TR2/3/3A LED Flasher Problem

This morning I installed an electronic flasher for LED lighting: two front LEDs for turn signal/side head lights and two LEDs for the rear flashers. Once installed, all worked fine. The front LEDs flash amber and are white for side head. The rears flash red. I tested them by turning the ignition switch on and working the knobs/trafficator.

But when I started the motor, they didn't work fine: the dash light glowed steady, the front LEDs flashed erratically and the rear LEDs stayed on steady.

Any ideas?

Are you saying the front & rear turn signals came on even with the control in the 'off' position? Or just that they didn't flash as expected with the lever in either turn position?

If it's the latter, I'd guess your electronic flasher doesn't like all the electrical noise. Are you still positive ground? Do all new components match your ground polarity?

It's the latter symptom, Randall. I'm negative earth, having converted earlier when I put in LED stop lamps. All the components should be NE.

I would try either a different flasher, or adding some bypass capacitors at the flasher. Green wire connection to ground, a 10 mfd electrolytic plus a .01 mfd mica or ceramic should do it. Exact values aren't important.

As an experiment, you could try disabling the generator and then starting the engine. If the problem remains, it's most likely noise from the ignition. If not, then it's probably noise from the generator. Might be a sign of incipient generator failure, wouldn't hurt to have a look at the bushes and commutator; but most likely it's fine. They just make a lot of electrical noise. I've even been known to add a big ceramic cap at the generator output terminal, which cut way down on the noise getting into the CB radio.

Thanks again, Randall. I'll try a different flasher to verify operation, then see about adding the capacity. Why the two different types of capacitors?

I would hope the generator is OK, I just had a rebuilt one installed by Macy's, as part of my drivetrain overhaul.

Electrolytic capacitors (the larger value) are good at filtering low frequency noise; but not so good at filtering high frequency noise. The smaller capacitor will be much better for the high frequency stuff.

Every time the generator brushes cross a commutator segment, they cause a tiny spark. Also sparks inside the distributor cap, since the rotor doesn't quite touch the terminals. Sparks generate noise across a wide range of frequencies. It's hard to say (at least for me) just what range your flasher is sensitive to (if that's the problem at all). Hence the "shotgun" approach.

I appreciate the explanation. I tried another electronic flasher today with no change. So on to constructing the bypass capacitors. It might be awhile before I get to that, so in the meantime, I reverted back to Edison's, er Lucas' creations. I'll let you know the results when I do add the capacitors.

Another solution is to add load resistors, so the stock flasher will work with LEDs. That's the direction I went.

What resistors did you use and how are they wired in?

My setup is actually somewhat more complicated; since I also have 3 relays involved. Early cars like mine only had one brake light in the center, the rear corner lamps were originally only for tail and turn. Adding the relays allowed me to keep the center brake light, but also make the corner lamps do triple duty as brake/turn/tail, while still only having dual filament bulbs (or the LED equivalent of same).

Anyway, something like these should do fine for what you need
https://www.amazon.com/Resistors-Signal-License-Warning-Cancellor-x/dp/B004EDF8HY

One side of each resistor goes to the turn signal wire for left or right (GR and GW), the other side goes to ground.

You can pick out a mounting location; mine (and the relays) are mounted to a simple steel bracket which in turn is bolted to the back of the pedal box, under the dash. (Out of sight, plus no new holes.) The resistors do get warm in normal operation (while the turn signals are running), but not really hot. If you don't mind them being visible, on the inner fender near the LH horn (and near where the wires from the control head join the main harness) might be a good spot. On a LHD car, both GR and GW go through a 4-way bullet sleeve with only 3 of the openings used originally, so you can add a bullet to the resistor wires and connect them into the 4th opening.

Thanks again. I may give that a try.

I also see where George Hahn answered similarly, showing the resistors and wiring them up under the apron out of sight. See:

https://www.britishcarforum.com/bcf/showthread.php?106286-TR3-turn-signal-issue

His reply (no. 13) also shows a picture of what he did.

I was able to "fix" my problem. I went the route of adding resistors, the ones suggested by Randall. I used one resistor for each location, a total of four. I painted them with a red (to match the body work) high-heat enamel and epoxied small neodymium magnets to hold them. I replaced the wiring off each with the correct color-coded wire (GW, GR and black) and plugged them in. Using my stock flasher, they worked like a charm. While the electronic flasher was fun to do (disguising it in the original body), I would have had to capacitors to overcome the electrical noise. Adding resistors seemed like a better solution, plus they're more easily hidden.

Brilliant solutions: the color-coded wiring, the magnets, and using the extra bullet hole to connect in! Thanks —