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Side Marker LED Swap

1585 Views 13 Replies 2 Participants Last post by  charlie.munoz88
Has anyone besides rtlawlor swapped or changed out the LEDs from Amber to Blue, White or Red? I'm trying to determine the SMD's size, but can't figure it out.

The LED's look to be 6 pin (PLCC6), but are smaller than they common 5050 PLCC6 led's.
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Those look like 5050s to me. Just measure the white part of the LED package with a caliper. It should be 5mm square.

You'll want 12V versions, of the type that is a single color only (there are types that have separate RGB signals, and types that are controlled with a serial data stream.
Measurements correlate to those of 3528 (3.5mm x 2.8mm). These are the ones that I have ordered so far, just waiting for them to arrive so I can test them out.

I've ordered from different sources in order to see which work best.

Here's a size comparison of the 5050 PLCC6 SMD's and the 3528 PLCC2 SMD's to the SMD Led's on the board.

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There was no real data on the second one you linked to. The first and third ones you linked to clearly says they're for automotive use. But they're only 3V diodes. I can't tell if there's anything on the back side of that PCB, but on the front I just see resistors and a diode. And while it's possible the resistors are arranged as a voltage divider to provide 3 or 4V to the LEDs, I don't see why GM would have done it that way when they could have just used 12V LEDs.

So what I'm saying is, it's possible those LEDs you bought will burn out the moment you power them up.

Do you own a Digital Multimeter?
I do own a Digital Multimeter and from what I've been told the LEDs (factory ambers) are 3V. On my ATS-v the side markers happened to be 12V so I'm assuming at some point from 2012-2016 Cadillac made that change.

Here's what the backside of the PCB looks like
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Plug in the board so the lights will power up. Then take your meter and connect the negative lead to where it says "BATTGND -". Then probe each of the three leads on the right side of the rightmost LED. They should all be the same voltage. If the voltage is "0", repeat but use the left hand side of the leftmost LED. The voltage you read is the voltage the LEDs need to be. If you probe a side and there are different voltages on each of the three pins, this is an RGB type LED and those resistors are what sets the color and you could possibly change their color by changing the resistors (though again, why GM would do that, making it more expensive, I don't know).

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The car is currently at the shop getting some parts painted and some parts made in Carbon Fiber so I can't plug them in yet, but when I get the car back (hopefully some time late next week). Using the digital multimeter that I have, I was able to run a diode test. Based on that test, I was able to get a reading of 1.790V and the Amber LED to turn on when I connected the positive to pin 3 and negative to pin 5. It worked the same way on all three of the LEDs on the board.

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The meter's Diode Check function expects the diode to not be in a circuit with other components, so I'm not certain the measurement tells you anything more than the LED lighting up tells you - when forward biased the diode lights up. Though, indirectly, that's probably enough, it suggests the diode is a ~3V LED.

What the meter is telling you is what the voltage drop across the diode is. Once the voltage across the diode is equal to the voltage drop, the voltage drop will be the same no matter what higher voltage is applied to the diode. We don't know what the meter's voltage was, because the diode test is a current-based test, but it's likely the meter increases current until the voltage drop stops increasing, so the voltage it was at when that point was reached was the voltage actually displayed, 1.79V. If it was a 12V LED it wouldn't have lit at all at that voltage...
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Perfect, so far it's looking like the LED's I ordered may likely work. I expedited some over SMD's and they are stated to arrive this weekend.

@RocketSled Thank you so much for your help and guidance during this process.

I'm hopeful we will get them to work.
I received the SMD LEDs and swapped the amber ones out for the white LEDs. I tested using the same test and same orientation prior to inserting the PCB in the headlights and everything checked out. I then proceeded to install and plug into the cars headlight harness, but they won't power up with the the headlights on. Any suggestions?

I happened to see this on one of RTLAWLORs post and think that I have done the SMD LED swap differently and hence why it may not work. Looks like he removed the amber SMDs and then soldered short wire leads to another 3 led PCB board.

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The guy did it this way because he lacked the skills to do it right. The LEDs can be had on small PCBs, which it appears he bought instead of discrete components.

What you did should have worked.

Can you check for codes to see if the BCM is complaining about the side marker lights?

My guess is, the LEDs you bought are drawing too much current so the BCM shuts them off (think "circuit breaker" behavior). Do they maybe flicker, come on briefly before turning off?
Explain with more detail how you tested them, when you got them to light up? And while I don't expect to see anything, give me a closeup of one of the completed boards?
I attached the close up images of the board with the new SMDs soldered in. As for the testing, when I run the same test I described before (post #7) they light up, however when I plug the main headlight harness into the headlight (either Right or Left or Both) none light up.
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