LED Turn Signals/Parking Lamp Issues

Vehicle: 1994 GMC Jimmy.

Background: I work at a fabrication shop where we make custom bumpers, rock sliders, cages, and the likes. Often, custom lighting is installed to replace lost functionality of lights that were originally in bumpers or grills. These replacements are typically LED.

Work done: Custom front bumper made for this Jimmy and we placed 3/4" LED lights for use as running lights/turn signal indicators. The original turn signal bulbs were dual filament, 3 wire lights. We've replaced them with a 2 wire amber LED. We replaced the factory flasher relay with an electronic relay.

Issue: When there are incandescent bulbs in the parking lamps, the led turn signals work (though don't light as parking/running lights). When we place LED bulbs in the parking lamps, nothing works except for those parking lamps. I was told that the polarity gets reversed when you use the turn signals and the lights are on. Is this correct? Is there a way to account for that and still use LED bulbs?

https://www.bbbind.com/free-tsb (bookmark)

https://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=42672

In theory, this will work, but you'll need one for each side:



You'll also need to play around with different capacitor values, too. It may need to be "ginourmous" (aka over 1000 uF). I'd recommend getting an assortment rated at 16 volts or higher. If they are polarized be sure to observe proper polarity. Often there's an arrow with a minus sign (-) pointing to the cathode (negative lead).

Other options would be rewiring the turn signals, or installing additional separate lamps.

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My ex once told me I have a perfect face for radio.