Technical Information for LED-R-US Products
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  1. Disable your '97 to '00 TJ Flasher "Lamp Out" Detector for LED Tail Light Installation
  2. Disable your '01 and Newer TJ Flasher "Lamp Out" Detector for LED Tail Light Installation

 

hDisable your '97 to '00 TJ Flasher "Lamp Out" Detector for LED Tail Light Installation
Scott Bessel came up with a real slick way to solve the flasher problem on his TJ after he installed his LED tail lights....
(Scott, Thanks for letting Mesa 4x4 put your solution up.)
I was unhappy with all the fixes for the fast blinker rate; I refused to put resistors in line to solve the problem. After a few blown fuses and some experimentation I have found an easy way to disable the lamp out detector in the flasher, thus eliminating the fast flash rate. I found that most just added the resistors, but no one seemed to actually fix the flasher.

What I did was to eliminate the lamp failure detector circuit. I didn't want or need this circuit with LED lamps, this was the best answer.

Simple steps: (This works on my '00 TJ, your mileage may vary)

Remove the electronic flasher
Remove the flasher cover, a small screwdriver and some careful prying makes this happen.
Cut the trace coming from pin 7 of the chip.
Replace cover
Install flasher

You are finished.

Information on the U643B chip used in the electronic flasher here:
http://www.atmel.com/dyn/resources/prod_documents/doc4727.pdf

I did find out that the Triden Stant EP26 is an exact replacement for the factory flasher, and is identical inside, and easily found for ~$12.00 at your local auto parts store.
Click on image for a larger picture.
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hDisable your '01 and Newer TJ Flasher "Lamp Out" Detector for LED Tail Light Installation
When Jeep decided to make a change to their electronic flasher circuit for 2001 and newer TJs, George Gillespie stepped up to the plate. Here is his fix to disable the "Lamp Out" detector circuit.
(George, Thanks for letting Mesa 4x4 put your solution up.)
Technical Information:
"The manufacturer of the flasher changed the IC used in the '01 and up version of the flasher. I contacted Atmel with a documentation request for the new chip, but was told it was proprietary customer-only information. I traced out the circuit and tried deactivating lamp out detection by cutting traces, but my attempts were unsuccessful. The '01 FSM turn signal page revealed the hazard switch function was bypassing frequency doubling to allow lamps to cycle at a normal rate regardless of a lamp out condition.

When depressed, the hazard switch bypasses frequency doubling by taking the L91 contact to ground through the GND contact. L91 goes to pin 6 of the IC through a 470 ohm resistor. I measured 13.7VDC at pin 6 which turns out to be about 30mA of current. The Radio Shack 275-241 relay is rated at 1A and fits nicely inside the flasher enclosure.

How it works:
- 12VDC from the IGN contact energizes the relay coil.
- The Normally Open contact closes taking L91 to GND.
- Frequency doubling is disabled.

Turn signals only work when the ignition is on.
The hazard function works normally.

I had a lot of fun working to solve the need to disable the frequency doubling mode of the flasher. It gave me a chance to fiddle some more with electronics, learn a bit more of the Visio software program, dig around my Jeep and most of all to contribute to the Jeep community. I have benefited so much from the great wealth of shared knowledge, it makes me feel good to think I have contributed, even in a small way."

Simple steps:
1) Remove the electronic flasher, it is located on top of the steering column.
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2) Remove the flasher cover, a small screwdriver and some careful prying makes this happen.
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3) Go to Radio Shack and get a 275-241 relay, fine tune your soldering skills, and prepare to make the modification.
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4) Your finished product should look something like this:
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5) Verify your connections, check for possible short circuits, re-install the cover.

6) Install flasher

You are finished.

 

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