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Discussion Starter #1 (Edited)
I recently replaced my front turn signal / running lights with switchback LED bulbs. There are a number of threads on the forum describing this task which basically describe two techniques. The driver's side is not bad for access, but the passenger's side has the charger in the way, and you have to make enough room to work around it. The first of the two primary methods I have seen are to pull the screws holding the fender liner then disconnect the right side of the bumper and pull it forward. The other is to have an assistant hold the fender liner after the screws have been removed, then work one handed in the limited space available. As I am basically lazy, and I don't have easy access to an assistant, I figured there must be an easier way.

There actually are two problems to solve: 1. Get access to change the bulb. and 2. Install the load resistors to prevent hyperflashing. To change the bulb, I pulled the fender liner screws and several screws holding the short air dam to be able to move the area just under the bulb about 1/2 inch. I made a tool from a length of 3/4 PVC pipe with a slot in the end just over 5/8 wide and about 1 1/4 inches long. Using this tool I went up from under the car, (which I had driven up on blocks) and pressed the slot of the tool over the end of the light socket. It was then easy to twist the tool to remove the light and its socket from the car and let it drop down through the opening behind the bumper.


On the left you can see the tool on the light socket. The right shows the socket hanging down and the LED bulb installed.



I had some trouble trying to reverse the operation, as the tension of the wire kept pulling the socket out of alignment. I then removed the socket from the harness, used the tool to replace the bulb and socket into the housing, then I used the tool to plug the harness back into the socket without any problem. Replaced a few screws and the passenger side was done!

A word of caution: Be sure and try the light before replacing it in the housing. These bulbs are polarity sensitive and will only work in one orientation. If it doesn't light, turn it around in the socket.

The bulbs I used are from Super Bright LEDs. I used them since I know they make great products, they have the correct type of bulb for our vertical orientation (no lens pointing up), they are relatively short for our limited space, and their bulbs totally blank the white light while the amber is flashing. Some brands alternate white and amber while flashing and don't show up nearly as well.


This is how the new bulb looks on the passenger side.



About the resistors: The wires for both sides of these lights pass through a connector on the Driver's side. Since there is much better access on this side, I decided to locate both resistors there.

Once an engineer, always an engineer! I was worried about the temperatures the resistors might reach under sustained use of either the turn signals, or more likely for long periods of the emergency flashers, so I did some experimenting. I mounted the resistors on a heat sink I had. It was 4 1/2 by 4 3/4 with lots of fins. I hooked one of the resistors to a 10 volt supply which simulated 50% power like a flashing light would average. I recorded the temperature at intervals up to 15 minutes and plotted them. I then did the same for the resistor mounted to the heatsink using thermal compound. I then tried it with the resistor hanging in air with no heatsink as the vendors often tell you to do. After pulling the driver's side fender liner back and checking out my actual available space, I made a heatsink of 3/16 aluminum about 3 3/8 square, I also ran a temperature graph of this.


As you can see below, the resistor really gets hot hanging in mid air, but any of the heatsink combinations keep it relatively cool.



No comments please about the fact that I only energized one resistor. I know it will get hotter with both energized during emergency flasher operation, but my test was really to show if a heat sink would make much difference, and it obviously does.

I discovered when working on the driver's side that I actually had more room to work with the wheels turned to the left. When they are turned to the right the tire limits how far you can move the liner. Of course removing the tire would give you the best of both worlds, but as I said, I am lazy.

I decided to mount this smaller heatsink on the metal structure just above the horn. There is adequate clearance from any other parts to avoid any damage from the heat - even though it is much lower in temperature, it is still hot!

I then had to tap into the harness coming from the 6 pin connector. On my MY2013, the right turn was a light green/violet wire, the left turn light blue/white, and the ground, black.

A note about wire taps: According to the service manual, these wires are all 0.5 mm wires. This is about 0.020 inches or about wire size 24 ga. The Scotch Lock wire taps we all use (the red ones) are rated for a minimum wire size of 22 ga. I measured the slot that grabs the wire, and it is .025 wide, .005 wider than the wire diameter.

I opted for Posi-taps, which are expensive, hard to find, and reliable! They make one that is rated for 24 to 26 ga wire. They were too tight over the insulation and I had to slightly rework them to fit, but they work great. I think I would go one size larger next time, in spite of the ratings. Amazon does carry them, but not the size I needed. I went directly to posi-products.com.


This shows the taps into the harness wires on the left, and the cleaned up version on the right, which also shows the mounted resistors.



I am very pleased with the final results: The switchbacks look great, give a little extra close illumination at night and are a little more distinctive when showing a turn signal.
 

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Great write up and explanation for those who will follow. Great idea on making the pvc tool.

I am wondering why Chevy would bury access to an incandescent bulb that will presumably need changing. It should have been made much easier.
 

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Discussion Starter #4
Great write up and explanation for those who will follow. Great idea on making the pvc tool.

I am wondering why Chevy would bury access to an incandescent bulb that will presumably need changing. It should have been made much easier.
Or equipped with LEDs in the first place.

Dick
 

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To be fair, it is not just Chevy that is making bulb changes difficult. I have seen this on a Honda as well. Probably common across the industry with current body style trends that have sculpted seamless shapes around the front and rear.
 

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Your load resistor temperature chart - does this take into account that the resistor on time is very limited. The resistor is only powered during the turn signal on time. I also don't think many will run their turn signals for 15 minutes. Hazard flashers maybe longer. I installed mine similar to yours, on the driver side bolted to a PCB copper clad board.
 

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Discussion Starter #7
Your load resistor temperature chart - does this take into account that the resistor on time is very limited. The resistor is only powered during the turn signal on time. I also don't think many will run their turn signals for 15 minutes. Hazard flashers maybe longer. I installed mine similar to yours, on the driver side bolted to a PCB copper clad board.
I only ran it out to 15 minutes for the hazard flashers. I would expect the turn signals to never be on for more than a minute or two. Hopefully I will not be one of the drivers on the highway with my blinkers on for miles!

Dick
 

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Great write up. I find it humorous that you say you are lazy, yet did a full thermal study on the effects of a heat sink on your resistors, does not compute haha. I too love the Posi-taps and they are the only type of insulation displacement connector I would use on a vehicle.

And for future reference the size of wires listed in the service manual is actually cross sectional area of the conductor, not the diameter, 0.5 = 0.5mm², which is nearly equivalent to 20AWG. GM's standards for smaller wires is 0.5, 0.35, 0.22, and in rare instances 0.13, but the vast majority of non-power circuits will be 0.5. It has long been a go-to size for most automakers. In efforts to reduce vehicle weights though, we will see a progression toward the smaller wire sizes, where permissible, in the coming years (and potentially the shift from copper to aluminum wire).
 

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Discussion Starter #9
. . . And for future reference the size of wires listed in the service manual is actually cross sectional area of the conductor, not the diameter, 0.5 = 0.5mm², which is nearly equivalent to 20AWG. . .
Thanks camaroz1985, that's great information. I should have researched that better. Always glad to learn!

Dick
 

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Following the OP’s guide, I have obtained the list of items he used. The only thing I changed was using a finned heat sync. I also have solid aluminum stock I can use as well.




The compound I used. Way too much on the first resistor but much less on the second. Good thing isopropyl alcohol is used to clean it up.
yup, WAY too much......

Second resistor

My friendly cleanup master



Single ground wire via soldering and shrink tubing


Finished product awaiting installation with the Posi-Taps.

Just need to confirm correct wires to tap for right and left turn signals, and the proper ground for our 2015 Volt.
Suggestions welcome.


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Following the OP’s guide, I have obtained the list of items he used. The only thing I changed was using a finned heat sync. I also have solid aluminum stock I can use as well.




The compound I used. Way too much on the first resistor but much less on the second. Good thing isopropyl alcohol is used to clean it up.
yup, WAY too much......

Second resistor

My friendly cleanup master



Single ground wire via soldering and shrink tubing


Finished product awaiting installation with the Posi-Taps.

Just need to confirm correct wires to tap for right and left turn signals, and the proper ground for our 2015 Volt.
Suggestions welcome.


Sent from my iPhone using Tapatalk
Don’t use posi taps. Open wires exposed to the elements aren’t a great idea.
 

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Don’t use posi taps. Open wires exposed to the elements aren’t a great idea.
What would recommend? The small red included clips are really crappy compared to the positaps. Other that wrapping the connection in that elasti tape in an attempt to make it weather tight.

I was thinking compromised rubber coatings on the wires aren’t ideal. Just looking for the best option.


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What would recommend? The small red included clips are really crappy compared to the positaps.

I was thinking compromised rubber coatings on the wires aren’t ideal. Just looking for the best option.


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I used soldered heat shrink tubing with adhesive inside. It’s waterproof underwater so it will be fine behind the bumper.
 

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I used soldered heat shrink tubing with adhesive inside. It’s waterproof underwater so it will be fine behind the bumper.
Thanks, that is a good option. I am still new to the resistor modification but per the destructions, it looks like one side it tapped into power while the other goes to the common ground. Do they make a T style shrink tube with adhesive or am I misunderstanding to connections?

Thanks


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Thanks, that is a good option. I am still new to the resistor modification but per the destructions, it looks like one side it tapped into power while the other goes to the common ground. Do they make a T style shrink tube with adhesive or am I misunderstanding to connections?

Thanks


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I deppined the connector, removed insulation from the turn signal + put 1 wire off the resistor around the bare wire and covered it in heat shrink tubing and melted the solder/tubing.
 

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Thanks again!

So this is what I have done. I am still not entirely sold on tapping into the OEM harness for the resistors. In rummaging through all of my crap-in-a-box, I discovered a couple of things I purchased way back when just after purchasing the Volt. I initially wasn’t going to install these because of the mixed reviews.

They claim to be plug n play with no need to cut the OEM harness. I took the one I had and then cut down some aluminum stock and attached both resistors via heat sync compound and small #6 sheet metal
screws.


Since my metal ramps will not work on the Volt due to the extremely low valance, I used some 2x10 and built a quick set of ramps.
1 @ 4’
1 @ 3’
1 @ 2’
1 @ 1’
Plus an 8” piece to use as a safety stop


Initially, I did not catch the fact I used the wrong length on the ramp closest to the camera. Worked as planned so I will fix it tomorrow.

During the ramp test at work(during my designated lunch break), it all went as planned


Using just a few limited tools, I began the install. I will admit, the height the ramps lifted the car was perfect if you don’t mind working on your back. The one thing I would recommend, is that you make a simple PVC tool that the OP suggested. Either that, sacrifice a deep socket. The driver side is a piece of cake to access the turn signal bulb base. Unfortunately, if you have fists of ham like me, the passenger side is very tight, but doable. I am going to make a PVC tool just to make sure I locked the bulb base in and right. I will also have it in my toolbox just Incase I need to replace a bulb in the future.

All the tools I used for this mod., was a T-15, 1/4” socket and ratchet(for the tight space between the front tires and the inner fender liner), 1/4” driver and a 7mm driver. Simple hand tools to remove and reinstall the plastic from under the front end.





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Total time to do this was rather quick. Like others have mentioned, these LEDs need to be plugged in a specific way to function properly. If you just plug in the OEM socket, one way works or not. But by me adding the plug n play harness, I have added a couple of variables.

Initially, as soon as I plugged it in, the LED illuminated the Amber portion. So either the bulb was backwards or the harness was backwards. After a bit of fiddling with orientation, I got the results I was looking for.




Once that was fixed, I began buttoning everything back up on the driver’s side.

I then started on the passenger side. First removing the 1/4” screws from the bottom panel followed by the smaller ones holding the air dam and leading edge of the bottom plastic.



Note that one of these things is not like the others(bet the song started playing in your head) yup, I just dated myself...... The longest one goes in the outer corner just before the fender liner rolls up towards the tire.

Once I was able to disconnect the bulb base from the light fixture, I had to go through the same drill of getting the proper sequence so that the switchback LED worked as intended. Then the fun began of me wedging my ham fist into the tiny space. Finally after some colorful metaphors, I was successful.

Even with the aluminum stock as a heat-sync, these things still get very warm/hot. So using heavy duty zip ties, I made sure they did not come into contact with any plastic.


Here is the final results.





I will update any changes or failures I experience. Thank you to the OP of this thread and everyone who has contributed.

Cheers
Bugs



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