Apparently the Door Light Multiplex unit can be easily damaged because the door lights are controlled by solid-state switches inside the unit - and damage can be done to the Multiplex unit when inferior LED lamps are installed - or when an LED is installed with its cathode pointing the wrong direction (a.k.a. backwards) since LEDs are like diodes (well, they are diodes!) they need to be installed with the cathode going a particular way. Also, Can type LEDs are probably a bad choice to use because they could damage the solid-state switches in the unit - as they are typically larger with more individual LEDs making up the 'can' and operate with higher amperage. If you can find out where the Multiplex unit is located you might be able to track down where the fuse is located and check to see if the fuse that protects the unit is blown - that would be good luck finding a blown fuse! .

Not to scare you but LEDs can cause all sorts of problems because they can emit RF, they don't have a linear amperage draw like a filament lamp does, and LEDs require either a driver circuit or some type of modified equal to a driver circuit that might include a triac device and which is unlikely to be stable. All these things can create havoc with items you would never think could be affected by some simple LEDs - e.g. routers, remote controls, wireless phones, garage door openers, numerous solid-state devices, etc., etc. And LEDs or their driver circuits can back-feed its characteristic sharp amperage peak envelope signal, with or without the use of a triac, into an entire AC or DC electrical system and make it almost unusable.

What brand and type of LEDs have you installed in the doors, trunk, and wherever?

 

Well so far you do know somethings. I think anyway? So I went out to my car. started it, and open the door, it beep and showed that open door image in the speedo console. While the door was open I pushed the rubber pin in without closing the door. The open door indicator went off, showing closed. So are you saying the you put a known good working pin from the front door in, and it would not light the light, and would not show the door open when it was open and car running?

Have you went inside the door panel yet? See if something wire wise, or connector wise looks bad or test bad yet?

Here's almost the same problem (link below). I'm kind of confused about the link info though. Looks like it was a fuse to the door network computer controlling a certain block of lights? IDK? ? But I don't see how that would just stop one door from working? Is you Trunk light working, and all the others lights? In the Owners book there is a fuse in the Engine bay #9 that says door courtesy lights? If me.... I would pull that fuse check, replace with spares, see if it links to the Door net computer, maybe it Resets? What I would do. It just may end up being the door computer bad.

https://www.clublexus.com/forums/ls-...ed-swap-2.html

 

I have vleds for my 4 courtesy lights, my outside mirror puddle lights, trunk/cargo area light and my reverse lights. The only off brand LEDs I have in the car are for my vanity lights as the vleds were too bright. I found a right side used MPX module for a 2015 GS350 on ebay for $30 and it should be here tomorrow or Monday. My next question is if you know where that module is located for the right side 😅

 

Yeah, I swapped the sensor and the bolt right after I cleaned the area to make sure the bolt had a clean grounding point as those rubber sensors are a single wire with the bolt holding it in as a ground. Still did not work after swap 🥲

I have opened the door panel and the wiring looked fine, I will open it again today after my oil change and check the locking mechanism and search for the MPX module location. I still have no clue where the right side MPX module is located. I believe on the LS there is 1 for each door behind the door panel and unsure if the 4GS is 1 per door behind the door panel because when I removed the door panel the first time I did not find that module.

As for the fuse in the engine bay, I found the 7.5amp fuse for dome and courtesy light but if it was that my dome light would not work. Every single light on the car works except that rear right courtesy light 😭

 

Again, just what I would do. - That Fuse controls all including the MPX that controls the door light not working correct? So I'm guessing you did pull the fuse to see if the module resets correct?

Good you can get that module for $30. The thing is hoping that is is a good one, as I'm guessing you got used? Do you have a kid in a car seat or any other reason that that door is used more than the other backseat door?

MPX? The White Box top left at 3:38 in the Vid?

 

watakual - Have you tried installing a #194 lamp (like the OE lamp) in the courtesy lamp holder?

The reason I ask is because the door mpx module with solid-state switches may be controlling multiple lamp loads (e.g. all four doors and trunk for instance) so it could be if the entire load is too much, or if there is one or more LED that is playing havoc with the solid-state components in the module, the module may act weird with only one of its loads (the feed for your right rear door light). I suspect the problem is not a hard wire issue but is somehow associated/linked to the use of one or more of the LEDs you have installed. I wish you could snap your finger and have all OE #194 lamps back in the lamp holder sockets to see what the results would be...

 

I did pull the fuse to check it and put it back in.

I got a used one because a brand new one from Lexus is $400 💀. The seller did “say” it is tested and working.

As for the usage of that door. No kids yet so my rear doors are only opened when I wash the car, in which the back just gets a wipe down as it is used rarely and I usually never drive more than 1 person at a time and I would have never known of the light being out if I did not order new courtesy lights.. If the MPX does not fix the issue, I will truly wish I never ordered new lights so I would have not encountered this issue hahah

 

Actually thats a great idea, I will reinstall the OEM bulbs because when I installed the vleds I kept all the OEM bulbs with the gray plastic part inside the housing because the vleds were a bit bigger so I had to remove the gray plastic part. I will update when I get home from work and try the OEM bulbs. Thank you for the tip!

 

LEDs are electrically polarised and will only operate correctly when their positive terminal (also known as the anode) is connected to the B+ or supply positive and their negative terminal (also known as the cathode) is connected to the supply negative. So LEDs will only light with the correct polarity whereas a regular (filament) bulb does not care about the polarity. To add to the confusion some LED lamps are made to handle reverse polarity (basically making them bipolar) and others (most) do not (making them mono-polar). Some light sockets in Toyota products are wired in reverse. What is typically ground is hot and visa-versa. Why Toyota did that in many cases is anybody's guess... With that knowledge and thinking about your LEDs and what you've done may help you to figure out the mystery...

Will a LED work in reversed polarity? No, it will not light up. And LEDs have a low reverse breakdown voltage, so it may avalanche and be destroyed. This can also damage or destroy solid-state components that are used to switch LEDs on and off. The higher power white LEDs manufactured for lighting applications often have a reverse diode integrated with them as a safeguard against reverse breakdown damage, which adds to the confusion even further.

 

That is a good idea b/c has. But wait...... I thought you said when you went to install the new LED in that door the factory blubs light was already not working?

 

I'm a little confused about what your intention is/was by replacing the #194 lamps with LEDs. At first, since you were talking about your rear door light not working I just thought you were replacing the OE courtesy lights with projection ghost lights (like below). But now I think I understand that you only wanted to replace all the OE #194 lamps in the doors with LED bulbs. It sounds like the physical size of the LED lamps' base is quite different compared to the #194 lamp's base you are wanting to replace. That's a perfect scenario for problems...and when you throw in the potential for problems simply because of the characteristics of LED lamps that just adds to it, and can create quite a mess.

I would be curious to know if the projection courtesy lights I installed in my front doors (image below) would immediately work if plugged into your right rear door's wiring harness... I'd wager a few bucks it would. It might not, but then again, it might!

 

I think its really confusing now. lol! I also thought he was replacing the OE courtesy lights with the upgraded Lexus name projection ghost lights?

So even if...... I thought he said he was getting 12v from all except the one door that's not. Are you saying you think it blew and/or shorted something by plugging in the 1st 3 with the projector or wrong lights, then that's why the 4th has low to no voltage? Or that the 3 are draining or messing up the circuit current for distribution of 12v to all 4? Now with that, I ordered and installed the upgraded projection Lexus name ghost lights, on just my front 2 doors. All 4 work fine still. I've been meaning to get the other 2 for the rear.

 

Hey everyone, sorry I took so long to get back, I got off work and just finished my oil change.Lets back track to get everyone on the same page.

Around April 2021 I replaced the OEM lights with vled bulbs. Everything worked at the time. Fast forward to January 2022, I ordered glass logo lights from leon_carbonfiber on IG (did not like the clarity of the plastic ones) I went to install the logo lights and noticed the rear passenger was not working.

I just plugged in the OEM 194 bulb and it still does not work.

The car does not know/show when that rear passenger door is opened. Meaning when the door is open there should be an animation on the cluster that shows which door is open but that door is the only one that does not animate on the cluster. I have ruled out the rubber door jamb sensor by swapping with another door. I have suspicion to believe the MPX module located in the front passenger door might be at fault. I will remove the front passenger door to access the MPX module and check if all the plugs/wiring looks good because I checked the rear passenger door (door with the courtesy light issue) and everything looks good.