fine for the left side but on the right side the inside amber indicator only flashes once then stops flashing. The outside light flash just fine, it is just the indicator that does not flash.

I took some measurements and the 'good side' draws 3.011 amps while the 'bad side' draws 2.795 amps. This measurement was taken with the ammeter in place of the flasher unit, so it includes all wire and connector losses. I assume the lower current is not enough to make the flasher unit click over for the indicator light.

My question to the group is, has anyone solved this problem and if so where was the bad connection that is introducing the extra 0.41 ohms. I just thought that if someone has gone through this it would save me the trouble of going to every connector in the circuit and checking.

Thanks in advance.

Adrio

 

[TexasKnucklehead]

I'm looking at the wiring diagram, and that doesn't make any sence since the flasher unit is wired before the turn signal switch. It's the flasher unit that drives the warning light, regardless of left or right selection.

(So if the outside is blinking, the inside should be too.)

That's not a lot of difference in readings, but I'd be tempted to swap right turn bulbs with left ones, to see if the problem changes. -I bet your current readings are simply a result of slightly different bulbs.

 

[TR3driver]

I solved my problem by switching to a modern, "load insensitive" flasher /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

Not how you got 0.41 ohms ... assuming measurements were taken with a 12.0v source, I get more like 2.6 ohms difference.

Anyway, my real point is that the problem can be almost anywhere, from my experience. First place I would check is the ground for the RR turn lamp. After repeated problems with the grounds for the rear lamps, I built a ground harness for mine, with ground wires for all 5 lamps (which had bullet connectors for the ground on the bulb holders) all running to a ring terminal on one of the gas tank bolts.

Then check the ground for the RF turn lamp. It should be wired to a clip near the right horn, but the clips get painted, or broken. Even a good coat of paint under the clip can be a problem; so adding a 'star' lockwasher to the screw that holds the clip to the body is a good idea.

Also try replacing the bulbs themselves. Old bulbs can sometimes go up in resistance, as the filament erodes. Make sure the bulb types are the same from side to side as well, since there are multiple types (drawing different amounts of current) that will fit the holders.

Lots of other potential problem spots ... one person even wrote that they traced their similar problem to a wire that was corroded inside it's insulation enough to present significant resistance.

But if the above things don't show the problem, then I would try taking some more measurements, like checking the voltage at the bullet connectors near the horns, where the wires from the control head join the main wiring harness. If you see the same voltages here, then the problem is somewhere between that point and ground. But if the right voltage is lower, then it's the turn switch itself (in the control head) or the wiring to it (which can sometimes get damaged inside the head or where it enters the stator tube).

 

[Adrio]

Not how you got 0.41 ohms ... assuming measurements were taken with a 12.0v source, I get more like 2.6 ohms difference.

Randall,

I sent you a PM with my math. please correct it if I ma wrong

 

[TR3driver]

I sent you a PM with my math. please correct it if I ma wrong

Nope, I goofed that one ! D'oh !

 

[MGTF1250Dave]

Aloha Adrio,

I have a the same problem in my TR3A, except it is the left side that will not keep the interior amber light flashing. I haven't really dug into it, but I tend to think it is probably ground related. I have observed that if I rev the engine to about 1000+ RPM the warning light will resume flashing until I reduce engine speed to idle. I think the increased dynamo output voltage at higher than idle RPMs overcomes the problem of a poor ground or corroded connections.

 

[Adrio]

Aloha Adrio,
I think the increased dynamo output voltage at higher than idle RPMs overcomes the problem of a poor ground or corroded connections.

Aloha

I think that you are right that by reving the engine your higher dynamo voltage solves the problem. My theory as to why that is, is that the higher voltage results in a higher current and that solves the problem, even though the poor ground problem still exists. The flasher unit relies on current to heat up and function so if we don't have enough current we can get more by either raising voltage or lowering resistance. The later is accomplished by either reducing resistive loses in connections (ground or otherwise) or by increasing wattage of the bulbs.

I did a little experimenting/measuring tonight and found that the old bulbs (mine may have been from the 1950's for all I know) had slightly lower wattage then new ones I had in packages. By being selective on which bulbs I picked I was able to get both sides to flash. Though to be fair my correct flasher unit is not here right now and I am using a modern non electronic one (though the modern one was also only working on the left side before I changed the bulbs.

With the selected bulbs I was able to raise the current on the left side circuit from 2.795 Amps to 3.057 Amps. This is higher then the 3.011 Amps I had on the working left side before the bulb changes. Though I now have 3.112 Amps on the left side after the bulb change. Maybe the filament resistance goes up with age.

The whole system design is too high a Q for my liking when it is that sensitive to such small changes. But that is the allure of these old cars in my opinion. Anyone can buy something out of the box and use it. We get to tinker /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

I will know for sure tomorrow night when I get my correct flasher unit back.

 

[TR3driver]

Maybe the filament resistance goes up with age.

It does. The metal of the filament literally evaporates into the near-vacuum of the bulb. The thinner filament then has more resistance.

In some cases, the evaporated filament metal (tungsten mostly) will redeposit onto the (cooler) glass, giving the bulb a silver or black appearance.

 

[Adrio]

An Update

Indeed the new bulbs solved the problem. Tonight I put the flasher unit back in and made sure all my connections were clean. Both sides flash inside and outside the car. Thanks for all the help.

Randall, I agree about the filaments getting thinner. I suspect that is what happened.

Cheers,
Adrio