So I went and installed my LED back up, stop/turn/brake and front signal bulbs last night and ran into all sorts of weird stuff. With the lights off and pressing the brake, every single bulb would lights up, if the lights are on the signals wouldn't work, if the light switch is pulled to the first position and you hit the signal, both of them would start flashing, and the brake lights were just continuously bright, they wouldn't get brighter when I pressed the brakes.

Now before I end up removing and returning all these bulbs, can someone point me towards which relays I would need to install on my 68 to fix this issue? I've read here that I would have to replace one in the fuse panel and one that is behind the passenger dash panel? I've seen some that are round like the one currently in the fuse panel and they have a ground wire, and then ive seen square looking ones that have 2 or 3 prongs.

Which one of these would I need?

 

the ground wire you are referring to, are you sure the capacitor for the flasher hasnt broken off?
you refer to relays but the part in the fuse box and the part behind the dash are flashers.

 

Sorry I may be mistaken, but I believe you are correct in that I was referring the the LED flashers. The ground wire I'm referring to is from the LED flasher I saw in one of the threads here:

https://www.summitracing.com/int/parts/upd-90652/overview/?cm_mmc=pla-google-_-shopping-_-srese1-_-united-pacific

I just want to know which ones I would need to potentially correct all these issues that are occurring with the LED bulbs.

 

look at the existing flashers to see if they are two or three prong and order the appropriate ones from Summit

 

And just to make sure, its the one in the lower left corner of the fuse panel? Is it easy to spot behind the dash panel on the passenger side?

 

there is only one round flasher in the fuse box and the other one behind the passenger side dash is held on with a clip and pulls right out. Just look under the passenger side dash panel.

 

I saw on another thread where a member here said you have to cut one of the wires on each of the front sidelights and run it to ground. As I am changing over to LED also, I looked up the wiring diagram to see why that would be. The sidelights are not grounded.They have the brown wire running on the same circuit as the taillights and a light blue wire from the blinkers on the left and a dark blue on the right. This works with incandescent lights as it takes a bit of current to make them light, but the voltage feedback to the LED's makes light run when you don't want and not blink when you do want.

Just cut the light blue left and dark blue right and run the wire from the light to ground. Tape up the other end from the harness so it doesn't ground out on anything. The sidelights will light with headlights or parking lights, but will not blink.

And yes, you need the solid state flashers.

Mike

 

I read that as well but I'm not sure I want to start cutting up the harness.

I think what I'm going to attempt first is just remove the LED from the front parking light and see if that lets my reverse & brake/signal lights work properly. If that still doesn't work then I will end up getting the led flasher unit and probably attempt that mod to the side marker lights.

 

To point out what should be obvious. The flasher only controls the flashing of the signal lights so the wrong flasher just means the signals will either flash too fast, flash too slow or not flash at all. The wrong flasher will not cause the lights to malfunction as your describe.

So, start slow. Switch it back except leave out the small front marker bulbs. Try the backup lights and make sure they work. Then change the 2 outer tail light bulbs and see if they work or at least light the correct bulbs and have the correct intensity except possibly for the signal flashing speed. If that works, then try the main front bulbs and again make sure the correct bulb and intensity lights.

As for the side markers. Depending on the mode of operation, they can either use the other running lights or the signal lights as their ground. This means you can't run LED bulbs in them because the power switches polarity and they won't light in all modes. You can't run normal bulbs in them with LED bulbs in the other locations because the LED bulbs in the other locations don't have enough resistance to make them light. You could run normal bulbs if you used load resistors on both the signal and running light wires going to them or you could do as already suggested and turn them into running lights only.

 

lionel hutz is correct in taking it one step at a time. It sounds like you have ground issues. I have all my running lights and dash/ gauge lights converted over to LED and no problems. I didnt do my tail lights yet. On a 68 the hazard flasher is on the the fuse panel and the signal flasher should be under the center console near the cigarette lighter. LEDs dont operated off of resistance just 12 volts so any slight 12 volt source could light them up so if your other lights arent grounded well and the system is using the running lights as a source to ground, they would light up. I would check each system one at a time substituting in the LEDs

good luck

 

So I messed with the LEDs last night and made some progress.

I first removed just the back up bulbs and left the brake lights and front signals. When I hit the signal, the running lights would flicker a little and then the signal would flash, very, very slowly. I then removed the front signal LED and left just the tail/brake LED. This made the system operate correctly, the brakes lit up, signals worked fine.

I think this would mean that since the lights worked correctly with incandescent bulbs at the front, a LED flasher should fix my problem right?

The other thing I noticed about the 1157 tail light bulbs is that they are quite bright when they are on as tail lights, and when you press the brakes they don't get too much brighter. I'm going to see what they look like during darkness, as this could be a safety issue if it looks like my brake lights are on all the time.

 

Either your 1157 bulbs are jammed in backwards, the brake light part is burned out or you have a bad ground on those sockets. You could pull the brake bulbs and put the LEDs back in everywhere else and leave the brake sockets empty to see what you get

 

I thought LED bulbs can only be installed one way, if thy are installed incorrectly wouldn't they just not work at all? I'll try reinstalling them today and see if that makes any difference. I have not checked the grounds as of yet, that's next on the list.

 

Thanks, Mike! This is such an important post to understand. I just realized that I got ridiculously lucky and avoided this problem: I tied my front side lights into the LED Halos for my Dapper Lighting 575 LED Halo Hid Conversions and then wired the relays to the alternator. I ran a new ground strap from the block to the alternator to the front radiator ground spot just to shore up the grounds. I think I just "accidentally" avoided this issue because I was so paranoid about ground issues given all the pain that they can cause with EFI conversions. (Some people on here have made fun of me because I'm running dedicated ground wires all over the place like AC wiring, but I'd rather have multiple redundant grounds and GOOD grounds than have to chase these hard-to-troubleshoot issues when I could be doing a fun project.



Adam

 

If you had the side markers installed then they could be causing an issue. If there were no side markers installed then you still have another issue since the running lights should not come on with the signals.

As for the brake light brightness. The bulbs could be made backwards. Get someone to hold the brake pedal first and then turn on the lights. If the lights come on much brighter like the brake lights should then the bulbs are either in backwards or assembled backwards. It wouldn't surprise me since I've seen sockets for those bulbs with the wires color coded backwards.

 

I added several grounds to my car also. I cleaned all the stock connection points of the stock grounds and added new star washers and screws to them too. Grounds can be a huge issue on these cars.

Mike

 

The side marker bulbs are in there, I cant remember if they were working or not, i'll take a look today. Hopefully the bulbs are just inserted backwards and its an easy fix. I'll update once I get home.

 

Compounding my problems is that I decided to paint the frame all over so I have to grind the paint away under some of the ground straps -irritates my OCD, but it's probably for the best.


Adam

 

This might not be your issue but it's something to consider:


Here is what I use. Never failed me yet.


I just don't get the fascination with LED's. So they illuminate a few milliseconds faster and are a little brighter that incandescent........big deal. It's just not worth the frustration. I can find a hundred things that I'd rather get frustrated with and spend money on my car than LED's.
With that said I hope you fix your issue.

 

The first link you posted didn't work.

To be honest I just like that the LEDs are bright, butttttt if it turns into more of a headache than I want, I'll probably just put the regular bulbs back in.