1972 MC 350/Auto - LED Head Light & Turn Signal Conversion

[B-Man]

I've been contemplating the LED headlights for a while. Getting older, I just want more light in front of me at night. But of course I don't want to blind people, which is why I'd hadnt made the conversion up until now.

Last week I came across a cool video on one of the first gen Facebook forums of "switchback" LED bulbs for turn signals. The idea is that when your headlights are on, the turn signals provide another bright white light bulb up front - more light!!! And when the headlights are off, so are the turn signal bulbs.

When you use your turn signals the lights switch to yellow - cool!! So when the headlights are on, and you use your turn signal, the white light goes away and the bulb blinks yellow on and off. And when the headlights are off, they just blink yellow when using the turn signals 

You do lose the yellow lights up front when the headlights are on. Until of course you use your turn signal.

I also bought some bulb-less 7in bezels for the headlights and installed LED light bulbs. They are pretty bright compared to the Wagner bulbs I recently bought off RockAuto.

Below are some pictures of the conversion. You can see the new LED bulbs in the passenger side - headlight and turn signal - and the incandescent bulbs in the driver side. Quite a difference!

It will be a while until I'm driving at night. But I will report back full results here when I do.

[jft69z]

I'm literally doing the same thing in my car (just the headlights though). I'll be posting pics tomorrow as well. I have the Hella Halogens I got a few years ago though, then I got Philips LED replacement bulbs to use last week. I tried a bunch of the other LED replacement brands when I converted my truck a few weeks ago, and the Philips seemed to be better than the other ones I tried (a bunch of import ones, and also Sylvania LEDs from Amazon), plus the reviews on longevity and durability seemed more favorable. They weren't the cheapest, but weren't the most expensive either.

Like you have found, night and day difference.

[B-Man]

Here is what I bought. No idea about quality and longevity. But they were CHEAP ... which of course may be a bag thing, haha

AUXITO H4 LED Light Bulb... https://www.amazon.com/dp/B092SHMWQZ?ref=ppx_pop_mob_ap_share

 

IPCW CWC-7006 7" Plain Round... https://www.amazon.com/dp/B001OMEPEU?ref=ppx_pop_mob_ap_share

 

Auxbeam 1157 LED Bulbs 1157... https://www.amazon.com/dp/B08D36F2KV?ref=ppx_pop_mob_ap_share

 

[jft69z]

10 minutes ago, B-Man said:

Here is what I bought. No idea about quality and longevity. But they were CHEAP ... which of course may be a bag thing, haha

AUXITO H4 LED Light Bulb... https://www.amazon.com/dp/B092SHMWQZ?ref=ppx_pop_mob_ap_share

This link didn't work for me.

Does this look similar to what you have?

https://www.amazon.com/dp/B097BWYYLC/ref=emc_bcc_2_i?th=1

[B-Man]

Hmmm it's not them.. yeah weird, the link isn't working . I will pull up the part number off the box later and post it here. 

[B-Man]

@jft69z, here is a picture of the part number label on the box. 

[B-Man]

I also bought new 1157 bulb sockets and will be installing them this weekend. One of the turn signal switch back bulbs was acting very funky. I went back and forth between passenger and driver side a few times and realized that the 50 year old sockets just aren't worth relying on, imagine that

 

GLL Stradard 1157 LED Bulbs Socket Holder Auto Car Plastic Waterproof Turn Signal Tail Stop Rear Brake Light Base Harness Plugs Connectors Pre-wired Wiring Sockets https://a.co/d/4gEUM9B

 

And I sort of said it earlier, but last summer I replaced the headlight bulbs, retaining rings, hardware and sockets. So this job was MUCH easier last night, not dealing with 50 year old screws, inserts, etc. it took me maybe 30 minutes to swap out both headlights and the turns signal bulbs - a quick job for sure.

[B-Man]

The 1157 bulb sockets above didn't fit. They have 4 plastic 'ears' vs the original having only 3 metal spring-ears. So I've ordered these:

Standard Motor Products S55 Pigtail/Socket https://a.co/d/eVSyzyf

[Tbo]

B-man Im having an issue with one of the parking lights staying Amber while the other is white. The turn signal for that light is also staying on. The hazards blink fine, but the switch back function isn’t. I replaced both flashers with led flashers. 

[DragCat]

8 hours ago, Tbo said:

B-man Im having an issue with one of the parking lights staying Amber while the other is white. The turn signal for that light is also staying on. The hazards blink fine, but the switch back function isn’t. I replaced both flashers with led flashers. 

Just a quick question to the group, since I had this issue on my blue oval......Are the flashers for the LED's polarity sensitive? 

[B-Man]

@DragCat all LEDs are polarity sensitive. They are electrical diodes, which are the equivalent of mechanical one way check valves. They can only be put into a DC circuit in one direction in order to function properly 

Note that with the 1157 type bulbs the little detents that stick out are at different longitudinal positions along the barrel. So they can only go in one way

[DragCat]

4 hours ago, B-Man said:

@DragCat all LEDs are polarity sensitive. They are electrical diodes, which are the equivalent of mechanical one way check valves. They can only be put into a DC circuit in one direction in order to function properly 

Note that with the 1157 type bulbs the little detents that stick out are at different longitudinal positions along the barrel. So they can only go in one way

Good info, wish the blue oval people followed the same rules 🤣

[B-Man]

I just wired in the new, correct sockets - easy peasy. I mated the yellow wires on the new sockets to the blue original wires. Then brown to brown and black to black. The regular 1157 filament bulbs work properly with the headlights and turn signals.

Interestingly, I'm getting some weird function with these switch back bulbs. One of them is very obviously not working properly. So maybe I got a bad set, or they are just of low quality. I'm going to return them (Amazon) and order a replacement set. Will see what happens. A little annoying for sure, but typical with these fancy new gadgety things, haha!

[DragCat]

7 minutes ago, B-Man said:

I just wired in the new, correct sockets - easy peasy. I mated the yellow wires on the new sockets to the blue original wires. Then brown to brown and black to black. The regular 1157 filament bulbs work properly with the headlights and turn signals.

Interestingly, I'm getting some weird function with these switch back bulbs. One of them is very obviously not working properly. So maybe I got a bad set, or they are just of low quality. I'm going to return them (Amazon) and order a replacement set. Will see what happens. A little annoying for sure, but typical with these fancy new gadgety things, haha!

Just saying, I ordered that laminated schematic awhile ago. Haven't had to use it but nice product. 

 

 

 

[B-Man]

After returning the other set of 1157 switch back bulbs, I've now ordered these:

PHINLION Super Bright White Amber Dual Color Switchback 1157 2057 2357 7528 LED Bulbs with Projector for Car Front Turn Signal Parking Lights https://a.co/d/a5Ae0t6

Admittedly, I do have a sneaky suspicion that something is up with the wiring for the turn signal on the passenger side. One of the original switchback bulbs is definitely bad. But there is some funkiness going on there when I swapped the bulbs between passenger and driver side. But the original incandescent  bulbs work fine.

We shall see once this next set comes in. Hopefully I don't have an electrical gremlin to troubleshoot!

[B-Man]

So I've got this next set of switchback bulbs in. The passenger side is still acting very funky. As it was with the other set. So although I want to blame the bulbs there is sufficient statistical evidence to suggest something is up with the passenger side blinker circuit.

Both turn signals work fine with regular incandescent bulbs. Weird.

Any ideas what would cause one side of the circuit to have intermittent function with the switchback vs regular incandescent? There must be a weak point somewhere. 

[B-Man]

On 3/12/2024 at 11:00 PM, Tbo said:

B-man Im having an issue with one of the parking lights staying Amber while the other is white. The turn signal for that light is also staying on. The hazards blink fine, but the switch back function isn’t. I replaced both flashers with led flashers. 

@Tbo, I'm just getting back to working on my Monte after about a year hiatus and going through my old posts.  I just saw your post.  You should DEFINITELY pay the $25 to become a member so that you can tag people.  It's VERY worthwhile, cheap, and helps out the forum tremendously. 

Yeah, you're describing the issues that I'm sort of having as well.  The passenger side turn signal acts a bit funky ... sometimes ... as I've described above.  I havent done any troubleshooting on it yet.  I need to drag an oscilloscope home from work and compare the voltage / current on the driver side vs the passenger side to get a better idea of what's happening.  There must be some sort of 'trigger' that makes these "switchback" bulbs do their thing.  And maybe the supplied voltage, or current draw, is right 'on the edge' of that trigger.   I'd rather not make a science project out of a $20 set of bulbs though, if someone has a better suggestion for implementation of those switchback bulbs.

[Scott S.]

Check your ground wire.... Any corrosion to the frame mount may cause a problem.

[DragCat]

35 minutes ago, Scott S. said:

Check your ground wire.... 

Rule # 1 for everything electrical 

I always check before I button everything back up. On my LED rear lights, passenger side would go out with a smidge to tight putting the lenses back on 🙃

[B-Man]

51 minutes ago, Scott S. said:

Check your ground wire.... Any corrosion to the frame mount may cause a problem.

Yep, good point. I replaced all of the bulb sockets because looked horrendous. But I also hoped that would solve the problem. It did not. I will have to trace it out to see where that passenger side headlight grounds out. Pretty sure it's right in the vicinity. Thanks 

[Scott S.]

Just under the light up towards the sub frame.

[B-Man]

@Scott S., jumping back to this thread to post an update / solution.

I was posting in another thread Dash lights don't work - HELP! about my efforts to get my dash lights working.  Turns out they are working (sort of), just not all of them and not as bright as they should be.  When playing around with the gauge bulbs I noticed that wiggling the flexible gauge circuit board made my passenger side LED headlight flicker!  Once I got a solid (temporary) ground to the gauge cluster flexible circuit board, that headlight flicker went away and the light was solid.

So ... the issue was definitely a ground.  I still havent checked the ground you suggested (I will though).  But the problem most definitely was solved behind the gauge cluster.  Crazy.

[Scott S.]

Old circuit boards can be finicky..... As can anything old. 

Glad you got a win on that one.  

[B-Man]

Running lights hack!!!!  So I had posted on another thread about issues I was having with my dash lights, which ended up being solved by daisy chaining a ground wire from the metal housings that make up the gauge cluster.  And after improving the ground, my 'switch back' front turn signal bulbs started working properly.

As part of my dash light forensics I noted that the fuse box is missing the TAIL LIGHT fuse holder.  And I was (no longer) using that + side of it to feed a new fuse box that I installed.

By some manner of reasoning I placed the jumper shown in the photo below in between 2 fuses.  What I ended up getting is DAYTIME RUNNING LIGHTS!!!  And I'm really liking having them.  The front switch back bulbs up front show as white, and then turn to yellow when I use the blinkers.  Pretty cool.

Another weird result is that the car will stay running IF the headlights are on AND I turn the key back and take it out.  That's kind of a neat feature if I want to keep the engine warming up and forget something when leaving the house (happens).

So yeah ... day time running lights!  Maybe my insurance premium will go down

 

[Robnhood]

On 3/15/2024 at 12:44 PM, B-Man said:

After returning the other set of 1157 switch back bulbs, I've now ordered these:

PHINLION Super Bright White Amber Dual Color Switchback 1157 2057 2357 7528 LED Bulbs with Projector for Car Front Turn Signal Parking Lights https://a.co/d/a5Ae0t6

Admittedly, I do have a sneaky suspicion that something is up with the wiring for the turn signal on the passenger side. One of the original switchback bulbs is definitely bad. But there is some funkiness going on there when I swapped the bulbs between passenger and driver side. But the original incandescent  bulbs work fine.

We shall see once this next set comes in. Hopefully I don't have an electrical gremlin to troubleshoot!

How did those Bulbs work?