Strange turn signal light gremlin

[mtnmankev]

On my 84 K10, I turn on park lights, and all four corners of the truck light as they should.
Turn park lights off, turn the key to ON position, and flip the turn signal lever for right turn, both the right front turn bulb flashes and the corner marker light flashes with it.
Turn park lights on, key on, right turn position, the RF bulb flashes and the corner marker bulb goes out as the turn bulb flashes.
Go for left turn, I have to jiggle the turn signal switch lever a little, and get a solid glow from the dash indicator bulb, but no bulbs light up front or rear, and no left rear brake light.
I tried different flashers, get the same result.
I did have a problem for a couple years where the ground tab from the LF bulb socket had disappeared, and all the time the lights were on I had a solid glow from the left turn dash indicator bulb. I wonder if that damaged my turn signal switch ......
And how did the corner marker light bulb get involved with the turn signal ? It should be a separate circuit.

 

[chengny]

I did have a problem for a couple years where the ground tab from the LF bulb socket had disappeared, and all the time the lights were on I had a solid glow from the left turn dash indicator bulb. I wonder if that damaged my turn signal switch ......

I doubt that your turn signal switch was damaged. But it sounds like you do have another grounding issue. Recheck the ground points on both sides of the radiator support frame.

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Pull the bolts, clean the harness connector tabs on all the wire ends, clean the bolt threads and internal frame threads, clean the connector landing area on the frame and reassemble.

And how did the corner marker light bulb get involved with the turn signal ? It should be a separate circuit


The parking light lamp and side marker lamp are on the same circuit and kind of play off each other. When no directionals are in use, they are both lit. But when the directionals are activated the two lamps flash opposite each other. It is a neat trick and is explained in the images below:

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[mtnmankev]

Thank you so much for explaining that. I was worried I had a serious electrical issue going on.
I found one ground that needed attention, from the RH side of the core support to the frame, it was rusted at the frame, so it got cleaned up. Still no left turn or brake light.
I removed the LR park/turn bulb, checked the wires and ground. Test light showed solid continuity to the socket (but even though the test light completed the circuit, it would not flash). Despite the fact the bulb seemed good, I put another one in for grins and giggles, and 'voila, I had working lights.
At this point I am starting to suspect the space aliens are messing with me again. I have true stories that happen here, but I'm not sure we have a place on the forum to share them.

 

[chengny]

At this point I am starting to suspect the space aliens are messing with me again. I have true stories that happen here, but I'm not sure we have a place on the forum to share them.

Oh man, don't worry about that, there's a place for everything here. Head on over to "The Lounge".

http://www.gmsquarebody.com/forum/forumdisplay.php?f=21

It's not the kind of lounge where folks go to get drunk, but some of the threads make it seem like it is.