Strange turn signal behavior.

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cheavyk10

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Hey guys, first post here, greetings from Washington State.
I recently acquired an 04 Tahoe, and have been enjoying it.
The issue I'm having lately is the left turn signal hyper flash, but when I checked for a blown bulb, the front and rear bulbs were not flashing on the driver side, but the mirror signal was working, although fast. Running lights/ headlights working no problem.
I swapped out the turn bulbs front and rear, with no change. I went for a drive and it started working normally all of a sudden, but then it went back to not working.
So I'm thinking it may be a ground issue, or possibly the flasher? When I used the hazards same thing no lighting up of the left bulbs.
The previous owner had put LEDs in the indicator lights on the side of the housing, I was thinking of going back to the normal bulbs.
Let me know what you think thanks!!
 

MassHoe04

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For anyone with a Tech 2...

Here is the menu path for front turn signal:
Body > Body Control Module > Special Functions > Output Control > Light Test

Ground connections are on the LF and LR body mounts. Wouldn't hurt to check. Clean and tighten, then spray some paint or primer over the top after bolted back on.
Just to rule those grounds out of the equation...
 

MassHoe04

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The fact that both front and rear bulbs are lighting, but the mirror (and dash indicator lamps, did you say too?) are hyper-flashing might indicate a damaged wire or ground somewhere. Bad bulb or socket would go out on one corner and hyper-flash the dash indicator on that side, but the other turn signal bulb sand mirror should still light up.

Was there any tinkering under the dash or in the steering column recently before this started?
Wondering if wires in the steering column or in/out of the body control module got damaged in the process of other work that might have been going on.
 
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cheavyk10

cheavyk10

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Ok, I reread my original post and realized it's a bit confusing.
When the left turn signal is engaged, the indicator lamp on the dashboard flashes fast, and the mirror signal lights up and flashes the same, but the front and rear left turn bulbs do not light up at all.
The running lights work no problem.
I've owned this truck since August and haven't tinkered with anything behind the dash. I did change a washer pump so maybe I messed up the ground wires there without knowing it.
 

MassHoe04

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Thinking on the most basic level, which sometimes is required for me to function...

Turn signal bulb needs ground to light up. If both front and rear on that same side are not lighting at the same time, I would look to see what connection they have on common.

A damaged ground wire grounding in the middle, instead of at the end with a connector, should still work.

So looking at hot wires carrying 12V to the bulbs when the turn signal relay tells them to light up... What link in the wiring do the front and rear turn signals have in common?
That is what I would be trying to figure out.

@rockola1971 and many others here are super at electrical. This should be pretty easy for someone to help you figure out.
 

rockola1971

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Only thing I could find common to the left front and rear turn signals is their power feed between fuse block connection a terminal F3 of the Instrument Panel fuse block and the Fuse Block under hood terminal F3. Sounds like one of those 2 points is corroded or broken wire occassionally making contact when stuff works. Flash module is common to both turn signals and the one on mirror so if the module were bad then none of them would work at all. When the indicator on the dash flashes along with any working on that particular side also flashing that means there is atleast one bulb electrically open (AKA Burnt out) OR a wire leading to one or more is broken OR a terminal along the path is corroded OR the bulb socket itself is corroded. All of these would be an electrical open.
What I would do....when the problem arises, goto terminal F3 of underhood fuse block and see if 12v is there on and off. Probably wont be since on the other side of the fuseblock terminal E1 is where both left front and rear turn signals are fed from and Y is there. Then work your way back and see where it is and isnt. My bet you will have to pull the fuse blocks and you will find corrosion, especially the one under the hood. Not uncommon.
 

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corvette744

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Basic first step put a test light on the socket of front or rear bulb when turn signal is on and not working.Do you have power -Do you have ground should take 30 seconds to test.IF not let us know.If not trace pwr or ground back form there rockola1971 was nice enough to print you the exact pic you need to trace it.
 
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