Just like the front side marker lights do, they also flash with the turn signal. I want the rear side markers to do the same. Does anyone know how to do this? (91 bird)

 

Side markers typically have a brown power wire for park/tail and a black ground wire. But the front side markers don't have a black ground wire; they have two power wires: the brown park/tail wire, and the side-appropriate light/dark blue turn signal wire.

When the park/tail lights are ON, and the turn signals are activated, power is applied through both wires at the same time, steadily through the brown wire, pulsing through the blue wire. The applied turn signal power causes a cancelation/"short"/grounding out of all power to the light during the pulse period, so the light goes dark. And because the lights go dark DURING the power pulse, the side markers "flash" OPPOSITE the turn signal "flash": OFF with the pulse, ON with no pulse, while the turn signals are ON with the pulse, OFF with no pulse.

When the park/tail lights are OFF(think daytime), and the turn signals are activated, there's no power from the brown wire, only power pulsing through the blue wire, so the blue wire, alone, powers the light, without cancellation against the brown wire, so the side markers "flash" on/off, pulsing WITH the turn signal "flash."

Probably isn't considered necessary for the rear side markers to flash. How often does someone back-up, "leading" with the rear of the car, while signaling a turn? But if someone wanted to try this with the rear side markers, then he could cut the black wire going to the side marker, tap into the yellow or light green turn signal wire, connect it to the black wire going into the side marker and see what happens.

 

Doesn't work it's keeping the rear turn signals on or backfeeding

 

Doesn't work it's keeping the rear turn signals on or backfeeding. And it works out real well when making lane changes especially on the freeway bud

 

"According to Hoyle," that's exactly what should've happened. The only reason it works at all, is because a tiny wattage bulb isn't strong enough to affect the normal signal lights, but adding more of them to the circuit, can be. And now we know, one more is too much. So "Hoyle" was right, and that's why GM didn't do it. Good test, though.

 

Interesting! I am actually using all LED.
BUT, did have the tiny 194 style bulbs in the front markers when I tested. Let me try with all 4 markers with LED....

It seems to not work at all when using the brown wire n the rear. I had to use the front parking light wire in order to achieve what the front signals & markers do: alternate blinking.

 

With all sockets using non-polarity LED:

Parking lights on & right turn signal = only rear marker & rear turn signal alternating normally.
Front marker + signal NOT flashing. No noticeable back feeding.

Parking lights on & left turn signal = same as above.

Parking lights off & right turn signal = front and rear alternating normally with no noticeable back feeding, but it's there if you look hard.

Parking lights off & left turn signal = front and rear alternating normally WITH some back feeding current of about 25% into all bulbs including instrument cluster. Entire cluster is LED.

How I have it wired:
1 wire run from right front parking light/turn signal/marker blue lead to right rear marker lead, where black lead ground wire, which is now disconnected.

The other side is 1 wire run from light blue wire that is coming from the turn signal switch under the steering wheel at the harness to the left rear marker black lead ground wire, which is now disconnected.

​​​​​​When I tried this using the rear turn signals it didn't work because the rear turn signals do not illuminate, of coarse. That's why I'm hooked into the front. unless anyone has a better way that may work?👍

I wonder why only one side was backfeeding? It didn't change anything when I put glass filament 194 bulbs into the front side markers, either. Is it due the way I have it wired?
Using electronic flasher, btw.

If anyone knows how I can pull this off without anymore extra parts, please share.

If I can avoid buying relays and resistors, that'd be cool. But everything I've read in other forums their using extra parts.

​​

 

So you added a rear turn signal feed to the cut black wire, then tapped the front side marker's brown park/tail wire and sent it to the rear side marker's brown park/tail wire, to make the rear marker flash? Ok, that would work, because you'd be providing two exclusive power feeds, and you'd be grounded through the front turn signals. I'm guessing incandescent did work after all, or did you use/try LED?

91 'bird, you say? So the front turn signals each have two exclusive power feeds, park and turn, because they double as parking lights and turn signals, their own ground, too, and the front side markers share those two feeds and ground. But the rear turn signals do NOT have two exclusive power feeds, just one for turn; the lights don't double as parking lights, so they don't have a brown park/tail wire, and that's why this can't work with the rear side markers. But when you fed an exclusive brown park/tail to the rear marker, it worked like the front marker... and because that lead also provided the path to ground.

Initially, though, by cutting the side marker's ground wire and adding turn signal power there, that power was traveling out through the brown wire to all of the brake/tail lights, making them all light up. Yup, that would do it LOL. And since they all were lighting up, they were obviously grounded, so where the ground is coming from might not matter.

So both, a rear turn signal feed and a rear park/tail feed have to be running exclusively through your rear turn signal, like the front turn signal/parking light, for this to work on the rear side markers, and both don't, so it didn't/can't work. The only way to make it work, without completely rewiring your rear harness, which is doable, but probably not worth it, is to do exactly what you did. Although, rewiring the harness might make for an interesting little "Social Distancing" project, if you have too much time on your hands, like so many people do!

Looks like we were writing at the same time, so I haven't read yours yet. Doing it now.

 

LOL, ok, no, not by doing exactly what you did. It looks like you've mixed your front turn signals, front side markers and rear side markers, all with your tail lights.

I thought you'd tapped the brown leads from the front markers and ran them back to the rear markers' brown wires(now cut from the rear harness), with rear turn signal leads to the black wires(originally cut from the rear harness). But you tapped the front blue leads and ran them back to the black wires, and the brown lead from your rear side markers is still open to your tail lights. If you want to do it that way, then I think you should cut the brown wires free of the rear harness, then tap the brown wires from the front markers and run them to the back markers, like you did with the front's blue wires, powering the rear side markers AND the front side markers, all through the front turn signals/parking lights/ground. That might be too much power for the front to cope with, though. But however you do it, seems the rear side markers must some how be free of the tail lights, getting their tail power through a separate source, to run strictly with the turn signals(preferably rear), like the front side markers do with the front turn signals.

To try to detail it more keeps getting more and more complicated to write and really, really long LOL, and it's really freaking late! This can be done, but I doubt it's worth all the trouble. So as Joshua, the "War Games" computer said after running a full simulation of "Global Thermal Nuclear War," or WWIII, "strange game, seems the only winning move is not to play." Or as the Robot in the episode of "Lost in Space" that I'm watching right now just said, "warning, on collision course with ridiculous radiation!" In other words, probably best to put everything back the way it was. Like I said, it's late LOL.