Switchback LED problem

[Thatlowchevy]

I recently just bought a set of Switchback LEDs for the crewcab, pretty excited when they arrived because all I’ve ever used was standard halogen for the turn signals, my problem is that when they are installed the white portion doesn’t light up, only the Amber portion, I’ve tried turning them around in the socket but they only fit one way. Anybody have an idea?


My momma taught me to drink my juice from a brown paper bag

 

[someotherguy]

Add load resistors to the circuit, regardless if you have an LED flasher or hacked the flasher to cure the hyperflash. I found that when doing switchbacks in my '94 they wouldn't work right unless I added a load resistor on each side.

Richard

 

[delta_p]

^^^This
Since the internal electronics of the switchback use voltage sensing each one needs the load resistor added and they'll work

 

[someotherguy]

For what it's worth, it's been YEARS since I did this - and it seemed counterintuitive at first how I hooked up the load resistors. I was also running LED's in the corner marker and since that's also on the park light circuit, I was having problems. If I recall, the corner LED would not glow at all. If I put a regular bulb in there it would glow very dim. This was prior to the resistor install. When I got everything working was with switchbacks in both sockets, LED corner bulb, and load resistors - but the resistors installed on the park light side of the circuit instead of the turn signal side. Hope that makes sense. Normally you would put resistors on the turn signal side to cure hyperflash, but I had already taken care of that by hacking my flasher.

Richard

 

[df2x4]

Every time I see one of these threads it makes me so glad that I left all of my regular bulbs alone...

 

[delta_p]

I'm actually of the opposite. Except for the head lights, i changed all mine to LED's and like it. wishing they would've had them 20 yrs ago.

 

[df2x4]

They're definitely brighter and safer for the purpose of signal and brake lights... But man what a headache to get them all to function properly. Not to mention once you're over that hurdle, the different flasher module will never let you know via hyperflash if you've got an LED out. I like the factory setup that lets me know if most things are out without even having to get out of the trucks. Also this is more of a personal thing but I hate looking at LED light for extended periods of time, really hard on the eyes. I changed my red truck over to a 100% LED interior and later changed back to standard bulbs because I started to hate it.

Sorry for the thread derail, end of rant!

 

[delta_p]

The led's i used just plugged in and the flasher too, except for the switchbacks discussed here which needed some resistors.

Except for the under dash lighting and the dome light, I got all my led's with the same comparable wattage and/or lumen so for instance the gauge cluster used the 3 - 5 watt led 194 equivalents, not the 9-10 watt equivalents often discussed here. They're not bright. I feel ya though, but it's not that hard either.

 

[someotherguy]

I feel ya though, but it's not that hard either.

Yeah...there's degrees of difficulty depending on the vehicle.

About the only 2 issues you run into on a GMT400 are, gotta use SRCK bulbs for the brake/turn position in the taillights, and have to replace the flasher with an LED-compatible piece or simply hack your existing flasher which is literally as easy as cutting one leg off the IC inside the flasher.

Switchbacks are a whole separate issue as that's kind of above-and-beyond the usual LED conversion and can take extra work to make them function correctly. Most vehicles have just 1 signal bulb for each side and switchbacks tend to work fine in those; GMT400's having 2 bulbs up there (plus the unusual wiring of the corner bulb) seems to throw off their sensing circuitry that controls the switchback behavior.

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Dammit I miss that truck

Richard

 

[df2x4]

Dammit I miss that truck

Do you have any idea where it went after the last guy sold it?