Hi guys. First, thank you for allowing me to post my question on this forums. I appreciate any help you guys can give me.

Let me start by saying that I have limited knowledge of circuits and electronics. I work as a physician, and as such I only have undergraduate level general physics as my electronics background, so this is probably a very basic question.

I converted a MKIV 1995 Toyota Supra's taillights from the standard halogen to a series of LEDs. The Supra has a taillamp failure sensor which illuminates a dash light telling you the taillights are out. As you might have figured out, it doesn't like the LEDs. I was hoping for some help to modify it to work correctly with the LEDs.

Here's some information I found from another website

Each burn out resistor denotes a channel. As 3p said each channel is a comparator circuit with one side connected to a reference voltage and the other connected through the burn out resistor. The output of each channel is connected to an OR gate. The output of the OR gate drives a transistor that controls the warning light. Pretty simple.

Each channel has a delay circuit of .5 seconds. The stop light channel has a latching circuit to keep the warning light on after the brake pedal is released. Don't hold me to it but I seem to recall a failure of the LED CHMSL on cars that have it will not be detected. I could be wrong though.

The Surpa has a 2 channel light failure module, one for the stop lights and one for the tail lights

Here are the circuit diagrams from the service manual:
For taillights (on when headlights are on)

For Stoplights (brake lights)

and some pictures of the device itself:

Clearly someone has swapped out the resistors. Originally the car used 1156 bulbs which are 19watt and have a resistance of 2.2ohms each, and half of the tail circuit (2 1156 bulbs running in parallel) has 1.3ohms resistance (as measured by the harness I have). It originally used a 2700k resistor in the circuit and a 6200k resistor in the other circuit for the brake lights.

Thanks again for your help. You may have to dumb-down your answers a little for me. If anyone has any medical questions, weird bloodwork, or rashs/bumps you want someone to look at, I'm your man! That stuff is easy, electronics just seems to elude me.

 

This board does not allow discussion of automotive modifications for safety reasons..
Sorry.

 

Hello DrTom,

As you can read in the site ToS, automotive modification topics are not allowed. Therefore this thread will be closed.

You might want to try asking on the sites listed on this thread:
http://forum.allaboutcircuits.com/showthread.php?t=54400