rjglenn
Full Access Member
I bought some 3157 LED bulbs and my ABS light would come on and the cruise control quit working. Regular bulbs, no problem, LED bulbs, problem. Anybody know why?
RABS, cruise control, & LED bulbs
- Thread starter rjglenn
- Start date
not enough resistance in the brake light circut. measure the resistance threw the original bulb, then go to radioshack and get a resistor that ohms out to the same as the bulb. wire that inline for the brake light power.
rjglenn
Full Access Member
I understand about resistance, and I can understand how the wrong resistance could cause a fast flashing of the blinker, but what about the cruise control? Why would having LED bulbs make the cruise not work. If the bulbs are blown the cruise still works. Very strange to me. I went back to the regular bulbs
mblaney
Full Access Member
I think you have this backwards. Regular bulbs draw more power (current) than the LED's. Adding a resistor in parallel to the LED will simulate the load of a regular bulb and your stuff will work. The LED appears to be 'open' like a blown bulb, that is what is confusing the computer. Note, adding a resistor in series will cause a voltage drop across the LED and it will not work.
Measuring the resistance of a bulb filament won't be accurate as the resistance changes significantly when the filament heats up (like a glow plug). It would be very difficult to measure the resistance of a flashing bulb unless you can track current and voltage concurrently. I would just turn each filament on at a time, measure voltage and current, and calculate the resistance required. You can also calculate the same by knowing the wattage of the bulb filaments.
Measuring the resistance of a bulb filament won't be accurate as the resistance changes significantly when the filament heats up (like a glow plug). It would be very difficult to measure the resistance of a flashing bulb unless you can track current and voltage concurrently. I would just turn each filament on at a time, measure voltage and current, and calculate the resistance required. You can also calculate the same by knowing the wattage of the bulb filaments.
can always do like i did on my work truck, just wired a bulb in with the brake turn lamp. tucked it behind the housing. this slowed my signals back to normal, and the cruise works again. also this is on a 2007 chevy. but i have had the same problem with my 86 when i put leds in for brake lights.
