Blinkers are acting up

[1984 Chevy k20]

So my 84 k20, a while ago I had to change some bulbs behind the gauge cluster cause some burned out, got done with that and after I did that, now what happens is,

Running lights/ head lights off: blinkers all work fine

Running lights/ headlights on : front marker stays lit but doesn’t blink, fender blinker and rear tail light blinker alternate

I do not know what’s going on or where even to start, if anyone knows what’s going on and how to fix it, that would be amazing and thank you so much

 

[Jgonick]

Did you change any turn signal bulbs?
If dealing with incandescent bulbs. Check the front turn signal bulbs are correct and not bad They are dual filament bulbs (probably 2057) Also make sure you have the correct bulb in the side marker lamps. (probably 194) Do not use LEDs specifically in these locations -they will cause problems unless modifications are made. LEDs (light emitting diodes) -diodes only allow current to flow in one direction-the side markers actually gets current from different directions depending if lights are on or not. As of now- I don't think the gauge cluster is involved.

This is generally one of the main causes of odd turn signal issues-

 

[1984 Chevy k20]

Did you change any turn signal bulbs?
If dealing with incandescent bulbs. Check the front turn signal bulbs are correct and not bad They are dual filament bulbs (probably 2057) Also make sure you have the correct bulb in the side marker lamps. (probably 194) Do not use LEDs specifically in these locations -they will cause problems unless modifications are made. LEDs (light emitting diodes) -diodes only allow current to flow in one direction-the side markers actually gets current from different directions depending if lights are on or not. As of now- I don't think the gauge cluster is involved.

This is generally one of the main causes of odd turn signal issues-

I didn’t touch any of the bulbs involving any exterior bulbs but I will double check see if any are burnt, it could have been odd coincidence

 

[fast 99]

Running lights/ headlights on : front marker stays lit but doesn’t blink, fender blinker and rear tail light blinker alternate

alternate? one side goes out and the other side lights? Sounds like a ground issue.

Another problem that will absolutely drive a person nuts is a broken filament inside a bulb that drops down on the other filament.

 

[1984 Chevy k20]

alternate? one side goes out and the other side lights? Sounds like a ground issue.

Another problem that will absolutely drive a person nuts is a broken filament inside a bulb that drops down on the other filament.

Ya kinda like that, like how in normal operation the front marker and side marker when the lights are on and you turn your blinker should alternate, but as stated is the wrong lights alternating

And when I get a chance next I’ll look into the grounds and filaments if need be to see if maybe something in that area is causing issues

 

[Jgonick]

Another problem that will absolutely drive a person nuts is a broken filament inside a bulb that drops down on the other filament

Exactly- will do very odd things.

Attachments on this post Link shows how the front turn signals & side markers work- if you are interested

 

[Jgonick]

The dual filament bulbs - found in front turn signals & brake lights -is one of the first things l look at when running lights affect turn signals. That is the place where the two circuits easily come into contact.

 

[1984 Chevy k20]

The dual filament bulbs - found in front turn signals & brake lights -is one of the first things l look at when running lights affect turn signals. That is the place where the two circuits easily come into contact.

I’ve never even pulled the back brake light housings off and checked the bulbs, and as far as I can tell by the condition of the truck, it’s got really low original miles, so it quite possibly could be in there

 

[YakkoWarner]

I’ve never even pulled the back brake light housings off and checked the bulbs, and as far as I can tell by the condition of the truck, it’s got really low original miles, so it quite possibly could be in there

I'm with Fast99 on this one - that sounds like a grounding issue to me as well. The sockets and housing on trucks of this age have corrosion - how much depends on a lot of factors but none of them (unless already restored) are rust free - so thats where I would start. I frequently add grounding wires to sockets to deal with this kind of thing because the body grounds through the fastners become unreliable with age. Its even more pronouced on British cars, but adding grounds to the sockets works even there.