Headlights and Gauge Cluster not coming on

[0silversnake3]

Hey guys. I just installed LED lights everywhere on my 03 cobra, headlights, fog lights, taillights, reverse lights etc. (Raxiom Brand everything, installed the modified flasher relay as well to go with the sequential taillights).

The headlights and dash lights (gauge cluster) was working fine prior to installing the taillights. The taillights were the last thing I installed. After installing the taillights, when inside car to test everything and noticed my headlights and dash lights weren’t coming on, but everything else is working. If I pull the headlight switch all the way out, then push it in slightly, say about 1/8 of inch, headlights and dash lights come on but then start flickering of and on. I ordered a new headlight switch hoping that would fix my issue, but no luck. Exact same issue is still happening.

Any ideas??? Thanks in advance!!


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[Huachipato]

There is an old thread where this happened... If I recall correctly - there taillights you installed are not keeping the park lights and brake lights isolated. So in other words, each time you hit the brakes, it is trying to use that circuit to power up the headlights and dash. I think it has to do with the bulbs expecting a common hot instead of a common ground that our cars have. The fix requires some modifying of the cables - to add some Diodes to keep the current from flowing to the wrong circuit (if you really want to do it the hard but cheap way anyways) or buying a set of LED bulbs that others have tested and found to work well with our cars.

I should add, you can put the old bulbs back in just to make sure everything work properly and that the tail lights are in fact to blame for you issue.

I think that is the jist of it... I have LEDs all around (not Raxiom) and have not had any issues.

Taillights I use are Phillips Vision Red: https://amzn.to/2LEQyzb

Others use Osram without issue - and I think those are actually brighter. Here is another thread that might be helpful:
https://www.svtperformance.com/forums/threads/brightest-led-taillight-bulbs.1133133/

 

[Revvv]

Put the standard front signal/parking light bulbs back in and everything will work as it should. I have no idea what causes the parking lights to mess with the entire lighting system, but they do.

You may also be able to wire in a set of load resistors into the front parking lamps. If that works, let me know. I pulled my yellow LED lights after encountering the same issue.


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[Huachipato]

I disagree on adding resistors. On a simple circuit car like ours - the only issue you should encounter is the hyperflash which can be easily and quickly resolved with a different flasher.

Like I've said - several of us here on these forums have successfully made the switch to full LEDs without encountering the issues you are having. It has to do with getting the right bulbs.

Found another thread on the topic: https://www.svtperformance.com/forums/threads/led-bulb-questions.1113517/

In there I concluded this: DO NOT BUY CK Bulbs!

 

[Revvv]

I disagree on adding resistors. On a simple circuit car like ours - the only issue you should encounter is the hyperflash which can be easily and quickly resolved with a different flasher.

Like I've said - several of us here on these forums have successfully made the switch to full LEDs without encountering the issues you are having. It has to do with getting the right bulbs.

Found another thread on the topic: https://www.svtperformance.com/forums/threads/led-bulb-questions.1113517/

In there I concluded this: DO NOT BUY CK Bulbs!

It sounds like I need to experiment if I decide to mess with LEDs again in the future.

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[Revvv]

I actually installed the flasher relay for the LEDs as noted in the thread you posted. I still had the same problem the OP has. A friend of mine with an 04 Mustang also changed to LEDs and the front parking lamps made everything go crazy. Standard bulbs straightened things back out.

I want to run a set of switchback LEDs, and I am pretty sure my only option is going to be the installation of a load resistor.

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[Huachipato]

It really isn't that hard... I even have the sequential setup on my car. It's just a matter of getting the correct bulbs and making sure they are installed with the correct polarity. It really is that simple.

I would be surprised if the resistor did resolve your issue. The point of the resistor is the increase the load in Parallel with the LED bulb. The amount of power going through the bulb is the same - but you just add another path to essentially waste energy. The lack of a load should only cause hyper-flash in our cars when using the stock flasher. The issue you are describing is caused by the joining of 2 circuits together through the bulb. You have even identified where the issue is (tail lights).

Let me add - the only reason I can think of to use a resistor is if you have a car smart enough to detect when bulbs go bad. I have an old MB that likes to tell me all kinds of stuff like that - and using a lower power bulb (such as switching to LED) will make it trigger an error message in the dashboard. For those kinds of cars - sure - add a resistor. However - I like to say our Cobras have a simple circuit. There is no computer looking for bulb that may have burnt out. The only component in our car that cares is our stock Flasher. In our case there really is no reason to add a resistor since our cars quite frankly do not care if you lower or increase the wattage of any bulb.

 

[0silversnake3]

Here are the lights I bought for the rear, reverse and brake lights.

Here are the front turn signal bulbs I used.

I’m sorry but I forgot I had posted this and haven’t followed up to check and see if I’ve gotten any feedback. Thanks for responding.

I installed load resistors at my brake lights which were “prescribed” by American muscle and no luck. Just slowed down my blinkers waaaaay to much. I have no idea how to fix this other than going back all original bulbs. But I’ve seen folks that are running complete led setups. What am I missing here???


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[*Jay*]

Did you try using regular front turn signal bulbs with your LED rears??? I have the sequential harness with LED's and a amazon special EP27 relay with no issues and no load resistors. Those amber signal lights are pricey but if theyre causing your problem then...

 

[Revvv]

The issue you are describing is caused by the joining of 2 circuits together through the bulb.

I need to ask a dumb question.

Can you explain this further? What makes an incandescent 3157 bulb different from it's LED counterpart? I am trying to understand how a simple 3157 bulb can become complex in regard to it's circuitry, causing a massive malfunction within the lighting system of the car.



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[*Jay*]

I need to ask a dumb question.

Can you explain this further? What makes an incandescent 3157 bulb different from it's LED counterpart? I am trying to understand how a simple 3157 bulb can become complex in regard to it's circuitry, causing a massive malfunction within the lighting system of the car.

Easy explanation is because you can plug a CK bulb in backwards and the ground pins are oriented different. Have to look at the lighting schematic but when you add a sequential harness and CK type bulbs you can introduce issues because electronics operate on PFM (pure, freakin, magic). Its why you need to make sure all of your CK bulbs are oriented the same in the sockets.

 

[0silversnake3]

Did you try using regular front turn signal bulbs with your LED rears??? I have the sequential harness with LED's and a amazon special EP27 relay with no issues and no load resistors. Those amber signal lights are pricey but if theyre causing your problem then...

No I haven’t tried swapping out the amber fronts yet. I will try that and let you know if it works. I appreciate your help. It may be this weekend before I get back to looking into this.


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[0silversnake3]

Easy explanation is because you can plug a CK bulb in backwards and the ground pins are oriented different. Have to look at the lighting schematic but when you add a sequential harness and CK type bulbs you can introduce issues because electronics operate on PFM (pure, freakin, magic). Its why you need to make sure all of your CK bulbs are oriented the same in the sockets.

So are my bulbs I used the “CK” bulbs?? Is that what’s causing my issue? If mine are the CK bulbs, do I just need to make sure they are all the same direction and then I should be fine??


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[*Jay*]

Start with checking the amber LED bulb orientation, make sure they both match, then swap the fronts out back to stock if you dont fix your issue. If all of your red LEDs are lighting up correctly (parking, brake on, brake off) then they are oriented correctly.

 

[*Jay*]

So are my bulbs I used the “CK” bulbs??

Looked on AM and they didnt say, check the packaging and or the writing on the bulbs.

 

[Revvv]

Easy explanation is because you can plug a CK bulb in backwards and the ground pins are oriented different. Have to look at the lighting schematic but when you add a sequential harness and CK type bulbs you can introduce issues because electronics operate on PFM (pure, freakin, magic). Its why you need to make sure all of your CK bulbs are oriented the same in the sockets.

...and now the light bulb in my brain flickers. Thank you for the diagram. That clears things up.

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[Revvv]

Start with checking the amber LED bulb orientation, make sure they both match, then swap the fronts out back to stock if you dont fix your issue. If all of your red LEDs are lighting up correctly (parking, brake on, brake off) then they are oriented correctly.

This is where I am lost. I cannot run amber LEDs up front because they cause the dash, fog lights, etc to flash when they do. The bulbs are oriented correctly, otherwise they would not light up.

My understanding now is that the LED bulb is wired wrong, and is basically causing a nightmare. Am I wrong? If so, what is the correct LED replacement bulb number? How do I know, without trial and error, that the LED board is wired in the correct sequence?

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[Revvv]

Looked on AM and they didnt say, check the packaging and or the writing on the bulbs.

What is a CK bulb?

I may as well get every dumb question possible out of the way. Someone else will likely need the answers as well.

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[*Jay*]

A CK bulb base is just wired differently than a standard bulb base is all, look at that diagram again. Where a standard socket provides a ground a ck bulb expects the low volt input, where the ck bulb expects a ground the standard socket provides a low volt input. Depending on the complete circuit this is how weird things happen, grounds and volts going is strange directions.

Some LED bulbs can work as CK or standard, depending on how your car is wired these bulbs may or may not work. This is why I say check and make sure the amber LED bulbs are oriented the same.

 

[Revvv]

Now I am curious as to whether or not I can swap the wires in the base of the bulbs I have.

Boredom + me = experimentation and occasional chaos.

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