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Aftermarket side mirror turn signal LED not working... how to identify problem?

7K views 14 replies 5 participants last post by  h4ldol 
#1 ·
I installed some aftermarket MIT side mirror LED turn signals on my 2014 Sienna XLE a few years ago. I bought Limited mirror housings and kept the OEM mirror glass since it has BSM. The wiring is the MIT wires that go through the side mirror rubber tunnel (what is that called?) to the front door and down to the driver side footwell where it taps into wiring (not sure what wiring this is but it may not be that important I guess at this point) for the signal and power. It's been fine since then until I noticed a few months ago that the right LED signal is no longer working. I'm not sure the best way to identify the source of the failure without opening up everything again. Or rather, how to problem solve this most efficiently.

I figure the most likely spot of failure is likely failure of the actual LED light or where it taps into the wiring (although I think I switched the wire "posi tap" style connector (which is very unreliable) and instead stripped the end of the side mirror wire, opened up a small section of the car wiring to expose the copper strands, inserted the exposed tip of the mirror wiring, wrapped it around the exposed wires and taped it all up. I've done this type of wiring splice numerous times when I can't easily crimp connectors and found that it is pretty reliable, but that is one possible spot for the failure of the light.

If it's the actual light that is failing, can I open up the side mirror and use a multimeter to check that it's getting power and that it's failure of the light, or some other way to check for failure at the side mirror before I start pulling off kick panels and other interior trim pieces (I hate to remove because I've done it so many times now that the clips and holes are in danger of breaking)? Any suggestions on how to approach this, or any ideas on what could be the source of the side mirror LED turn signal not working would be appreciated.
 
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#2 ·
Could you pop off the small black interior trim panel that covers the wiring harness to the mirror and the fasteners that hold the mirror to the door and then pierce the insulation on the wires leading to the LED signal with the sharp probes of a multimeter or a simple unpowered test light? That would at least tell you if power for the LED signals is getting to the exterior mirror housing without having to do very much disassembly.
 
#5 ·
Ah thanks, I guess I need to learn more about the basics of multimeter use. I can definitely try that by popping off the mirror cover and piercing the wires. I'll try this tomorrow and see if I can figure out which wires to use as I don't have any documentation anymore.

No problems with mine so far using the MIT turn signal mirrors. I soldered all connections and wrap it with heat shrink. I would open the mirror covers and use a multi tester to check for power before getting into the kick panels and etc. Sorry to hear about your problem. If I remember correctly, there should be a pigtail on the inside of the door and you can check that out too.
Thanks, will give it a try! I took off the door panel last week to install new front door speakers and saw the wires coming down from the mirror and they at least were intact and looked fine, so I guess the next step is to check the mirror wiring.

I was also one of the early adopters of the MIT LED blinkers sso far they have been wroking great. IIRC there was a connector between the harness coming from the mirror and the one connecting the internal wiring. I have tucked below the fron knee panel precisely for this reason. Not sure if you have the same. I would also recommend opening the mirror case and using a multi-meter before opening up anything else
Thanks, I like the lights as well (aside from the original not-exact fit that required some reshaping to make the mirror cover fit properly). Guess I'll check the mirror wiring with the multimeter first then pop off the kick panel and check out the wiring connections I made years ago (maybe 4-5 years ago at this point). Other than that, I suppose the only problem could be failure of the wire at locations other than the connections, like if it got damaged in the door or under the trim pieces, but that seems less likely.

I figure it's either light failure, problems with the wiring where it goes down the mirror "neck" or through the flexible rubber tunnel (whatever the heck that's called) that connects the door and the cabin as those were pretty tight squeezes, or the splicing connections in the cabin.

Thanks for the help everyone, will give it a try tomorrow although rain may prevent that (sadly I have to do all my auto work outside on street).
 
#3 ·
No problems with mine so far using the MIT turn signal mirrors. I soldered all connections and wrap it with heat shrink. I would open the mirror covers and use a multi tester to check for power before getting into the kick panels and etc. Sorry to hear about your problem. If I remember correctly, there should be a pigtail on the inside of the door and you can check that out too.
 
#4 ·
I was also one of the early adopters of the MIT LED blinkers sso far they have been wroking great. IIRC there was a connector between the harness coming from the mirror and the one connecting the internal wiring. I have tucked below the fron knee panel precisely for this reason. Not sure if you have the same. I would also recommend opening the mirror case and using a multi-meter before opening up anything else
 
#7 ·
I wish I could solder them but I do my work on my Sienna parked on the street so it's too troublesome to try to solder anything (and I have poor soldering skills, maybe partly because of the lead-free solder I use). I agree about taking the time to do things the right way the first time, so disappointing that something went wrong.

Anyway, I finally looked up how to remove the covers again and found three thin wires, black, red and blue, going to the MIT LED light. Red I assumed is power for the yellow turn LED, black ground, and blue for the blue LED (never used it so don't recall). The wires are super thin and I think even poking my multimeter leads in there risk severing the wires, but I did it anyway! On the driver side (that works fine), the voltage reading was all over the place, probably because of the poor connection of the leads to the super thin wire but occasionally it would read around 12V. The non-working passenger side would not fluctuate at all and was about zero.

So, based on this, I presume that the issue is likely not the light itself but probably the wiring, either where it goes through the grommet "tunnel" connecting the door to the cabin or where it goes down the neck of the side mirror attachment. I think that more likely because when I installed it a few years ago (maybe 4 years ago) I did not realize there was a panel under the mirror that could be popped off to help fish the cable, and so that super thin cable may have been damaged going down the side mirror "neck" down to the door. I think that is the likeliest location of the problem, although it could be downstream of that too (in the cabin footwell area where it splices into the control wires).

Is there anyway I can confirm the location of the problem? Will the wires show 12V below (downstream) of the mirror neck if the problem is in the neck?
 

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#8 ·
Next step is to remove the door panel. There should be a pigtail there to check. If it acts the same way, your problem will be more on the inside. Check for continuity from door to signal mirror too to isolate the problem. No need to turn it on.
 
#9 ·
Okay, thanks. I have taken the door panels off/on multiple times the past two weeks installing new speakers twice and then installing some Dynamat, so another time won't hurt. I hate those skinny little wires... maybe I'll run some new wire (just two wires should be okay since I only want the turn LED and not the parking LED, correct?). Also, I think you were the one who wrote up how to install the MIT lights years ago... is it easiest to run wires down the mirror "neck" (mirror housing to the front door) by taking off the mirror housing completely (popping off the sail panel and then unscrewing the housing and attachment)? I'm also considering just getting the OEM Limited side mirror turn lights and putting those in while I'm at it...
 
#15 ·
Cool, thanks.

I did this twice on my 13 XLE where the pictures came from and on my 15 SE. All the tapping I did is from the same harness except for the wiring color difference where I indicated the difference in post #25. It should have stated for the 2015 SE and most llikely the LTD too instead of " For the 2015 non LTD". The 15 XLE may have the same thing as the 2011-2014 wiring because they don't come with DRL's.. Turn signal mirrors installation for 2011-2015
Thanks, I can't really visualize all this without looking in my car and seeing what the wiring looks like but hopefully it's as simple as making the same connections as my MIT turn signal light wires. I do want to replace those super thin MIT wires though, which is why I think my lights failed, when I install my Limited lights that I recently bought on Ebay and that are on the way here.
 
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