Parking light/side marker issue LED bulbs

[bozly]

I have a 1971 c10 and when my parking lights and side markers are standard incandescent bulbs everything works normal. However, when I replace my parking light bulbs with the equivalent LED bulbs my side markers no longer illuminate and my turn signals are illuminated solid on my dash. Is there a quick fix to this? I'm guessing the LED bulbs don't offer enough resistance and the truck thinks a bulb is burnt out or missing.

[Getter-Done]

This video below should help you.

Some of the LED bulb types need to use different flasher.

Other (My Nephews Furd) wiring systems I have had to install thesein the link below.
Link. https://www.superbrightleds.com/led-...ping%20Adgroup

1967-72 Chevy C10 LED Turn Signal not working fix...

[Richard]

Originally Posted by bozly

I have a 1971 c10 and when my parking lights and side markers are standard incandescent bulbs everything works normal. However, when I replace my parking light bulbs with the equivalent LED bulbs my side markers no longer illuminate and my turn signals are illuminated solid on my dash. Is there a quick fix to this? I'm guessing the LED bulbs don't offer enough resistance and the truck thinks a bulb is burnt out or missing.

On 71-72 trucks the front sidemarkers ground through the front turn bulb element so the sidemarker can flash. An led acts like a diode and only allows electricty to flow one way. So when an led is used in the front turn location the sidemarker has no path to ground. You could directly ground the led sidemarker and loose the flashing capability like the 69-70, or install relays.

[VetteVet]

Here is a diagram showing the wiring of the marker and turn signal lights.

[Richard]

The previous diagram posted by VetteVet is for 69-70

Here is the one for 71-72

[VetteVet]

Thanks Richard I didn't look close enough before I posted.

[Richard]

Having both diagrams is a good thing.
I did a crude drawing of installing a Bosch 12v relay in the system. Apologize for my bad paint skills. Doing this should allow led's in both turn and marker locations and keep the marker alternate flashing with front turn. A relay would be needed on each marker.

[SeventyOne]

What about adding diodes and a resistor like this? (stolen screen shot from a jeep website)

[Richard]

Originally Posted by SeventyOne

What about adding diodes and a resistor like this? (stolen screen shot from a jeep website)

Attachment 2347751

Not an electrical engineer. FWIU the diodes will do nothing. The led acts like a diode and prevents sidemarker from getting a ground. Try it and see if it works? At best the resistor will limit current flow and dim the bulb..

[SeventyOne]

Originally Posted by Richard

Not an electrical engineer. FWIU the diodes will do nothing. The led acts like a diode and prevents sidemarker from getting a ground. Try it and see if it works? At best the resistor will limit current flow and dim the bulb..

The diodes will certainly stop the backflow of current between DLR/Signal. I think what you're missing is the ground wire completing the circuit off the LED which will allow both the DLR and Signal to flow at the same time.

So the LED would receive (resisted) power via the DLR and go to ground. Then when the turn signal is applied the LED receives full power via the other wire and blinks due to the flasher.

The above drawing/schematic was borrowed from a Jeep website dealing with the same OEM floating ground setup - so i know it works . Just offering another/simpler solution.

[Richard]

Originally Posted by SeventyOne

The diodes will certainly stop the backflow of current between DLR/Signal. I think what you're missing is the ground wire completing the circuit off the LED which will allow both the DLR and Signal to flow at the same time.

So the LED would receive (resisted) power via the DLR and go to ground. Then when the turn signal is applied the LED receives full power via the other wire and blinks due to the flasher.

The above drawing/schematic was borrowed from a Jeep website dealing with the same OEM floating ground setup - so i know it works . Just offering another/simpler solution.

Sorry I just do not get it? I do know with an led in the front turn location on a 71-72 truck the sidemarkers will not light because the ground from the sidemarker goes through the bulb, just like your illustration. Do not understand how the diodes and resistor correct the path to ground for the sidemarker. Looks like it is still through the bulb.
The wire from the marker in the chevy is the ground from the marker, not a hot. Maybe the jeep configuration is different.

Edit: Not saying it does not work- I just want to understand why adding the resistor and diode makes it work. Load from marker circuit sees the resistor and reduces amperage through the led so it can ground? If I understand I can apply knowledge elsewhere. Kind of how I learn, even now at the age I am.

[SeventyOne]

Originally Posted by Richard

Sorry I just do not get it? I do know with an led in the front turn location on a 71-72 truck the sidemarkers will not light because the ground from the sidemarker goes through the bulb, just like your illustration. Do not understand how the diodes and resistor correct the path to ground for the sidemarker. Looks like it is still through the bulb.
The wire from the marker in the chevy is the ground from the marker, not a hot. Maybe the jeep configuration is different.

Edit: Not saying it does not work- I just want to understand why adding the resistor and diode makes it work. Load from marker circuit sees the resistor and reduces amperage through the led so it can ground? If I understand I can apply knowledge elsewhere. Kind of how I learn, even now at the age I am.

All good - take another look at the drawing I posted, specifically the top drawing. Note there's two power wires going to the stock bulb (DLR + Signal) - this is the OEM setup. Then notice the "cut here" instructions.

Then the bottom drawing has both the power wires merging (after the diodes/resistor) and going trough 1 of those cut wires to the bulb. The other wire coming off the bulb then becomes a ground wire - you need to ground it to the chassis.

So you need to cut your stock harness, alter how the power wires flow power and add a ground. Alternatively, because i don't want to cut my harness/wires, I will use 194 male/female bulb sockets to create a plug and play jumper wire like the image below.