[C2] Correct current output at tail lights
08-25-2016, 02:26 PM
#1
Instructor
Thread Starter
Correct current output at tail lights
It all started with a "speedy" flashing -solved replacing the flasher- but then went into mystery as I tried to fit LED lights.
Basically the LED doesn't work properly as the isn't enough current on the brake/flasher hot wire -the best reading is 8v but it keeps fluctuating.
Any ideas on how to troubleshoot the lights wiring?
Thank you
Basically the LED doesn't work properly as the isn't enough current on the brake/flasher hot wire -the best reading is 8v but it keeps fluctuating.
Any ideas on how to troubleshoot the lights wiring?
Thank you
08-25-2016, 02:33 PM
#2
Safety Car
It all started with a "speedy" flashing -solved replacing the flasher- but then went into mystery as I tried to fit LED lights.
Basically the LED doesn't work properly as the isn't enough current on the brake/flasher hot wire -the best reading is 8v but it keeps fluctuating.
Any ideas on how to troubleshoot the lights wiring?
Thank you
Basically the LED doesn't work properly as the isn't enough current on the brake/flasher hot wire -the best reading is 8v but it keeps fluctuating.
Any ideas on how to troubleshoot the lights wiring?
Thank you
Regards, John Mcraw
08-26-2016, 12:29 AM
#3
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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Well i can eblaberate on LEDs if your asking. Something you need to realize is 8v is voltage not current. So if you lookup/google the data sheet you see an Red LED needs around only 2 volts using 20 milli amps (ma) of current and white LED needs 3.6 volts for the same 20ma current draw. And each color has a different current requirement. LEDs brightness is current dependent so running a white LED at 2 volts won't cut it and a Red LED at 3.6 volts gonna get real hot. I dont know what a flasher circuit even looks like but it reads like it is inadequate for driving an LED though 8 volts should be more than enough voltage - the current is not regulated. If you look enough you find a lot LED items powered by little 3.5 volt watch batteries like key chain items.
So how to use an LED for a indicator? Well the LEDs i have used for indication in prototype circuits had amplifier circuits with temperature compensation built in the voltage divider for the amplifier. So im assuming these plug and play LEDs on the market for 12 volts systems have quite a bit of circuit encapsulated and unseen. Yes, its hard to explain to other technicians that have installed 12 volt plug an play LED bulbs that the LED is current controlled - but it is. All they would have to do is google the data sheet for the LED they have to see the specifications called out.
So i guess what im saying is u need a controller to replace the "flasher" that provides the correct/stable voltage with enough current for your LEDs to work in the tail light.
Hope this helps.
So how to use an LED for a indicator? Well the LEDs i have used for indication in prototype circuits had amplifier circuits with temperature compensation built in the voltage divider for the amplifier. So im assuming these plug and play LEDs on the market for 12 volts systems have quite a bit of circuit encapsulated and unseen. Yes, its hard to explain to other technicians that have installed 12 volt plug an play LED bulbs that the LED is current controlled - but it is. All they would have to do is google the data sheet for the LED they have to see the specifications called out.
So i guess what im saying is u need a controller to replace the "flasher" that provides the correct/stable voltage with enough current for your LEDs to work in the tail light.
Hope this helps.
08-27-2016, 11:53 AM
#4
Instructor
Thread Starter
Let me give more details regarding a recent test.
I pulled the tail light socket to have a better access to the connections. I used a grounded wire for the ground and contacted the LED light to check what was wrong.
First of all, the ground is fine as it was direct to the frame.
The LED bulb was correctly placed over the positives connectors.
I tested 1 LED bulb while leaving all the others regular to avoid problems with the flasher not being a LED specific.
I turned on both directional lights and parking lights to check both circuits.
So, the flasher/brake was working as the other regular bulbs but the parking light didn't.
I turned the LED to invert the positives but it was still working with the flasher but not the parking lights.
My conclusion is that the LED light works fine in both the two circuits -bright and brighter- but there is something to do with the parking lights that doesn't make ti turn on.
I tried to check just the flasher and the parking light but got the same result.
BTW double checked with a regular bulb and it was working fine
I pulled the tail light socket to have a better access to the connections. I used a grounded wire for the ground and contacted the LED light to check what was wrong.
First of all, the ground is fine as it was direct to the frame.
The LED bulb was correctly placed over the positives connectors.
I tested 1 LED bulb while leaving all the others regular to avoid problems with the flasher not being a LED specific.
I turned on both directional lights and parking lights to check both circuits.
So, the flasher/brake was working as the other regular bulbs but the parking light didn't.
I turned the LED to invert the positives but it was still working with the flasher but not the parking lights.
My conclusion is that the LED light works fine in both the two circuits -bright and brighter- but there is something to do with the parking lights that doesn't make ti turn on.
I tried to check just the flasher and the parking light but got the same result.
BTW double checked with a regular bulb and it was working fine