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Blinkers acting weird?.?.? 86 K5 Blazer

dconway32

dconway32

ShakyJedi
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Hey guys,

So I've noticed my blinkers are acting weird. When I'm driving around during the day with the headlights off they work at the normal "blinking" speed. But when i have the headlights or even just the running lights turned on, when I click the knob down or up for a left or right turn, the indicator light comes on but it doesn't blink. I tested this out in my driveway by checking to see if the lights are actually blinking and maybe it's just the indicator light on my gauge panel, but the lights on the front and back of truck don't blink either.

This is a new truck to me and I'm still trying to figure out the querks and stuff.

But before I start taking stuff off to figure it out, I wanted to ask the forum and see if anyone has any suggestions.
 
diesel4me said:
My first guess is one of the bulbs has the filament for the parking light broken and touching the other filament for the brake light..

Second guess is a poor ground..
Click to expand...
Ok thanks for the reply! I'll check those out. I'm thinking poor ground somewhere too.
 
I would look at the ground connections first. The bulb to socket, wire harness at the radiator support. Look on the engine side of the radiator support for a bolt with ground terminals. There is one on each side of the radiator. I would just pull each bolt out, clean to bare metal at the bolt hole and terminals. Then I use some grease or anti-corrosion compound as I reassemble it.
If it works with the lights off, it should work with them on if you find the problem (or problems).
You may want to check that no one has installed a LED in the side marker as this doesn't work with factory wiring. The side markers on the front fenders don't have a ground wire to the chassis. They are tied to the marker light AND turn signal circuits. I don't know if this could be your problem, but checking it is easy.
 
Ford had this problem a lot in the 70's if its what I think it is. When you turn on the headlights the blinker indicator lights on the dash glow faintly or light up fairly bright.
Drove me crazy on my '76 Torino.
Finally discovered that the ground wire in the front light sockets had a bad crimp onto the wire inside the socket. It would run hot when the marker lights were on, and cause the ground contact to corrode where it touched the side of the bulb.
The bulb has two filaments. One is hooked to the wire from the flasher, and the other is hooked to the marker light wire. But they are both hooked to the same ground internally.
When you turn on the marker light normally, the power goes in the marker wire contact and out the ground. If that ground is bad, then it will go through the marker filament, then into the shared ground connection with the blinker filament, into the blinker circuit and go to ground through the indicator bulbs.
I doubt the socket internal ground is bad, probably the socket ground wire where it hooks to the frame ground.
 
Behind the rear lights there are grounds that are often corroded or loose. Also look for any funky wire connections someone may have done for trailer light connectors.

I have found huge rat nests of bad wiring hidden up under the rear bumper before...
 
Interested to see how this comes out. My 81 just started doing the same thing.
 
One of the rear light grounds just randomly decided to give up on me at one point, definitely a thing. Not a broken wire or anything, the ground wire just stopped making contact.

I've also had a screwed up bulb socket at the rear which caused random issues.

Always easy to pop the lenses off both rear lights to check bulb function, swap them side to side, one at a time.
 
Thanks for the input guys . I haven't had a chance to work on this yet but will definitely let you know more once I get into it. Planning on checking everything you are talking about. Trying to get to it this week.
 
So had a chance to work on this. After checking wire connections and determining that they seem to be good, I checked my Dakota Digital dash settings. I changed the signal indicator from "Gauge" (means that the digital signals on the gauge will flash) to "OEM" (means the OEM turn signals will flash). This seems to have fixed the problem. However, after driving around yesterday some more. it started doing it again, but only every so often. not every time like before. Seems to be hanging up on the left turn signal more frequently than the right one. After thinking I had it figured out, i'm stuck again. I haven't messed with taking the wheel off to get to the signal switch yet. but wanted to ask you guys before I take that step for anything you might suggest.


Blazer Dash - turn signals.jpg
 
shady said:
Interested to see how this comes out. My 81 just started doing the same thing.
Click to expand...

Same here, noticed Saturday mine started it, but only on the LH drivers side blinker. Odd that it’s isolated to one side?!?

haven’t had a chance to check grounds yet.
 
Hmm.. really weird. Glad i posted about it. Sounds like there are a few of us having this issue. I'll be trying to find some time this week to work on it some more.... I'll post what I find out.
 
70jimmy said:
I would start with the flasher units if they are still stock set up, cheap and easy to replace.
Click to expand...

That's a good thought. I haven't looked at that. I'll check it and report back when i can.
 
bigjimmy82 said:
Same here, noticed Saturday mine started it, but only on the LH drivers side blinker. Odd that it’s isolated to one side?!? haven’t had a chance to check grounds yet.
Click to expand...

Solved! Got time to trouble shoot this afternoon. Drivers side rear taillight had broken yellow wire, so that side didn’t have brake lights either :whistle:. Root cause was previous owners trailer light wiring with those damn blue wire taps. So all those are gone and new heat shrinked butt connectors. All back to normal!
 
bigjimmy82 said:
Solved! Got time to trouble shoot this afternoon. Drivers side rear taillight had broken yellow wire, so that side didn’t have brake lights either :whistle:. Root cause was previous owners trailer light wiring with those damn blue wire taps. So all those are gone and new heat shrinked butt connectors. All back to normal!
Click to expand...

Nice! glad to hear you got yours fixed. unfortunately, all my lights are working so mine is a different problem. I'm going to be working my signal issue along with fixing my tailgate window motor stuff and watching the NFL draft tonight in my garage. All the parts I ordered are now in so hoping to get this figured out tonight.

I'll report back on how it goes.
 
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