Q I thought it would be a cool idea to upgrade my tail, stop, and turn lights with LED replacements so they’d be brighter. The first set of LED bulbs I tried didn’t get bright enough when the brakes were pressed so I returned them. The second set are OK except my turn signals flash really fast. Is this normal or OK? I can try a third set, but’s a pain to remove my lenses to change the bulbs. Suggestions please?
A Welcome to the club! Some imported/aftermarket LED multifilament retrofit bulbs are poorly designed causing problems with socket fit, excessive length (conflicts with lens), poor brightness separation, flickering, and premature burn-out. Assuming one finds a workable pair of bulbs that differ noticeably in brightness between tail and stop, the next hurdle is a situation with turn signals called hyper blinking. This isn’t a fault with the LED bulb other than it draws much less electrical current than the incandescent bulb it replaced from the electrical system and confuses the lighting control system.
Older vehicles would flash turn signals slowly or not at all when a bulb burned out because of the nature of the primitive thermal flasher used. This annoying but useful characteristic alerted one pretty quickly that something was amiss. When electronic flashers were developed this same characteristic was kept, likely for safety reasons, but the flash rate was increased, instead of decreased. Your LED lamps, even though they are quite bright, likely draw about ¼ the current, or less, of the original bulbs, somewhat imitating a failed bulb. Many newer vehicles may also set trouble codes or illuminate a lamp-out warning indicator, as the mis-match of current flowing troubles the CAN (controller area network) managing system.
The solution for hyper flashing is fairly easy and inexpensive, the addition of a 50W 6 ohm resistor near each LED bulb added, spliced into the wiring (the resistor’s two leads are spliced to lamp positive and ground– in parallel with the LED bulb). These are widely available online for roughly $10 per pair. This primitive work-around wastes roughly the same energy as the original bulb, in the form of heat instead of light, negating any energy savings reaped from the LEDs, but does fool the control system into thinking everything is original. It’s important to mount the resistors to a metal surface such as the inner fender to dissipate heat, as they get warm/hot and could cause damage or fail if allowed to dangle.
LED automotive lighting is a nice improvement over incandescent lighting if done well. A whiter/brighter light with improved reliability is a good thing if kept within somewhat nebulous legal parameters. The lower current consumption is a big plus on older vehicles and trailers that often have sketchy electrical connections and circuit lengths as voltage drops are reduced throughout the circuit when current is reduced. Here’s a nicely done video on installing the resistors: www.youtube.com/watch?v=WyUh1ztBH84
Coming soon! I’m working on an archive site for past columns including a sharing portal for reader tips, recommendations, column feedback, and hopefully some video tutorials to help with common tests, inspections and maintenance procedures. It’s been a long time coming and will hopefully be worth the wait.