Patrick - LED Taillight problems

[DanEC]

Bob - to recap the earlier part of the thread - my tail lights and turn signals and brake lights all work fine with standard bulbs.

Installed the LED bulbs and the turn signal lights and brake lights work but the tail lights no longer lit up when lights are turned on.

Disconnected the lead at the tail lights for the turn signal and brake light circuit and then the tail lights worked (lit up) when lights turned on. Reconnect leads at tail light bulb holder for turn signal and brake lights and tail lights went off again.

Reversed leads on tail light bulb holder and tail lights worked OK with lights on (but burning on brighter bulb filitment). Turn signals and brake lights didn't work.

But to be clear - everything works just fine with 1157 or 2357 bulbs used.

Dan

[strictlypersonl]

Originally Posted by DanEC

Bob - to recap the earlier part of the thread - my tail lights and turn signals and brake lights all work fine with standard bulbs.

Installed the LED bulbs and the turn signal lights and brake lights work but the tail lights no longer lit up when lights are turned on.

Disconnected the lead at the tail lights for the turn signal and brake light circuit and then the tail lights worked (lit up) when lights turned on. Reconnect leads at tail light bulb holder for turn signal and brake lights and tail lights went off again.

Reversed leads on tail light bulb holder and tail lights worked OK with lights on (but burning on brighter bulb filitment). Turn signals and brake lights didn't work.

But to be clear - everything works just fine with 1157 or 2357 bulbs used.

Dan

If the the lights worked with standard bulbs, but not with the LEDs, the only conclusion I come up with is there is something wrong with the bulbs or their connections. Have you tried testing the bulbs when they are not in the socket?

[patrickt]

Originally Posted by strictlypersonl

If the the lights worked with standard bulbs, but not with the LEDs, the only conclusion I come up with is there is something wrong with the bulbs or their connections. Have you tried testing the bulbs when they are not in the socket?

... or, he has it goofily wired in such a way that, when everything is on, current is flowing in the opposite direction for the tail lights. That would explain why it lights with incandescent bulbs, but not LEDs.

[AL427SBF]

Much has been discussed here and on the LED tail light thread. Getting back to a baseline (patrickt) ...

- If you have the right LED part number
- Your wiring is standard for the Lucas rectangular tail light and front blinkers
- Your Lucas rectangular tail light and front blinkers are working fine now with the OEM bulbs

Then the 1157-R45-T LED should be a drop-in plug and play replacement right?

I'm going to assume DanEC's problems are unique to his setup in some way and most of us need not go down that rabbit hole in an attempt to get them to work.
.

[DanEC]

Originally Posted by strictlypersonl

If the the lights worked with standard bulbs, but not with the LEDs, the only conclusion I come up with is there is something wrong with the bulbs or their connections. Have you tried testing the bulbs when they are not in the socket?

Yes, I did extensively and both elements in both bulbs worked fine. I used a battery charger on the 2 amp setting to power them up. They are now installed in my 67 GTX and working fine.

[DanEC]

Originally Posted by patrickt

... or, he has it goofily wired in such a way that, when everything is on, current is flowing in the opposite direction for the tail lights. That would explain why it lights with incandescent bulbs, but not LEDs.

As you know, ERA wiring harness is all pre-fab and plug & play. Mine is a pretty straightforward car without any power options (radio, MSD equip, additional lights, ect. Only changes have been adding a lead for the Holley electric choke and only harness issues during build were two leads found reversed in one plug and needing to add a resister to energize the charging circuit.

But enough of this - hope they work fine in his car. They are significantly brighter.

[YerDugliness]

Originally Posted by glenview289

Some time back, about 3-4 years ago, I converted my Unique to LEDs. At that time there was discussion about the low current draw of LEDs that would notwork with some trailer relay switches. I'm sure a search on this will bring up something. Not an EE, but do remember this could be an issue.

Bill

I remember that thread...didn't the end result be that a resistor had to be added at the back of the car for the lights to work?

It's been a while, but there's that dim memory, perhaps I'll go back to the Unique website and see if I can find the thread.

Cheers!

Doug

[glenview289]

Here is what I found over on the Unique site. I used the Radiantz LEDs and they worked perfectly from the beginning. This was on a basic rolling chasis kit produced in 1992, long before LEDs were being used in cars. The trailer relay was "state of the art" at that time, whatever that means.

"Just a note regarding the use of the 48 LED bulbs made by Radiantz: You will need to use a "no load" solid state flasher with these bulbs, even if you use conventional bulbs in the front turn signals.

Edit: Most LED sellers tell you that you need a no load flasher when using LED bulbs. I've found that if you have incandescent bulbs in the front turn signals, you will still generate enough load to trigger the flasher. Always verify that your signals work when you make the change, just to be sure. So far everyone has been OK with the original flasher."

Link to the thread: LED Taillights that work!!

Bill

[patrickt]

The front bulbs were enough of a load to trigger my "normal" flasher. I did use a no-load on my four way flashers though. Remember though, the tail lights have absolutely nothing to do with the trailer relay, or the flasher, and that's what Dan was having problems with. It has to be a wiring/connection/ground issue for him. It's not going to be the need for a resistor either, which only acts to limit current flow. He's got the same 12.6v battery under the hood that everyone else does, and if his tail lights doesn't work with just the key turned on (and the engine not running), then limiting the current in the circuit with resistors is not going to make a difference. I just know if I had his car under my nose for five minutes I could tell what the problem was -- it's got to be something really, really simple that he's just looking past instead of seeing. It could be that the bolt that is at the back base of the trunk, and that acts as a common ground for the back light circuits, has its threads covered with goo or paint, and it's just barely grounding. But I think ol' Dan has thrown in the towel on getting LEDs to work on his car.

[Large Arbor]

I pulled the tigger on two LED bulbs today and will give it a try this week to see if it works. If it does, I will order two more.

Phil

[CJ428CJ]

If you're trying to switch to LED bulbs just for brighter brake and tail lights, you can use halogen bulbs instead. They work well with none of the flasher issues or other problems detailed in the above thread. Specs on the halogen bulb show that they are about 50W for the brake lights and 15 W for the tail lights compared to standard 1157 bulbs which are about 27W and 8W.

Eiko Light Bulbs - H4 Halogen - 12V - 50/15W - Mfg/N H1157 - Car

[Large Arbor]

Yes, I did see those. If the LED versions don't work I will go that route for more brightness. do however like electrical challenges and need something to do this winter along with asking Patrick many questions.

Phil

[DanEC]

Originally Posted by CJ428CJ

If you're trying to switch to LED bulbs just for brighter brake and tail lights, you can use halogen bulbs instead.

I take it that heat has not been a problem? No melting lenses?

[Xack]

Originally Posted by DanEC

Everything checks out. Bulbs light up in the light fixture using my battery charger. I reinstalled in my car and with my test light I show power at the connection but the bulb doesn't light. I checked polarity with a standard 1157 and they are the same. Only thought is that voltage off of battery is not sufficient to energize the LEDs on the tail light circuit - so next I'm going to wheel the car out and start it up and see if running voltage will light the tail light circuit.

If that doesn't work then I'll call superbightled since they haven't answered my email yet.

Edit - when I said polarity that was a misnomer. What I checked was orientation of the two illumination circuits and compared to a standard 1157 bulb.

What is your steady-state battery voltage? If you do not have 12-13 volts at the bulb, there is a resistance probably at the switch or between there and the bulb(s). Disconnect the battery and Check resistance on the LOW resistance setting on your VOM. Measure resistance between the bulb ground on the connector to the battery negative terminal. Also measure resistance between the bulb power and the connector on the load side of the light switch. Any resistance here will drop your voltage to the bulb(s). You should not see more than 1 or 2 OHMS of resistance in your wiring. LED's are voltage sensitive, meaning they will not light up if the source voltage is too low. They sink relatively low current compared to incandescent type bulbs. Incandescent bulbs (current sensitive) will turn on if they can sink enough current to glow the filament, even if source power voltage is low like 9 volts or so.

You can also run a wire from the battery ground and attach it to your bulb ground to see if you have a grounding problem. (I suspect a poor ground circuit) If you don't see improvement, the problem is on the power side, meaning you have a poor connection on the switch or any connection between the switch and the bulb filament(s). Check voltage at the fuse, switch, and all connections all the way to the bulb to see if you are getting anything but the same voltage measured at your battery (terminal to terminal).

[DanEC]

The car is down for winter maintenance items right now but it runs 14.5V at idle. ERA runs grounds from each tailight frames to a big bolt for the bumper brackets and I install serrated washers at all grounds. All are tight and I have multiple grounds installed from the drivetrain to the frame. Everything functions properly and is bright (for filiment bulbs). If I had ground problems I think it would show up in the blinker and brake light circuit also, which worked fine with the LED bulbs.

I mean the LED bulbs are working fine in my GTX with a 47 year old wiring harness, taillights and Mopars known reputation for electrical issues. A large number of these things burned up by the mid-70s due to electrical problems. If it was simply a bad ground or resistance issue that was the problem I can't explain how they could possibly function in my old Plymouth.

I appreciate the pointers. When I get the car out again and it warms up I may get out my meters and do some more checks on the tailight circuit. But I kind of wore myself out earlier, trying to fix something that wasn't obviously broken. I'm curious to see how Large Arbor does with them.

[strictlypersonl]

Originally Posted by DanEC

I take it that heat has not been a problem? No melting lenses?

(Re: Halogen bulbs)

It really shouldn't be a problem unless you keep your foot on the brake constantly. The parking light filament doesn't generate that much heat.

[CJ428CJ]

Originally Posted by DanEC

I take it that heat has not been a problem? No melting lenses?

I've used them for about 2 years now with no problems.

[Xack]

.....

[Xack]

Originally Posted by DanEC

The car is down for winter maintenance items right now but it runs 14.5V at idle. ERA runs grounds from each tailight frames to a big bolt for the bumper brackets and I install serrated washers at all grounds. All are tight and I have multiple grounds installed from the drivetrain to the frame. Everything functions properly and is bright (for filiment bulbs). If I had ground problems I think it would show up in the blinker and brake light circuit also, which worked fine with the LED bulbs.

I mean the LED bulbs are working fine in my GTX with a 47 year old wiring harness, taillights and Mopars known reputation for electrical issues. A large number of these things burned up by the mid-70s due to electrical problems. If it was simply a bad ground or resistance issue that was the problem I can't explain how they could possibly function in my old Plymouth.

I appreciate the pointers. When I get the car out again and it warms up I may get out my meters and do some more checks on the tailight circuit. But I kind of wore myself out earlier, trying to fix something that wasn't obviously broken. I'm curious to see how Large Arbor does with them.

Ok. But you've only proved the bulbs work by putting them in another car. That's good, but your problem still exists on your Cobra. The bulbs are good. The circuit works as long as your battery charger provides higher voltage than is available by just your battery alone. New washers don't mean you've fixed a bad ground.
Good luck!

[kevins2]

Has anyone tried the LED lights with the double round taillights? That'd require 4 bulbs, so somewhat pricy. I think the Halogen bulbs may be the way to go and may actually be even brighter. Gotta do some more reading first...