A fix for fast blinking LED tail lights / turn signals - LotusTalk - The Lotus Cars Community
 
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post #1 of 11 (permalink) Old 11-21-2012, 03:09 PM Thread Starter
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A fix for fast blinking LED tail lights / turn signals

I fell victim to the fast blinker syndrome that many 2006+ Elise/Exiges seem to suffer from. LED's offer very high resistance (they are diodes) and so a "traditional" circuit will see this as a burned out bulb (since a burnt out filament also offers high resistance) and the traditional fail safe for that is to fast blink. So something causes the car to see the LED's for what they really are.

My car was well out of warranty, so getting a "free" fix wasn't an option. But at the same time I wanted to spend as little money as possible. Some have suggested using an LED aware relay, but I believe the relays are all in the Switch Pack Module (SPM) thats behind the dash. There are no user servicable parts in there. You can see pictures of it at the end of the post.

So I opted for the resistor method. This calls for putting a resistor between the RED and the BROWN wires on the harness for outer tail light assembly. While I found this worked, I noticed a strang behavior. Depending on whether the parking lights (and head lights as well) were on or off required a different value resistor to make the blinkers work right.

So my solution was to figure out which two resistances were needed. In my case ~22 ohms with the parking lights off and ~11 ohms with the lights on. I then wired a SPDT relay to the RED wire which feeds the parking light circuit.

The way it works is when the headlights are off the relay is connected to the 22 ohms resistor. But when the parking lights are turned on the RED wire gets 12V and energizes the relay causing the 11 ohm resistor to become active.

For all the parts required (outside of wire and soldering stuff which I have already) it was about $9 at a local electronics specialty store.

Heres a schematic of how its wired.



Video showing how it works.


I did try adding more resistance to power resistor thats included with the LED assembly, but it made no difference.

Heres a look at the circuit I made.






Heres the insides of the SPM



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post #2 of 11 (permalink) Old 11-21-2012, 04:47 PM
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nice looks clean, glad it worked

slwkart
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post #3 of 11 (permalink) Old 11-21-2012, 05:42 PM
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Awesome, my passenger side blinks fast so I will definitely give this a try. Luckily I will have the help of my dad who was a lead electrician at TRW

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post #4 of 11 (permalink) Old 11-21-2012, 06:27 PM
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Anyone have a broken or damaged led rear light? I will buy it.

Mine does this and I want to try to open one.


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post #5 of 11 (permalink) Old 11-21-2012, 06:53 PM Thread Starter
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Quote:
Originally Posted by Heavyweight View Post
Awesome, my passenger side blinks fast so I will definitely give this a try. Luckily I will have the help of my dad who was a lead electrician at TRW
Theres a name I haven't heard in a while. My Dad worked there in the 80's,back when the company still mattered
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post #6 of 11 (permalink) Old 11-21-2012, 08:21 PM
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yup, he worked at the el segundo facility for 23 years but left 2 years after they got bought by Northrup.

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post #7 of 11 (permalink) Old 03-09-2013, 07:27 PM
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Tell me what you think of this...I just picked up an '07 Exige with under 7k miles on her.

When I first drove it home, making a right turn, flicked the signal, and the blinker was blinking fast. I pull over at some point to check the lights, and everything on the right side was working as it should, just blinking fast. Then I flicked the signal to make a left, and the blinker was blinking normal, but 2 LED's were out on the outermost left tail lamp. So 2 LED's are out on the left side, and it's blinking normal, but the lights on the right are all working properly but are blinking fast.

Then I turn on the headlights and try again, and both left or right, the blinker is blinking fast in either direction. After a few minutes though, it goes back to the right side blinking fast (but all lights work properly), and the left side blinking normally (but 2 LED's are out on one lamp).

Makes sense? That's a head scratcher for me!

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'14 Scion iQ (to park damn near anywhere)
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post #8 of 11 (permalink) Old 03-18-2013, 05:56 PM Thread Starter
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Could be a failing Switch Pack Module (SPM). You might see if someone local will spend a couple hours with you swapping theirs with you. The SPM is behind the dash, not terribly hard to get to.
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post #9 of 11 (permalink) Old 06-15-2013, 03:12 PM
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Do you a part number for the SPM

Mine started doing today! blinks fine on the left but fast on the right....really annoying!

[B]05 Lotus Elise REV400, Stage II, BWR TB, OBX header, Moroso Oil Pan, RTD Brace, PRoAlloy Radiator, SS Break Lines, S111 Oil Catch Can, ACT HDC, Carbon Fiber Spliter, GRP Side Scoops, CF side skirts, , S111 front & rear tow hooks, tail lights-LED, Driving lights, Allitech, CF interior, 2010 Exige Spoiler, Lotus shop Seats, RA clam, Light Flywheel, ATI pulley, 2010 Exige Cup mirrors
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post #10 of 11 (permalink) Old 06-15-2013, 07:14 PM
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The cause is a defective resistor in the led unit.
Michael
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post #11 of 11 (permalink) Old 06-15-2013, 07:44 PM
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The LEDs all work in the taillight!

Quote:
Originally Posted by SirLotus View Post
The cause is a defective resistor in the led unit.
Michael
What else could it be?

[B]05 Lotus Elise REV400, Stage II, BWR TB, OBX header, Moroso Oil Pan, RTD Brace, PRoAlloy Radiator, SS Break Lines, S111 Oil Catch Can, ACT HDC, Carbon Fiber Spliter, GRP Side Scoops, CF side skirts, , S111 front & rear tow hooks, tail lights-LED, Driving lights, Allitech, CF interior, 2010 Exige Spoiler, Lotus shop Seats, RA clam, Light Flywheel, ATI pulley, 2010 Exige Cup mirrors
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