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Old 05-17-2014, 08:07 PM   #1
HeloCrewChief
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Turn Signal Issues and I'm frustrated.

Hey guys. My 79 Chevy is driving me nuts. Only the left rear blinker works. When I flip the turn signal lever to the left I can hear it clicking but, when I flip it to the right I get nothing. When I turn on the lights all the lights work. I checked all the bulbs front and rear. Replaced the flashers. Sockets are nice and snug. What am I missing here.
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Old 05-17-2014, 08:29 PM   #2
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Re: Turn Signal Issues and I'm frustrated.

It could be a failed turn signal switch.

You can unplug it at the long flat "harmonica" connector on the steering column under the dash for testing without having to tear the column apart.

With the switch unplugged, you can use an ohmmeter to test for continuity between the various wires of the switch. In the "left turn" position, there should be continuity between the purple wire and the light blue wire. As well as continuity between the purple wire and the yellow wire. Similarly, in the "right turn" position there should be continuity between the purple, dark blue, and dark green wires.

Also with the switch unplugged, you can temporarily install jumper wires on the truck half of the wiring connector to simulate the functions of the switch. That'll let you know if the problem is in the switch or somewhere else. Jumpering the purple wire to both the light blue & yellow wires should make the left turn signals flash. Similarly, jumpering the purple wire to both the dark blue & dark green wires should make the right turn signals flash.
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Old 05-18-2014, 01:30 AM   #3
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Re: Turn Signal Issues and I'm frustrated.

Try your four way flashers. See if they work. Then you know if it might be a bulb?

Then I would be checking all the grounds. Maybe put in extra grounds like box to frame, cab to frame, engine to frame, etc. they corrode and lead to all kinds of strange goings on electrically speaking
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Old 05-18-2014, 03:07 AM   #4
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Re: Turn Signal Issues and I'm frustrated.

Mine did the same. Needed a turn signal switch.
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Old 05-20-2014, 05:43 AM   #5
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Re: Turn Signal Issues and I'm frustrated.

4 way flashers do not work. Does anyone have a write up on the switch replacement. Just like to know what I'm getting into and any tips/tricks before diving in. I've done one a while back on a Chevelle with ignition in the dash. Never done one on something this new. I tried a search on the forum but, didn't really find a good write up.
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Old 05-20-2014, 06:46 AM   #6
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Re: Turn Signal Issues and I'm frustrated.

Quote:
Originally Posted by HeloCrewChief View Post
Hey guys. My 79 Chevy is driving me nuts. Only the left rear blinker works. When I flip the turn signal lever to the left I can hear it clicking but, when I flip it to the right I get nothing. When I turn on the lights all the lights work. I checked all the bulbs front and rear. Replaced the flashers. Sockets are nice and snug. What am I missing here.
Sigh..these f &)&& trucks do my head in.My turn signal stick recently broke I use my hand now to make turns hopefully people see me.
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Old 05-22-2014, 04:30 PM   #7
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Re: Turn Signal Issues and I'm frustrated.

Just replaced the turn signal switch. It was a pretty straight forward process. Unfortunately now I have nothing. No signals left or right. I'm positive I installed everything correctly. What am I missing here. Maybe a blown fuse during the process? I had the battery disconnected.
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Old 05-22-2014, 06:31 PM   #8
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Re: Turn Signal Issues and I'm frustrated.

I have continuity testing the wires ray_mcavoy said to check.
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Old 05-23-2014, 06:29 PM   #9
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Re: Turn Signal Issues and I'm frustrated.

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Originally Posted by HeloCrewChief View Post
Just replaced the turn signal switch. It was a pretty straight forward process. Unfortunately now I have nothing. No signals left or right. I'm positive I installed everything correctly. What am I missing here. Maybe a blown fuse during the process? I had the battery disconnected.
The turn signals are powered through the "TURN B/U" fuse that's located off to the left side of the fuse box, 3rd row up from the bottom. You can use a test light or voltmeter to probe the test points on both sides of the fuse to make sure power is reaching the fuse and that the fuse is good. Note that the "TURN B/U" fuse will only be live with the ignition switched on.

If the fuse checks out okay, use the test light to check for power on the purple wire at the turn signal switch connector. Again, that should have power with the ignition switched on. That point in the circuit is after the flasher so depending on how much load your test light places on the circuit, it might be lit steady or it might blink when connected to the purple wire. Either one is fine. However, if you don't have power on the purple wire then there is something wrong with the flasher or wiring.

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I have continuity testing the wires ray_mcavoy said to check.
The continuity tests I described check the turn signal switch itself. I assume you mean the switch tested okay?
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Old 05-23-2014, 07:36 PM   #10
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Re: Turn Signal Issues and I'm frustrated.

Yes, I did the continuity testing on the switch itself and it came back ok. I took a picture of my fuse block. Most of the lettering is worn off and I do not see the fuse you're talking about.
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Old 05-23-2014, 07:56 PM   #11
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Re: Turn Signal Issues and I'm frustrated.

Yeah, they can be hard to read when the lettering gets worn off. And those factory accessory wire plug-ins can make it hard to count the rows.

I believe this is the fuse ... I circled it on your pic:
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Old 05-23-2014, 08:53 PM   #12
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Re: Turn Signal Issues and I'm frustrated.

ray_mcavoy, thank you for keeping me motivated on this. I'm happy to report that I pulled that fuse to see if it was blown. It was not but, I swapped it out with another one anyway and bam! All four signals are working like a champ. I've owned several muscle cars and three 69-72's. This is my first square body but, I will say I've always had the weirdest gremlins with old GM trucks. Chevelles, Novas, Camaros are pretty straight forward but, these old trucks just need constant tinkering which is fine by me. They don't require a ton of money, I think they just enjoy your time spent with them. I hope someone searching the forum in the future finds this thread and it helps keep them motivated as I was about to just start using hand signals!
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Last edited by HeloCrewChief; 05-23-2014 at 08:53 PM. Reason: update
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Old 05-23-2014, 10:05 PM   #13
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Re: Turn Signal Issues and I'm frustrated.

That fuse has probably been in there 35 years. Could just have been oxidation on the fuse blades and/or the socket wipers. One thing you might do now that you have been into it and know how to contort yourself to get at it: pull out every fuse one at a time and then push it back in. You already know that the environmental conditions etc that the truck went through gave you bad contact on a good fuse, so why wait for the next gremlin? Head that bunch off at the pass!

And thanks for the follow-up. We all learn more every day, which makes it easier to help the next guy who has one he can't figure out.
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Old 05-23-2014, 10:32 PM   #14
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Re: Turn Signal Issues and I'm frustrated.

Quote:
Originally Posted by HeloCrewChief View Post
ray_mcavoy, thank you for keeping me motivated on this. I'm happy to report that I pulled that fuse to see if it was blown. It was not but, I swapped it out with another one anyway and bam! All four signals are working like a champ.
You're welcome! I'm glad to hear that part turned out to be an easy fix! I agree with Rich ... the problem with the fuse was likely due to oxidation & removing/replacing it was enough to re-establish contact.

Quote:
Originally Posted by HeloCrewChief View Post
This is my first square body but, I will say I've always had the weirdest gremlins with old GM trucks. Chevelles, Novas, Camaros are pretty straight forward but, these old trucks just need constant tinkering which is fine by me.
I guess some of that could possibly be attributed to the fact that trucks are often used in harsher conditions (rough roads, off-road, and such) ... more so than most cars. So parts can potentially be exposed to more dust, dirt, water, etc.

Reading back through this thread, it sure sounds like you had a weird combination of gremlins with this case ... The old turn signal switch was most likely causing the behavior you were seeing at first with only left rear signal working. But to have the fuse problem right after replacing the switch (causing all of the turn signals to quit working) was definitely a strange coincidence
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Old 05-23-2014, 11:49 PM   #15
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Re: Turn Signal Issues and I'm frustrated.

Thank you guys. Yeah, the other thing is trucks of this vintage have most likely never been restored, just "used". In any case I serviced/replaced things that need to be looked at after 35 years. FWIW the truck is in Washington state and is exposed to rain frequently which probably led to some electrical gremlins.
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Old 05-23-2014, 11:55 PM   #16
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Re: Turn Signal Issues and I'm frustrated.

Here are a few pictures of her all lit up. Keeping all those lights working on this old beast is a job in and of itself.
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Old 06-08-2014, 03:06 AM   #17
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Re: Turn Signal Issues and I'm frustrated.

I've had some issues with my '80 K20 since I've been starting to put it back together. I really suck at wiring and figuring out the issues but, I purchased a GM Service Manual off of Ebay. It's been a great tool and resource for me during my whole project. I think they are 10x the manual that Chilton's manuals are. He's a link check them out.

http://www.ebay.com/itm/1979-Chevrol...2403c0&vxp=mtr
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Old 06-09-2014, 11:29 AM   #18
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Re: Turn Signal Issues and I'm frustrated.

Quote:
Originally Posted by Eug396 View Post
I've had some issues with my '80 K20 since I've been starting to put it back together. I really suck at wiring and figuring out the issues but, I purchased a GM Service Manual off of Ebay. It's been a great tool and resource for me during my whole project. I think they are 10x the manual that Chilton's manuals are. He's a link check them out.

http://www.ebay.com/itm/1979-Chevrol...2403c0&vxp=mtr
Way better manuals and usually not too spendy on fleabay.
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Old 06-09-2014, 11:36 AM   #19
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Re: Turn Signal Issues and I'm frustrated.

Quote:
Originally Posted by HeloCrewChief View Post
ray_mcavoy, thank you for keeping me motivated on this. I'm happy to report that I pulled that fuse to see if it was blown. It was not but, I swapped it out with another one anyway and bam! All four signals are working like a champ. I've owned several muscle cars and three 69-72's. This is my first square body but, I will say I've always had the weirdest gremlins with old GM trucks. Chevelles, Novas, Camaros are pretty straight forward but, these old trucks just need constant tinkering which is fine by me. They don't require a ton of money, I think they just enjoy your time spent with them. I hope someone searching the forum in the future finds this thread and it helps keep them motivated as I was about to just start using hand signals!
Ray is an incredible asset to this board when it comes to wiring! He has helped me and many others with wiring problems more than I can count! We have some really great knowledgeable members on here.
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