Join Date: Oct 2015
Model: GL1500SE Euro Spec
GL1500 LED Tail/Brake Light Conversion Cancels Cruise Control Problem Solved
Today, I have completed diode and resistor modification of the LEDs and replaced 4 rear tail/brake lights with these LEDs.
They have worked quite fine, no problem, and the brightness of them were better than regular bulbs. Especially the red color of them fit perfectly.
And also I checked the cruise control, it is functioning perfectly, no problem.
Here is my conclusion about the led and its effects on the cruise control system.
As I have read many threads about this issue, many people have had problems and some of them given up using them. During my study and tests on this issue, I have found that the problem is the leaking positive voltage of the tail light to the brake light end through built in resistors which causes the cruise control to disengage or never engage. As a solution I have added a 1N4001 diode to the brake light end for each bulb to prevent this voltage leakeage.
And another problem was the heat built up which toasts the built in resistor. I have replaced the built in 47ohm 1/4 watt resistor with a 47 ohm 3W one on the tail light end.
I have done the modification inside the bulb case, and tested the heat built up. The picture of the modification and the maximum temperatures that I measured are given below.
As a recommendation I have to say; if you are not familiar with electronics dont try to do this by yourself, instead you may find proper led bulbs which have built in diodes.
When to buy a led bulb, grab a multimeter and measure the resistances between the contacts to understand the existence of diodes. If the reading between tail and brake positive ends (at the bottom of the bulb) is O.L it will mean that there is a diode between them which will prevent voltage leakage.
If you have a look at the temp table, the temp of LED (modified) is almost less than a regular bulb. The temp at the lead is slightly higher at tail light mode, but lower than brake light mode (48<61<91 in C) or (118<142<196).
I would prefer to use a 5W resistor for less heat up, but I could not find a small size for the bulb case, I am sure this one will be safe as well.
And if you will add the diode on the brake cable instead of inside of bulb case; use a higher amperage diode for safety, thinking someone else later may try to use a regular bulb which will draw higher current.