Author Topic: LED Light Bulbs for FD RX7 (Read 2000 times)

PeakAlpha · « **on:** February 03, 2019, 05:37:47 PM »

Electrical Expert Dweebs,

I recently purchased two LED 1157 Light bulbs to try out on my FD RX7, and they are not working for me. I was at the track and a couple of people said that the outside brake lamps were difficult to see in the sunlight (go figure), so I decided to try and throw some (presumably brighter) LED bulbs in there so that my brake lights could dick-slap people in the face. So I plugged them into the sockets and I am getting precisely nothing. It says on the box that they work with most stock systems or some such. But I also read somewhere that I may need ballasts to get them to work. Anybody know what exactly I need to do to make these work? It is a racecar and I am pretty handy with electronics so I don't mind doing whatever needs to be done, I just don't know offhand what I need to make them work. Figured someone on this forum might know before I go totally apespit and do a ton of interwebs research.

Thanks all!

Cobranut · « **Reply #1 on:** February 03, 2019, 07:44:25 PM »

LED's have polarity, and must be forward biased to work.
I think most LED replacements have circuitry in them to allow them to work either way, but I'm not absolutely sure of that.
If your socket is wired with the polarity reversed, it may not work.

digitalsolo · « **Reply #2 on:** February 03, 2019, 10:29:02 PM »

Yep. That ^

Hard wire them to 12V and see if they work. If so, see what's up with the socket?

AV8rZ · « **Reply #3 on:** February 04, 2019, 12:05:11 PM »

Mine work fine. You can find them in my build thread if you’re interested

Sent from my iPhone using Tapatalk

PeakAlpha · « **Reply #4 on:** February 09, 2019, 11:01:39 PM »

Figured it out!!! Finally had time this weekend to sit down and look at this stuff. Turns out the problem is that I am stupid. Apparently when I was younger and (somehow) dumber, I decided to put +12V to the +12V for the lights, and ran ground to the +12V wire for the brake. No idea how the old regular bulbs were working, but based on my experimentation (measuring voltages) with the wires in that configuration, I am guessing that the brake bulbs were not getting 12V, probably around 6V. That would explain why they were hard to see before. Anyhoo, I got the things wired up correctly by ACTUALLY LOOKING at where the wires run to, and they work swell now. Since it is a race car and I want this shit to be obvious, I went ahead and wired both the running light filament and the brake light filament to +12V so they will both light up at the same time. They are now freakin PAINFUL to look at with the pedal pressed. The LED's on the other hand are not nearly as bright. I am actually pretty damn disappointed in those. Right now I am thinking that I will probably go back to regular bulbs for both sides since the LED's are so pathetic. I know that some other companies out there make bulbs with a lit-shoad of diodes (more than just the two on the Sylvania), so those might be brighter..? Anybody have experience with other bulbs than just the standard Sylvanias? Anyways, thanks for the advice guys. Helped me narrow it down faster.

AV8rZ · « **Reply #5 on:** February 10, 2019, 09:22:40 AM »

Quote from: PeakAlpha on February 09, 2019, 11:01:39 PM

Figured it out!!! Finally had time this weekend to sit down and look at this stuff. Turns out the problem is that I am stupid. Apparently when I was younger and (somehow) dumber, I decided to put +12V to the +12V for the lights, and ran ground to the +12V wire for the brake. No idea how the old regular bulbs were working, but based on my experimentation (measuring voltages) with the wires in that configuration, I am guessing that the brake bulbs were not getting 12V, probably around 6V. That would explain why they were hard to see before. Anyhoo, I got the things wired up correctly by ACTUALLY LOOKING at where the wires run to, and they work swell now. Since it is a race car and I want this shit to be obvious, I went ahead and wired both the running light filament and the brake light filament to +12V so they will both light up at the same time. They are now freakin PAINFUL to look at with the pedal pressed. The LED's on the other hand are not nearly as bright. I am actually pretty damn disappointed in those. Right now I am thinking that I will probably go back to regular bulbs for both sides since the LED's are so pathetic. I know that some other companies out there make bulbs with a lit-shoad of diodes (more than just the two on the Sylvania), so those might be brighter..? Anybody have experience with other bulbs than just the standard Sylvanias? Anyways, thanks for the advice guys. Helped me narrow it down faster.

As I stated before, my tail LED lights are very bright, much more than regular lights. They are in my build thread but I’ll save you time.