Suddenly both signals blink no matter which I select

[focusinprogress]

Just a few days ago, I was told by a friend following me that both rear signals blink no matter which way I'm turning. I've looked over the diagram and I can't seem to understand how it never did this in the first place considering the way they're connected. Is this a common issue? I have no idea where to begin.

Using the switch - Left makes all four blink, right makes front right and both rear blink. I notice there's two flasher relays in my dash as well...both have been replaced with electronic flashers instead of thermal (in the past - everything has been working as it should for almost a year since I got this truck)

[focusinprogress]

Further info. Grabbed my powerprobe and did some testing on where the harness from the column plugs into the body harness.

With it plugged in, applying power to each color here's what happens (colors are to column side) I also have the rear lights unplugged from the harness at the right rear tire

Green/white = left
White/blue = right
Green = right
Red/black = right
Orange/black = right

With it unplugged (body side colors aren't identical so for sake of continuity I'm using the colors from column side)

Green/white = left
White/blue = right

The rest do nothing.

[basketcase0302]

focusinprogress » Sat Jun 25, 2016 11:36 am

Just a few days ago, I was told by a friend following me that both rear signals blink no matter which way I'm turning. I've looked over the diagram and I can't seem to understand how it never did this in the first place considering the way they're connected. Is this a common issue? I have no idea where to begin.

Using the switch - Left makes all four blink, right makes front right and both rear blink. I notice there's two flasher relays in my dash as well...both have been replaced with electronic flashers instead of thermal (in the past - everything has been working as it should for almost a year since I got this truck.

The newer electronic flashers shouldn't have anything to do with this-but they do cause the lights to flash faster usually.
This will typically be a bad turn signal switch in the steering colum-but first verify this as the switch is a pain to replace.
What year truck is this and what wiring diagram are you using?

[ThinLizzy13]

To begin with check all your grounds. I had this happen in my 66. I cleaned all sockets, replaced all the bulbs, checked all chassis grounds, and tore apart my column and replaced the signal switch and cleaned up all the little metal parts that moved inside; still nothing!

I ended up accidentally bumping the hazard switch on my dash, and the issue was fixed! I missed a ground. My switch wasn't tightened to the metal dash and properly grounded.

Bad grounds will make weird things happen.