Alternator noise or ground issue? - SOLVED

[gbullman]

I converted my running lights on my 66 to LEDs and in general they work well. Thanks to help from 66vairguy I have noticeable difference in brightness between the running lights and signal lights at each corner.

I'm finding the LEDs have other behavior that is more annoying than a problem but I'm looking for ways to take care of it.

With the engine off the running lights (no headlights) on all 4 corners are nice and steady and a good brightness for visibility. When applying brakes or turn signals there is a noticeable difference in brightness to get other driver's attention.

But with the engine running the taillights have a very noticeable flicker, the left worse than the right. After the engine has been running for a while (like 20-30 minutes or more) that flicker subsides, many times going away completely.

My theory is that when the alternator is working to charge the battery the non-perfect DC from the alternator is causing the LEDs to flicker. Once the battery is fully charged then the flicker goes away.

I'm thinking that an inline filter would remove this alternator noise but my only experience with doing that has been for radios which have easily isolated power supply and it's pretty easy to throw a filter on just for that purpose. With the running lights I kind of have to do the whole car or insert a filter in the feed for those lights.

My thought is to get a "filter" / DC to DC converter and install it between the alternator and the Chasis common positive feed (that little post with the affectionate name I can't remember). Since the alternator is a 37 Amp alternator thinking a 50+ Amp filter should be sufficient.

The thought has also crossed my mind that this could be a symptom of the infamous tail light ground quality and I'll try cleaning that up again before I go too far down the filter rabbit hole.

Anyone else running LEDs have issues with tail lights flickering. Brake and turn signals are fine, it is just the running lights that have this issue.

Thanks in advance for feedback.

[66vairguy]

Gary --- With some of the early LED bulbs I found that if ALL the bulbs (front turn and park, turn indicator in gauge cluster, and rear turn/brake and running were LED then there was no bleed off with the parking lights on and if you selected the turn function the rear LED's would not dim much to the running light level. The fix was to install a 1.1K ohm 1/2 watt resistor from brake/turn wire to ground on each side. NOTE: this is not an issue if the gauge cluster indicator bulbs are NOT LED.

As for you blinking problem --- I assume it does not happen with the engine off, just running off the battery.

YES a faulty ground will cause bizarre LED functions.

It is possible the alternator regulator is "pulsing" the voltage. You did not say if the alternator is the old 10DN external regulator, or a newer 10SI internal regulator. Also with the headlights on do you have the front "parking" lights wired to stay on (done at headlight switch by moving a wire).

Before "adding things", I would check the alternator and regulator. A failed diode in the alternator causes odd problems, and it will appear to charge, but not well. A digital meter will NOT see the issue. You need a diagnostic scope to look at the voltage level at the battery with the alternator running -- yeah I know not easy. The alternate is to make sure the battery is "healthy" and swap the alternator and voltage regulators for good parts. It is possible you LED's have developed a problem. They actually have a little circuit in them.

Finally -- LED's have changed over the last decade, even yearly!! I know use a brighter LED tail lamp bulb made by AUXITO a buddy recommended. China stuff, but they work well - so far! See https://www.auxito.com/collections/1157-led-bulb
Note: they are not like the old "corn cob" LED bulbs and have a lens on the top, but noticeably brighter than the old "Superbrite" LED bulbs I had.

[gbullman]

Bob,

I'm already doing the resistance to ground trick on all 4 turn signal leads and that has given me the noticeable difference in brightness between running lights and signal lights. Thanks again for that tip. I do have LEDs in the turn signal indicators in the dash but I really like them so looking for other solutions.

I think I'm going to start with cleaning up the ground contact surfaces on the tail lights since the parking lights don't exhibit the same behavior and are being fed by the same source. I have not modified the parking light behavior so they are off when the headlights are on.

Basically I want running lights because with the dark car and top down I get way too many people pulling out in front of me. I'd prefer not to run my halogens all the time when I'm driving the car and I went to LED running lights because I seem to leave the lights on more than is desired and figured LEDs would be less drain and as a bonus they are brighter.

Alternator is a rebuilt original, externally regulated with a solid state regulator from Clark's (actually both Alternator and Regulator are from Clark's). I think I may have a tester that detects diode issues so I'll check that out but doubt there is a problem in that area, no other symptoms of issues with the charging system.

You are the 2nd person to recommend those LEDs so I may give them a shot as well.

[66vairguy]

Bob,

I think I'm going to start with cleaning up the ground contact surfaces on the tail lights since the parking lights don't exhibit the same behavior and are being fed by the same source. I have not modified the parking light behavior so they are off when the headlights are on.

If you have the headlamp switch in "PARK" position to run both front and rear lamps and only the rear does blinks, then I think you are correct that it is not a voltage supply issue. When one tailamp has a bad ground it tries to feed back through the other bulb to ground. A incandescent bulb will be dim on one side, bright on the other. With LED's, it is hard to determine as most LED bulbs internal power regulator circuitry is not published.

Just a comment ----- I've had so many problems with Corvair EM and LM tailight intermittent grounds I now install ground wires from the bulb socket to chassis ground. Yes a PITA to do, but it is a one and done deal.

Let us know what you find.

[gbullman]

Removed the left tail light socket from the housing and the whole thing came apart (ground piece fell out of socket). When I got the car it had the same issue and I offset each serrate to get a little more grip on the plastic socket and that held up reasonably well for 4 1/2 years. Cleaned things up and used some epoxy to hold the ground piece in the socket (just around the serrated part).

Weather a little on the cool side so going to give the 5 minute epoxy a couple of hours to really set up and fingers crossed for now. I'll report back when I have it all back together and see if the flicker goes away.

I hear you on adding a ground wire and I may come to that, waiting to see how this less drastic fix works.

[66vairguy]

I have seen the "insert" slip up and then the bulb contacts on the end don't touch the socket contacts with enough tension and you get intermittent lights.

Years ago I discovered the auto parts stores rear LM sockets were JUNK. The metal socket ears were too flimsy so you lost ground or they FELL out of the tail light housing.

When I had M&H electrics make up a harness I asked them about it and they said the yes they had to have the China socket manufacturer make up parts with a heavier gauge metal. Unfortunately M&H does not sell the sockets separately.

[Wittsend]

... I now install ground wires from the bulb socket to chassis ground. Yes a PITA to do, but it is a one and done deal. ...

Agree 100%. I use a BIG OLE SOLDERING IRON like people use for lead windows and solder a wire to an elevated pinch weld and then the bulb housing. A hint, clean off the paint and establish a decent solder to the car itself - first. The body acts as a heat sink and even my BOSI is challenged. Then go back and solder the wire. The socket is far less of a heat sink and solders pretty easily.

In my opinion it is much less of a PITA to secure a ground premptively than at a far less advantageous time such as blistering heat, heavy rain, in the dark, the wife saying she needs to get to a rest room etc.. Plus..., if you are (still) having issues you know it isn't one of many grounds and can rule them out.

[Lane66Monza]

If you want your parking lights to be running lights (on withe the headlights). Move the purple wire in the switch connector from one terminal to another.

See the info in below link to see how it is done

viewtopic.php?p=152017&hilit=Headlight#p152017

[American Mel]

Don't change your front signals to running lights, UNTIL AFTER you get the flicker fixed.
Someone might just mistake that erratic flicker for a blinker and pull out in front of you.
btdt

[gbullman]

Solved! After cleaning up both tail light grounds and making sure the insert was secure I got the same flickering on both Left and Right tail lights instead of the left more pronounced than the right. The Parking lights remained steady so no issues there.

This was with the Superbright LEDs that I have been working with for the last couple of years. So I put in the Auxito Red bulb on the left side and that side stopped flickering but the right continued to. Changed out the right bulb as well and it went steady so problem solved. At that point I also put the Auxito Amber bulbs up front and now all are good. As a bonus the Auxito bulbs are noticeably brighter so I should be seen pretty well.

Apparently something with the Superbright bulb was not happy with my car.

Thanks for the advice.

[RexJohnson]

It would be interesting to try the old bulb in another car to see if it is the car or the bulb. Sometimes you can have a diode that allows too much thru the wrong way and you have a lot of AC current in the system. You can put a AC voltmeter on the battery and see what is happening. I believe there is a spec for allowable amounts but I do not know what it is. In '60's cars they would not be effect but with computers they don't like it too much.

[gbullman]

I'm thinking along those lines Rex. Electrical noise that did nothing to incandescent lamps and other non-digital electronics I'd be is present in most older cars. It is only when we try to use modern more sensitive technology that situations like this develop.

Right now I have the ground lead from the battery going through the base of the alternator support bracket, through the upper shroud into the block or head (outer bolts of shroud). There are star washers between each layer for better conductivity. The bracket then is bolted to the alternator. That bracket and bolting the alternator to the oil filter adapter are the only paths to ground for the alternator right now. I have debated running a ground wire from the chassis ground (from battery to chassis) to the ground lug on the alternator. Definitely won't hurt anything and may clean some stuff up.

I'm just happy I can now drive with my parking lights on and not offer confusing info. Nice bright amber lights up front and tail lights in back.

The Auxlito bulbs are noticeably brighter than other LEDs I have tried.

[jjohnsonjo]

Even good LEDS have a tendency to flicker as they get some hours on them. I installed a pair of eyebrow daytime running lights on my wifes KIA turbo optima. looked great for several years then then the flicking started. Solved it by getting her a K5 GT1 turbo mobile. They look great together.

20230211_144623_resized1.jpg (97.92 KiB) Viewed 364 times

[Lane66Monza]

These are my LED bulbs up front. As you can see i made the wire switch to have them on with headlights. I have clear lenses a CCF member had made for the owners wanting a set (reasonable cost). The bulbs are JDM switch-back 1157 bulbs, 100 watt equivalents. White for running lights and will go amber for turn signals. Great for daytime running lights. Just got to remember to turn then off. But, with all the LEDS on, in park light position, bulbs don't use much amperage. I left them on for 6 hours and still started the car.

These are my rear LEDs. Again, they are JDM 1157 red LED bulbs. Chiness bulbs would flash in a sequenceof 6 flashes then stop for 2 seconds and then repeat cycle, until engine was shut down. No noise filters in the cheap chinese bulbs. Those 6 flashes coincide with engine spark pulses.

You can see my blue instrument lights in this photo. License plate light is also a #56 9 smd bulb. But too many failures with the smds. You don't know when you have only one smd powered. When that goes, plate is in the dark and a reason for a road check by the LE. Bulbs are good enough for courtesy bulbs. But why buy them just to keep replacing them. I went through my 10 pack stock in 2 years. I found new ones and so far so good. No failures.

20191106_182632_resized.jpg (81.8 KiB) Viewed 350 times

These are the park light lenses I bought for my cars.

This photo shows the test I did with both sets of lenses. First in the garage lighted, then no lights and windows covered. This shows what the smoke lense are projecting, when bulbs are powered. My smoke colored lenses don't inhibit the illumination of the bulbs at all.

These are my backup lights. Not much illumination area like the 65, but the JDM 1156100 what bulbs provide plenty of light. These were just taken tonight from 30 ft away.

[66vairguy]

Solved! After cleaning up both tail light grounds and making sure the insert was secure I got the same flickering on both Left and Right tail lights instead of the left more pronounced than the right. The Parking lights remained steady so no issues there.

This was with the Superbright LEDs that I have been working with for the last couple of years. So I put in the Auxito Red bulb on the left side and that side stopped flickering but the right continued to. Changed out the right bulb as well and it went steady so problem solved. At that point I also put the Auxito Amber bulbs up front and now all are good. As a bonus the Auxito bulbs are noticeably brighter so I should be seen pretty well.

Apparently something with the Superbright bulb was not happy with my car.

Thanks for the advice.

Thanks for reporting back. Glad you like the AUXITO LED's Yes LED bulbs have a micro circuit that can fail. Unlike the old incandescent bulb that just quit, LEDS can malfunction so they flicker, get dim, and other issues before they quit.

[gbullman]

@Lane66Monza,

My primary reason for switching to LED Parking lights and Tail lights is less chance of running the battery down if I forget to turn the lights off. I feel like the amber parking lights are sufficient to get someone’s attention with their contrast to the dark car so that is all I turn on as “running lights”.

I’m fine with the original wiring of the parking lights going out when the headlights come on so not planning any changes there.

My headlights are halogens which are quite good for the few times I drive the car at night. So many of my friends won’t drive their classics at night which can be limiting on what you do with them. Hoping to do a drive-in movie sometime this summer which definitely involves some night driving.