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Weird Dome light issue for just Drivers side Front and Back doors

Discussion in '5th Gen 4Runners (2010+)' started by markolomew, May 31, 2020.

  1. May 31, 2020 at 9:33 AM
    #1
    markolomew

    markolomew [OP] New Member

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    So, I've researched a ton, and I'm stumped. On my 2014 4Runner, my dome light inside the cabin quite coming on when it is switched to "door" setting. It will come on if I switch it to "on", so I know the bulb is not burned out. No doors will trigger the dome light to come on when opened. Just in case, I replaced all the door switches and nothing changed.

    When I open up the passenger front door, passenger back door, or the hatch door in the back, the "door ajar" light turns on on the dash. If I open up the driver's front door, or the driver's back door, the "door ajar" light does NOT turn on.

    Remember, I've already changed all the door switches out so that's not the issue.

    I've check the fuse box under the steering wheel, and the "dome" fuses under the hood, and everything looks fine.

    Like I said, I'm stumped, any ideas?
     
  2. May 31, 2020 at 12:26 PM
    #2
    Daytonaviolet

    Daytonaviolet TRD Bro

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    Does the courtesy light on the door turn on ?
     
  3. May 31, 2020 at 12:34 PM
    #3
    markolomew

    markolomew [OP] New Member

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    If "courtesy light" is the light that is on the footer of the actual doors, then yes, all for doors work when the doors are open/closed as they should.
     
  4. Jun 3, 2020 at 7:09 AM
    #4
    markolomew

    markolomew [OP] New Member

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    Is there a main fuse for that driver's side run of the door wiring??
     
  5. Jun 3, 2020 at 11:58 AM
    #5
    Daytonaviolet

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    Have you looked closely at the dome light switch ? Perhaps take a meter to it and measure.

    This is an odd issue.
     
  6. Jun 23, 2020 at 12:01 PM
    #6
    markolomew

    markolomew [OP] New Member

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    Still can't figure this out. Maybe some more background will shake something loose. I need to jump my car after the battery went dead. Immediately after I disconnected the cables from the battery and got back in, it smelled like ozone in the 4runner, like something electrical fizzled out. ideas?
     
  7. Jun 23, 2020 at 12:16 PM
    #7
    Daytonaviolet

    Daytonaviolet TRD Bro

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    Did you read post #5
     
  8. Jun 23, 2020 at 1:21 PM
    #8
    markolomew

    markolomew [OP] New Member

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    Yup, I read it. What points are you suggesting I read between? If it's the dome light itself, that's simple, I get nothing across the light bulb when the door is opened in auto mode. Do you have any suggestion anywhere deeper to try?
     
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  9. Jun 23, 2020 at 4:57 PM
    #9
    Daytonaviolet

    Daytonaviolet TRD Bro

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    I’m suggesting to remove the light switch and measure inside. You stated the dome light does come on, but not when the door is opened. Makes me believe it’s a setting issue on the switch. Tittle from off, always on and on only if door is open. You can measure continuity when the light switch is out of the truck.
     
  10. Jun 23, 2020 at 9:09 PM
    #10
    Old Red

    Old Red New Member

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    All dome and door lights, and the door ajar light are controlled by the main body MPX ECU that is part of the cabin fuse box. There is a smaller square black plastic ECU attached to the side of it. If you are not getting the dome to trigger, and the 4R is not sensing doors open on one side, then it's the culprit. Have you tapped into any wires behind the dash in that area?

    Combine those conditions with the fact that you mention the smell of ozone (never good when electronics are involved), and the MPX is probably cooked. Replace it, either new or used.

    -Old Red
     
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  11. Jun 24, 2020 at 7:57 AM
    #11
    markolomew

    markolomew [OP] New Member

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    VERY interesting. I'm checked every fuse and relay in both fuse boxes and they were all good, so it was driving me crazy. I did not check the MPX though, so I'll do that next. Thanks for the good ideas!
     
  12. Jun 24, 2020 at 11:04 AM
    #12
    Old Red

    Old Red New Member

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    If I remember correctly, all the inputs from the doors to the MPX are in the middle connector of the three. Start there checking the wiring for obvious signs before removing the fuse box to get to the MPX ECU.
     
  13. Jun 24, 2020 at 12:00 PM
    #13
    markolomew

    markolomew [OP] New Member

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    I didn't realize ECU's (used) are $100+. Well, that sucks! So I took a picture of the area, but didn't see any issues with the wiring, so that was a bummer. You are saying the circled area is the connector in question, correct?

    Screen Shot 2020-06-24 at 1.58.42 PM.jpg
     
  14. Jun 24, 2020 at 12:58 PM
    #14
    Old Red

    Old Red New Member

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    Yes, that’s the connector. No signs or heat or discoloration. Does anything smell burnt near the MPX or fuse box? Used is not too bad. New they are like 450-500.
     
  15. Jul 19, 2020 at 3:03 PM
    #15
    markolomew

    markolomew [OP] New Member

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    How do I remove the two cables to the left of the highlighed square? I got a replacement MPX but I can't get these two cables out.
     
  16. Jul 19, 2020 at 3:08 PM
    #16
    Old Red

    Old Red New Member

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    Towards the top of the two connectors in there will be a little black plastic tab in the black retaining lever. Press that down while gently pulling out near the top on the black plastic lever. It will swing out, and the connectors should come out easily. Installation is as simple as pushing the connectors in and pushing the lever back into the lock position.
     
  17. Jul 19, 2020 at 3:40 PM
    #17
    markolomew

    markolomew [OP] New Member

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    Bah, I didn't see the black tab! Well that was easier than I was expecting.
     
  18. Jul 19, 2020 at 4:27 PM
    #18
    markolomew

    markolomew [OP] New Member

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    Ok, so updates. I changed out just the Black box part of the MPX with the remainder being my stock unit. As soon as I plugged in the cables, it started smoking something fierce, so I quickly took out the wires. Obviously, the white part of the MPX is the main issue. So I took out the whole unit, and replaced it with the replacement I had. Funny thing is the driver's side passenger door is fixed now, but not the driver's door. I then swapped out the driver's door switch with another with another working one, and there was no change. I'm worried I fried something when I had the new "black" mpx in the stock "white" mpx holder. Thoughts? Pics below of the stock unit upon further inspection!
    IMG_20200719_181708.jpg IMG_20200719_181724.jpg IMG_20200719_182004.jpg IMG_20200719_182016.jpg
     
  19. Jul 19, 2020 at 5:09 PM
    #19
    Old Red

    Old Red New Member

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    Good lord batman! So something is obviously shorting to ground. To clarify the white fuse box and MPX pictured above are the originals that weren't working, not the replacements? What does the inside of the new MPX look like? I am assuming burned as well, same area?

    The burned pins are 1-4 on the fuse block and MPX. Pin #1 is Ground. Pin #2 is FLCY (Connector 2F #27) which is to the Drivers Door courtesy light switch , which triggers the dome light and light in the lower door when opening, and the door open indicator in the cluster. You have a short occurring when the door courtesy light is closed (door is open) which tells the MPX to ground pin # 1 on F8 (Pink wire, ground for courtesy light in driver door) and have more current going to ground than the MPX can handle . See the diagrams I attached/uploaded. Pin #1 on F8 and Pin #1 on the MPX connector are grounds and are burned the worst. The short is occurring at the driver door light with the bulb or wiring. Do you have an oem bulb in there, or is it an aftermarket LED?

    Screen Shot 2020-07-19 at 4.40.59 PM.jpg
    Screen Shot 2020-07-19 at 5.04.19 PM.jpg
    Screen Shot 2020-07-19 at 4.48.03 PM.jpg
    Screen Shot 2020-07-19 at 4.58.55 PM.jpg

    Screen Shot 2020-07-19 at 5.11.02 PM.jpg
     
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  20. Jul 19, 2020 at 5:16 PM
    #20
    markolomew

    markolomew [OP] New Member

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    Great information! The bulb in the dome is the OEM bulb. You are correct, those are the photos of my stock MPX that I pulled out. I didn't get a look at the guts of the new black MPX though. I should have. I can always pull it out later if you think that will help. I wish these things were easy to get in and out!
     
  21. Jul 19, 2020 at 5:28 PM
    #21
    Old Red

    Old Red New Member

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    Sorry, should have been more clear. Not the dome light, but the courtesy light in the lower door panel. OEM or LED? Check the wiring to see if it is shorted. Unplug the light and check the pink wire from the connector at the light to the pink wire on connector F8 #1 for continuity. Then check the red wire (+) from the light connector to the pink wire on F8#1. If there is a short you will see continuity. No continuity means no short in the wire run, and the bulb is suspect.
     
  22. Jul 19, 2020 at 6:21 PM
    #22
    markolomew

    markolomew [OP] New Member

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    IMG_20200719_193509.jpg IMG_20200719_193543.jpg IMG_20200719_193618.jpg IMG_20200719_195047.jpg IMG_20200719_195131.jpg OK, pulled it back out and inspected the board. There is a little burn marks and a pulled up tracing, so I did a little soldering and fixed the connection. Problem is, no change to my driver side door light. Ideas?
     
  23. Jul 19, 2020 at 7:34 PM
    #23
    Old Red

    Old Red New Member

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    Diodes D022 and D024 are toast on the top side of the board. Repairing the trace won't do anything if other components in the circuit are bad. That MPX is done. You need to trace the wiring from the driver side door light to the Fuse Box and MPX. Something is shorting to ground between those points, and replacing the MPX without finding the short will just keep frying good ECUs.

    Keep driver light bulb unplugged and battery disconnected while doing #'s 1-3

    1) With F8 & 2F Connectors Disconnected from Fuse box & MPX, Test From F8 #1 To I7 #2 for Continuity on Pink Wire. (Continuity = GOOD)

    2) Test entire length of Red wire From 2F #27 to I7 #1 (Continuity = Good)

    3) Test 2F #27 to I7 #2 (Red to Pink) and F8 #1 to I7 #1 (Pink to Red)

    3A) Continuity = BAD: If continuity between red/pink with no bulb hooked up, wires have shorted. Look between I7 to IF1 and IF1 to 2F and F8 to find location of the short and repair


    3B) Open = GOOD: with battery disconnected hook bulb/light back up and test #3 again to see if bulb is culprit.

    Screen Shot 2020-07-19 at 7.12.08 PM.jpg
     
  24. Jul 19, 2020 at 7:43 PM
    #24
    markolomew

    markolomew [OP] New Member

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    I'll run your tests tomorrow and report back. To answer your previous questions, the courtesy light was an aftermarket led light. I've actually changed all four of my lights to these Chinese ground projection-logo light things (which are pretty cool). All of them work except for the driver's door. I unplugged the driver's courtesy light and replaced it with the OEM one, no change...still dark. I think went to the driver's side rear door and swapped that working courtesy light with the one from the front that I took out. To my surprised, it flashed once, turned off, then started smoking. I yanked it out as fast as I could, replaced it with the working light, and it was back working just fine. So, the light from the driver's door is bad....even though i don't know if it's bad bc it's the "cause" or if it's bad and it was just collateral damage. I'll get back with you about the test above. Man, I wish i could just buy the circuit board instead. I really don't want to drop another $100+ on this just for a light.
     
  25. Jul 19, 2020 at 7:58 PM
    #25
    Old Red

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    Well that confirms my suspicions. Bad light shorted and caused the MPX to cook. I would remove all of those lights and chuck them in the trash. They aren’t worth frying ECUs.

    I’m not a betting man, but I would put a $5 on the wires to the front door light probably being ok. Report back with what you find. Still test them to confirm, but new MPX and some factory bulbs or quality LEDs and you should be back in business.
     
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  26. Jul 20, 2020 at 9:20 AM
    #26
    markolomew

    markolomew [OP] New Member

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    Disconnected battery, unplugged connectors and tested with a multimeter. I'm having issues with the red cable. Have testing each spot from your diagram, here is what I found (for the red wire):
    Full Red Wire Run: I7 #1 to 2F #27 = No Connectivity
    I7 #1 to IF1 #6 (Driver's Side) = Connectivity
    IF1 #6 (Driver's Side) to IF1 #6 (Cab Side) = No Connectivity
    IF1 #6 (Cab Side) to 2F #27 = No Connectivity

    Pink wire is great throughout. Then Rehook battery up and OEM courtesy light is "working" aka getting continuity when testing Red to Pink.
     
  27. Jul 20, 2020 at 9:37 AM
    #27
    Old Red

    Old Red New Member

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    I made a typo, my fault. See the diagrams I posted. The results you indicated are correct testing from I7 #1 to 2F #27. Instead of I7 #1 it should have been O5 #1 (Door open switch in the jamb) to 2F #27. This should have continuity. Next, with the battery hooked up and no bulb in the courtesy light socket, measure I7#1 for 12V with respect to the chassis ground. If 12V are there then you should be ok wiring wise.
     
  28. Jul 29, 2020 at 2:07 PM
    #28
    ElectroBoy

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    You’ve experienced a pretty common problem people have when replacing these door bulbs (usually with LEDs). If you don’t take apart the bulb housing cover to see what you’re doing, and you just start installing the bulb by feel, you can inadvertently short the leads together in the socket. And if you didn’t disconnect the battery first, and the door is open, the socket is powered with +12V from the ECU, and you fry the ECU.

    The contact region of some cheap LEDs look like little circuit boards with lots of exposed metal and they can be rather thick, so it’s real easy to push them into the socket at an angle and smash pins together and create a short. Since there’s lax quality control and no pre-testing of these parts, they can be shorted right from the factory, or just have crappy construction and fail shorted.

    In the future test all of your bulbs electrically before you install them. You can use a 9 volt battery. The Philips 168 (168ULWX2) LED bulb is a good reliable candidate for the door lights.
     

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