Headlight or Turn signals

RezTech

Original poster
Member
May 23, 2020
7
86034
Have '07 4.2
Changed all external lamps to LED. Replaced flasher relay the stopped Hyper-flash. Now have an intermittent problem that flashers won't work unless I turn off auto Headlamp. This is not a consistent error... but at night I need to have my Lights on so no turn signals or lights off to have turn signals, this is intermittent the dash turn indicators will be dim if the mood strikes not to work.
Sorry kind of winded have tolerated this bug to long.
thanks for any help
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Moved from full size to 360 tech.

What relay did you replace it with? Did it do this as soon as you put in the LEDs or the relay? Have you tried going back to regular bulbs to test? I'm thinking the parking lights are back feeding or grounding into the turn signal system.

@Blckshdw, what do you think?
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
the parking lights are back feeding

This is definitely my thought as well. Same thing happened to me when I did my LED overhaul back in the day, except the problem wasn't intermittent for me. It was immediate and constant. Quick and easy test, pull out the 194 turn signal bulbs for a day or so, while you do your normal night driving. The problem should go away.

Also, do you know if the 194 LEDs you have are polarized or not? Generally most are, unless the manufacturer installed a diode bridge in the base, to allow it to function with power going to either side. Those typically cost a little more though.

Assuming yours are polarized, flipping the bulbs around would present you with a different problem. Activating the left turn signal during the day when the parking lights are off, would back feed through to the right turn signal, so it would look like your hazards are flashing. You'd see that on the dash indicators. :duh:
 

RezTech

Original poster
Member
May 23, 2020
7
86034
Sorry took a while to respond
These are the Parts that I used, got thru Amazon

Hazard Warning LED Flasher Relay for GM Turn Signal Relay Flasher Module,
Fix Hyper Flash, Replace LM487 10383321 15231201 15764135

AUXITO 194 LED Light Bulb,
Amber Yellow 168 2825 W5W T10 Wedge 24-SMD 3014 Chipsets LED Replacement Bulbs for Car Dome Map License Plate Side Marker Lights, Pack of 2

When starting the car, before putting in gear flashers, turn signals work. As I put car in gear the flasher indicator in dash illuminate. Now turn signals and emergency flashers stop working until I turn off auto headlights. This is the predominant occurrence otherwise it's intermittent.
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
The problem is, there's no dedicated ground for that socket, and the resistance in an LED bulb is too low, so current back feeds into the other signal, which causes the problem you're having.
 

Ilikemy3s

Member
Dec 3, 2011
367
The problem is, there's no dedicated ground for that socket, and the resistance in an LED bulb is too low, so current back feeds into the other signal, which causes the problem you're having.
WHat if he wires in resister in series to up the value or even a diode to limit the current to one way ?
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
The LED is already limiting the current one way, so only the parking light function works. Adding a resistor could work, but I don't know the math to determine how much is enough, but not too much.

When I ran into this problem forever ago, I ended up building a polarity changer out of a DPDT mini relay, and a number of diodes. (OEM connectors and such to make it PnP) Of course that also depends on the OP's level of comfort with soldering, and understanding of electronic components :undecided: I'd imagine something similar could be out there ready made at this point.
 

RezTech

Original poster
Member
May 23, 2020
7
86034
I have an electronics tech background, not automotive but documentation/schematics are hard to find.

Thank you for all the help and information.
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
Then this post may make sense to you :book: Since I was using switchback LEDs, I needed both functions at that socket to work, not just 1 of them.


Edit: I'm remembering how the diagram confused folks before. I had a wire going from pin 11, to pin 8, then out to the connector, as well as one from pin 6, to pin 9, and then out to the connector. Hope that makes it less muddy...
I've gotten a number of requests on how to make a polarity changer for the corner switchbacks, so here's the scoop. Someone with an Envoy will have to clarify for me, but your 194 corner bulbs don't flash do they? :undecided:

Required Parts:
2 x DPDT mini relays
6 x 12V diodes

Optional Parts:
2 x AC Delco Connectors: PT2426
2 x AC Delco Connectors: PT1324

Here's a mock up of the end result I came up with. I ran the ground connection to the fender grounds on each side. The OEM connectors are only required if you want to make this plug and play, but they are pricey. You could also cut the turn signal and parking wires, and splice the polarity switcher in.

I will say, if you go plug and play, things will be a bit more crowded around the top corner of the headlight, so don't skimp on the wiring going into/out of the relay. You'll need to have enough wire to allow the changer to be folded over and tucked away. I used 'liquid tape' to weatherproof it, but you could wrap it with electrical tape, cover it with silicone, or whatever else you've got on hand.

194SwitchbackPolarityModule.jpg


IMAG0068.jpg
 

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