Gremlins in the blinkers. And side marker lights. And...

[Cleveland Crush]

RC92234, may I ask where you bought your LED's? It could be that if you bought cheapo bulbs off good ol' epay, they are not good. I learned this lesson early on when I started to convert all my lights to LED/SMD's. That's when I found Bill at HiPoParts.com and he helped solve the issues with expert knowledge and excellent parts.
On the dash turn signal indicators, you either have one bulb in backwards, a bad circuit board connection, or the wrong bulb type. It is possible that the printed circuit board is bad as well. As said, I'm no electrical expert by a long shot, but I had issues with this as well, just not as bad. My car has idiot lights, so there is ONE BULB that MUST remain an incandescent #94 at that is at the ALT position. This is critical!! (it's the only non LED bulb on my car anywhere). I suggest start with one issue, figure that our and move to the next.
I realize 73 wiring may be a lot different to the 71/72's, but in general, I think the principle is the same. Good luck, hope you get it sorted soon.

Stanglover,
Question concering your LED dash lights; I've converted my 72 dash to LED lights with excellent results EXCEPT the lighter, wiper and headlight bezel LED bulbs (different size bulb compared to dash bulbs) will not illuminate. If I put the stock incandescent back in the three bezel lights are fine. The polarity was good when I tried the LED bulbs. Did you incounter this non illuminating issue with your LED conversion??
Thanks,
Chris

 

[midlife]

Stanglover,
Question concering your LED dash lights; I've converted my 72 dash to LED lights with excellent results EXCEPT the lighter, wiper and headlight bezel LED bulbs (different size bulb compared to dash bulbs) will not illuminate. If I put the stock incandescent back in the three bezel lights are fine. The polarity was good when I tried the LED bulbs. Did you incounter this non illuminating issue with your LED conversion??
Thanks,
Chris

Those three bulbs have opposite polarity from dash lamps.

 

[Cleveland Crush]

Those three bulbs have opposite polarity from dash lamps.

10-4 Thanks

 

[RC92234]

Was having oil pressure issues and took the car in for that and while there I had them try to fix the non-working blinkers as well. This thread picks up on the electrics.

Background: although they didn't work prior, I had switched all the small bulbs (i.e,, everything but headlights) over to LEDs and grounded/LED flashing units. I checked continuity on every connection I could access and found no issues. I had also replaced the turn signal switch in the column because it didn't self-cancel when signaling left (replacing the switch made no diff in the blinkers not working, but it does self-cancel now).

While yes, they did (sorta) get the blinkers to blink, I confess their work on this issue gives me pause on the wisdom of the shop; first thing they did was to switch back to incandescents (which changed nothing). I need to chat w/the mechanic, not just the owner, to find out what they did because they did make progress in getting the blinkers working, just not as well as they think they did: they only blink during the day.

What I mean is that yes, left and right finally blink, but when you turn on parking or headlights, no blink. And while I hadn't asked them to also fix the flickering dash lights (has a new circuit board, new IVF and all new LED replacement bulbs), I'd hope a blinker fix solved that problem, too. It didn't.

I'm open to any and all suggestions at this point. I'm first going to put back the LEDs they switched out and see if that makes any difference. And, I replaced the headlight switch although I suspect even though purchased as new, it was previously used (the rheostat? wire was worn). At least I *can* use my blinkers during daytime when the headlights are not on.

Now I'm seriously thinking of going full monty and replacing the wiring harness. I tested at every bulb and found no continuity issue, and I had a pro working on it for two days and only got one interim step forward. Do y'all think that would address the issue, and with what certainty? (for sure, maybe, not at all). I'm not convinced that's the only possible solution but it might be a big hop-skip-jump over finding the (one or more) shorts.

 

[midlife]

Stick with incandescent bulbs while trouble-shooting. LED's can be polarized, which if they are inserted incorrectly, they won't function well.
Your problem has to do with your running lights enabled, and that somehow that's affecting your turn signals. Usually, that's due to a bad ground, or the wrong bulb in the proper socket. When you say the turn signals don't work, does it happen all around the car, or only at one position?

I'd unplug all bulbs in the rear (including side marker lamps), and see if things work correctly up front. This helps to isolate the problem. If OK, plug one bulb in at a time at the rear and see how things react. When it goes sour, that socket is the problem child (or the wiring to it). The back grounding is the worst of all Mustang years, which is why I have you start at the front.

 

[RC92234]

I'd unplug all bulbs in the rear (including side marker lamps), and see if things work correctly up front. This helps to isolate the problem. If OK, plug one bulb in at a time at the rear and see how things react. When it goes sour, that socket is the problem child (or the wiring to it). The back grounding is the worst of all Mustang years, which is why I have you start at the front.

Alrighty then and thanks! At least that's something that hasn't been tried: testing front and rear separately.
But I don't understand this: "When you say the turn signals don't work, does it happen all around the car, or only at one position?" I mean there is no blinking. Each side, front, dashboard and rear, lights up when the turn signal stalk is moved to that position, but, they don't blink.

 

[midlife]

Alrighty then and thanks! At least that's something that hasn't been tried: testing front and rear separately.
But I don't understand this: "When you say the turn signals don't work, does it happen all around the car, or only at one position?" I mean there is no blinking. Each side, front, dashboard and rear, lights up when the turn signal stalk is moved to that position, but, they don't blink.

That's one of the answers I was looking for. That basically says there's too high an impedance (e.g. a bulb out somewhere or a bad ground) that's throwing off the blinking. Again, work front or back first to help isolate the problem.

 

[mrgmhale]

If you installed LED lights in place of the conventional incandescent bulbs for the turn signal lights, the LEDs do not require nearly as much power that the incandescent bulbs can cause. Almost any time you replace any of the incandescent turn signal bulbs you will ned to replace the turn signal flashes and emergency light flashers with electronic units. You can get electronic flasher from most auto parts stores. Or you can order a set from the following link for very low price from:

https://www.vintageleds.com/store/c15/Flashers_and_Gaskets.html.
Following is a YouTube video Lynda and I put out together that shows where the flashers are located in First Generation Mustangs and Cougars. It also shows how to properly install and ground the electronic flashers:

 

[RC92234]

If you installed LED lights in place of the conventional incandescent bulbs for the turn signal lights, the LEDs do not require nearly as much power that the incandescent bulbs can cause. Almost any time you replace any of the incandescent turn signal bulbs you will ned to replace the turn signal flashes and emergency light flashers with electronic units. You can get electronic flasher from most auto parts stores. Or you can order a set from the following link for very low price from:

https://www.vintageleds.com/store/c15/Flashers_and_Gaskets.html.
Following is a YouTube video Lynda and I put out together that shows where the flashers are located in First Generation Mustangs and Cougars. It also shows how to properly install and ground the electronic flashers:

Thanks, but yes, I had already done that. After the shop replaced my LEDs with incandescents, they left the electronic units in place.

 

[1973grandeklar]

First rule: Do not feed the gremlins after midnight!
Second, re-check the installation of the new turn signal in the steering column. Reading back through, you found bare wires in the old one and this might have been the original issue. May not have been shorting directly to ground on the steering column, but shorting through a path to ground (the other light was dim when the desired light was bright). Then replacement opened up a whole new set or issues.
I cannot tell you how many times I "fixed" an issue and then a new problem appeared that I thought was still the old problem only to discover that the old problem was fixed and I am now working to correct a new problem and the whole problem just sent me into a rampage and wanting to just sell the darn thing.
Third: Do not get the gremlins wet! Water also tends to be a bad thing. Check the connectors for the main harness going to the back and front of the car. This is at the firewall. Hidden corrosion is also a real pain to find (because it is hidden).

 

[Stanglover]

Electronics and me are like oil and water, but (and I think I've mentioned this before) when I did my conversion to all LED's I too had issues with turn signals. I had installed standard electronic flashers, turn and hazard, but had non working signals. That's when I contacted Bill at HiPo Parts Garage ( www.hipoparts.com ) as I bought all my bulbs from him. What he told me was I needed a special grounded flasher for both turn and hazard signals. After buying these, I still had no turn signals and now I was really confused. Talked to Bill again and that's when I found MY problem (not saying it's yours though). Back when these harnesses were made, turn signal polarity was not a concern, so it really didn't matter if someone got the terminals installed wrong at the flasher sockets. That is indeed what I found. As I had no tool to remove and reinstall the wires correctly, I simply made up a couple of short jumper wires to connect correctly. Once done, turn signals all worked as they should and no problem since.
I know you said you installed grounded flashers and I may be repeating myself here, but check that the + and - wires to the flasher are indeed correctly connected. I'm guessing that when the mechanic reinstalled incandescent bulbs, the polarity was no longer the issue and why they seemed to work.

 

[RC92234]

Electronics and me are like oil and water, but (and I think I've mentioned this before) when I did my conversion to all LED's I too had issues with turn signals. I had installed standard electronic flashers, turn and hazard, but had non working signals. That's when I contacted Bill at HiPo Parts Garage ( www.hipoparts.com ) as I bought all my bulbs from him. What he told me was I needed a special grounded flasher for both turn and hazard signals. After buying these, I still had no turn signals and now I was really confused. Talked to Bill again and that's when I found MY problem (not saying it's yours though). Back when these harnesses were made, turn signal polarity was not a concern, so it really didn't matter if someone got the terminals installed wrong at the flasher sockets. That is indeed what I found. As I had no tool to remove and reinstall the wires correctly, I simply made up a couple of short jumper wires to connect correctly. Once done, turn signals all worked as they should and no problem since.
I know you said you installed grounded flashers and I may be repeating myself here, but check that the + and - wires to the flasher are indeed correctly connected. I'm guessing that when the mechanic reinstalled incandescent bulbs, the polarity was no longer the issue and why they seemed to work.

Actually, led-flashers with a ground *and* short jumpers that switch polarity are indeed in place.

What happened was the (original) spare tire/wheel was not secured and had shifted just enough to push the parking light feed into the ground on just one side, which explains why they worked without the parking/headlights on but with headlights on, thing went amok.

 

[Stanglover]

Actually, led-flashers with a ground *and* short jumpers that switch polarity are indeed in place.

What happened was the (original) spare tire/wheel was not secured and had shifted just enough to push the parking light feed into the ground on just one side, which explains why they worked without the parking/headlights on but with headlights on, thing went amok.

RC, yes, now I remember you did the jumpers on a grounded flasher.
As for what happened, wow, that's definitely a weird situation. Glad you found that out.

 

[MaddMike]

Electronics and me are like oil and water, but (and I think I've mentioned this before) when I did my conversion to all LED's I too had issues with turn signals. I had installed standard electronic flashers, turn and hazard, but had non working signals. That's when I contacted Bill at HiPo Parts Garage ( www.hipoparts.com ) as I bought all my bulbs from him. What he told me was I needed a special grounded flasher for both turn and hazard signals. After buying these, I still had no turn signals and now I was really confused. Talked to Bill again and that's when I found MY problem (not saying it's yours though). Back when these harnesses were made, turn signal polarity was not a concern, so it really didn't matter if someone got the terminals installed wrong at the flasher sockets. That is indeed what I found. As I had no tool to remove and reinstall the wires correctly, I simply made up a couple of short jumper wires to connect correctly. Once done, turn signals all worked as they should and no problem since.
I know you said you installed grounded flashers and I may be repeating myself here, but check that the + and - wires to the flasher are indeed correctly connected. I'm guessing that when the mechanic reinstalled incandescent bulbs, the polarity was no longer the issue and why they seemed to work.

Hello, I just installed LED Tail lights, Back-up lights and front turn signals. I had already switched the side markers and headlights to LED and will soon replace the dash lights. HOWEVER, I have the same problem - the parking lights and tail lights function but I have no emergency flashers and have no turn signal function. I installed the little black cube relays and grounded them. I read your post above. I too got my stuff from Bill at Hi-Po. My question is, what do you mean when you refer to jumpers? You mention short jumper wires sorry if I seem "dim" (pun intended). Can you elaborate?

 

[Stanglover]

Hello, I just installed LED Tail lights, Back-up lights and front turn signals. I had already switched the side markers and headlights to LED and will soon replace the dash lights. HOWEVER, I have the same problem - the parking lights and tail lights function but I have no emergency flashers and have no turn signal function. I installed the little black cube relays and grounded them. I read your post above. I too got my stuff from Bill at Hi-Po. My question is, what do you mean when you refer to jumpers? You mention short jumper wires sorry if I seem "dim" (pun intended). Can you elaborate?

Hello Mike,
Here's a pic of what I did. You may need to do this on both flashers. Actually I don't remember if I needed to do the 4 ways or not. Give this a try and hopefully you'll be good to go. Other than that, I have no idea. Without going back over the whole post, I assume signals worked before with incandescent bulbs.
I hope this works. It's so frustrating when things ought to work, but don't.

 

[MaddMike]

Hello Mike,
Here's a pic of what I did. You may need to do this on both flashers. Actually I don't remember if I needed to do the 4 ways or not. Give this a try and hopefully you'll be good to go. Other than that, I have no idea. Without going back over the whole post, I assume signals worked before with incandescent bulbs.
I hope this works. It's so frustrating when things ought to work, but don't.

Hi Geoff,
Those look like the replacement fuse relays - I replaced each, the turn signal fuse and the emerg flasher fuse. So are you saying you added two more with the extender wires to each tail light - using 4, two behind the dahs and one each at the tail lights?

 

[Stanglover]

Hi Geoff,
Those look like the replacement fuse relays - I replaced each, the turn signal fuse and the emerg flasher fuse. So are you saying you added two more with the extender wires to each tail light - using 4, two behind the dahs and one each at the tail lights?

Those are the grounded LED flashers I bought from Bill. I did not replace any fuses and in fact didn't know there were any.

 

[MaddMike]

Those are the grounded LED flashers I bought from Bill. I did not replace any fuses and in fact didn't know there were any.

Fuses whoops, I meant to say the round drum flasher unit - one for the signals and other for the emergency flashers. I figured it out, thanks, the info was helpful.