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Discussion Starter #1
Hi guys. Have a bit of an issue regarding the interior lights on my 2010 Outback 2.5i. A while back, I did the full LED conversion for the interior and exterior of my vehicle. Unfortunately, before I knew better, I purchased CANBUS LEDs for the interior, which draw more power than traditional LEDs. They are largely unnecessary unless used in a car equipped with CANBUS so that a bulb error code isn't thrown due to the low power draw of LEDs. Well, somehow, I ended up blowing the 10 amp "backup" fuse in the fuse bank located under the hood, which I believe was triggered by a faulty festoon CANBUS LED installed in the rear dome light, but I'm not sure. My door locks, key fob, radio, navigation screen, and fuel economy screen were all not working because of this blown fuse. I blew 3 10 amp fuses in a row there and (stupidly) decided to substitute in a 15 amp fuse. Bad idea. Immediately it smelled like burning plastic so I knew I had damaged something but wasn't sure what it was (but hey, the fuse didn't blow, lol). Swapped the 15 amp fuse back out for a 10 amp and all was fine, everything was working again. Took me a couple of days to realize that my rear dome light was no longer turning on when I opened the door. Inspected it and found out that the bulb was toasted and so was the actual dome light assembly, so I ordered a used dome assembly off of eBay and replaced it. Plug n play. Turned on and worked. Yay.

Now the new dome light stays on when set to "door," and actually caused a total drain of my battery since I didn't catch it at first. It may also be noteworthy to mention that all interior bulbs in my car currently are LED with the exception of the bulb in the rear dome light, which still has the incandescent bulb it was shipped with inside (my new non-CANBUS festoon LEDs haven't come in yet), so I'm not sure if that has anything to do with it or not. Not sure if I damaged the body control module (or whatever causes the lights to dim gradually when turning off) or what. I hope that the damage was limited to the dome assembly, though that may be unlikely. Still not sure what caused the short in the first place, either moisture or a faulty bulb are the most likely causes. And yes, before somebody comments it, all of my interior lights are set to "door" and all of my door switches are working properly. The doors and trunk are all shut. When I close a door, the front lights both go out but the rear dome stays on. Not really sure what is causing this. The dome assembly appeared to be in good working order when I installed it. No obvious signs of damage or defect. Any helpful insight is appreciated. Thanks!
 

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Not sure if I damaged the body control module (or whatever causes the lights to dim gradually when turning off) or what. I hope that the damage was limited to the dome assembly, though that may be unlikely.
I've attached the wiring diagram for the interior lighting. The luggage room light (cargo area dome light) is on the 3rd page.

Always-on power goes to pin 2 of the three-wire connector at the dome light assembly. The switch is on the low side of the bulb.

When the hatch is open, does the hatch door open warning light show in the instrument panel, and when the hatch is closed does it go off?

When the hatch is closed, if the dome light switch is moved to Off, does it go off?

As the dome light is a used part, it could be faulty and connecting pin 3 of the light connector to pin 1, thereby grounding it and leaving the light on all the time?

Also, if when there was a burning smell, the wire going to pin 3 and the wire going to pin 1 shorted together, that too would leave the light on with the switch at "door".

A damaged BIU is also a possibility, but much better to first carefully go through all other possibilities; replacing the BIU can be expensive and requires programming by the dealer.
 

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Discussion Starter #3
Update: my non-CANBUS LED festoons arrived today. Installed 2 in the front interior lights and one in the rear dome. Problem still persists with the LEDs. Reinspected the dome assembly and the wiring harness. No signs of obvious damage to either.

When the hatch is open, does the hatch door open warning light show in the instrument panel, and when the hatch is closed does it go off?
Yes, the rear hatch warning light on the dash functions properly and the hatch is shut.

When the hatch is closed, if the dome light switch is moved to Off, does it go off?
Yes, when all doors are shut and when the switch is set to "off," the light remains off. That is how I kept it overnight and how I plan to keep it until I get this resolved.

As the dome light is a used part, it could be faulty and connecting pin 3 of the light connector to pin 1, thereby grounding it and leaving the light on all the time?
Could be, although it seems unlikely. I will recheck the listing and perhaps contact the seller.

Also, if when there was a burning smell, the wire going to pin 3 and the wire going to pin 1 shorted together, that too would leave the light on with the switch at "door".
May be a noob question, but how would I test for and or rectify this? There was definitely a burning smell. It may also be worthwhile to note that, with the incandescent, the light was slightly dimmer at the "door" position than the full "on" position. Not sure if that tells you anything or not. Thanks for the insight.
 

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Discussion Starter #4
Just checked, there is continuity between all three pins in the wiring harness for the dome light. This is a problem, right?

Edit: no continuity between any of the 3 pins on the dome assembly. Looks as though I fried something in the car 😬
 

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Just checked, there is continuity between all three pins in the wiring harness for the dome light. This is a problem, right?
So the assembly itself appears good, but not the wiring to it.

Is the "continuity" essentially a short, i.e., near zero Ohms? If there's shorts between all three pins of the harness connector B347, then the wire going pin 2, which is the 12 V supply, is shorted to the wire going to pin 1, which goes directly to a ground, and that should cause the fuse to blow. Is the "continuity" at some resistance level, but not a short? (Are you using the lowest resistance range on, presumably, a multimeter of some sort?)

Incidentally, pin 2, the supply wire, goes to other lights, so when measuring from pin 2 to pin 1, your going through other bulbs and that could lead to a finding of "continuity".
 

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Discussion Starter #6
So the assembly itself appears good, but not the wiring to it.

Is the "continuity" essentially a short, i.e., near zero Ohms? If there's shorts between all three pins of the harness connector B347, then the wire going pin 2, which is the 12 V supply, is shorted to the wire going to pin 1, which goes directly to a ground, and that should cause the fuse to blow. Is the "continuity" at some resistance level, but not a short? (Are you using the lowest resistance range on, presumably, a multimeter of some sort?)

Incidentally, pin 2, the supply wire, goes to other lights, so when measuring from pin 2 to pin 1, your going through other bulbs and that could lead to a finding of "continuity".
Correct, the assembly appears to be good. I'm not very experienced in operating multimeters, but with the probes on pins 1 and 2 of the harness, the readout is near "020," appearing exactly like that with no decimals points. When connecting the two probes to pins 1 and 3, and 2 and 3, the readout goes crazy and reads "-594" for both. Not sure what to make of that. Seems like pins 1&2 might be near zero, but I can't tell. Mind you, these readouts are all from the continuity setting. I have not set the multimeter to measure for resistance.
 

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Discussion Starter #7 (Edited)
Also, when I place the red probe on pin 3 instead of the black probe, there is no indication of continuity with both pin 1 and pin 2. The screen goes completely blank but doesn't beep. Not sure what that means. When I pull the probes off, the screen returns to "1."

Edit: just confirmed that resistance is near 0 between pins 1 and 2. Depending on which probe is where, the resistance readings between pins 1&3 and 2&3 either results in the same blank screen I mentioned above or a readout of around -20 ohms.
 

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Pin 2 is powered, and that will throw off the meter. Better to remove the fuse. Even with the ignition off, there could also be some voltage at pin 3, which goes to the BIU.

Start by measuring the voltage between pin 2 and pin 1 (ground), and the pin 3 and pin 1.

Are you using a digital multimeter? (Post the brand and model so that we will be on the same page when it comes to its use.) If it is a digital multimeter, and, if there's no voltage when measuring between pin 3 and pin 1, measure the resistance between pin 3 and pin 1, with the red, positive lead at pin 3, and the black, negative lead at pin 1. It should be high. But if the BIU is damaged, or if there is a short to ground in the BIU wire, it would read low Ohms. Be sure there's no voltage on the wire at pin 3!)
 

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Discussion Starter #9 (Edited)
It is an "Allosun EM830" from Walmart. With the backup fuse pulled, the only pins showing noteworthy low resistance are still 1 and 2. 1 to 3 and 2 to 3 are both not indicating any shorts. The multimeter shows no change from the indicated "1" on the screen for both. So the issue appears to be solely between pins 1 and 2.

Edit: Voltage between pins 1 and 3 reads to be roughly 0.12V. No voltage indicated at pins 1 and 2. So it seems there is voltage on pin 3.
 

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It is an "Allosun EM830" from Walmart.
That's fine. I have ones like that . . .

With the backup fuse pulled, the only pins showing noteworthy low resistance are still 1 and 2.
That's odd. I can only presume the measurement is going through some bulbs that are part of the same lighting circuit, otherwise, if pin 2 and 1 are shorted, as I mentioned, that should blow the fuse.

[ What resistance range is used for this measurement? 200 Ohm? And, if so, what is the reading between pin 2 and pin 1. (Pin 2 is the middle pin -- easy to find. Pin one is an end pin, with a wire that is black with a yellow stripe.) ]

In any event, that would not lead to the light remaining on when the switch is at "door" and the door/hatch is closed. That would happen if the wire at pin 3 (which goes to the BIU), is either grounded in the harness somewhere along its length, or it's being grounded through the BIU.

Have to figure out how to reliably check that wire for shorts to ground, and isolate the BIU . . .
 

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Discussion Starter #11 (Edited)
[ What resistance range is used for this measurement? 200 Ohm? And, if so, what is the reading between pin 2 and pin 1. (Pin 2 is the middle pin -- easy to find. Pin one is an end pin, with a wire that is black with a yellow stripe.) ]
Yes, perhaps, although I did switch my front lights to the "off" position, so that may or may not eliminate the possibility of your theory of going through bulbs first. I believe the reading was taken at the 200 ohm standard. I will go back out and ensure that I don't have pin 1 and 3 mixed up. Where is the BIU, anyway? I'm sure I can scavenge a somewhat bargain used one and just pay the fee to have it reprogrammed.
 

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Discussion Starter #12
Here is what the wires look like on my harness. No yellow stripe on the black wire.
485524
 

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Discussion Starter #13 (Edited)
That's odd. I can only presume the measurement is going through some bulbs that are part of the same lighting circuit, otherwise, if pin 2 and 1 are shorted, as I mentioned, that should blow the fuse.
Also please recall that I did initially blow several 10 amp fuses in the backup location. That's when I switched to the 15 amp and presumably blew out the rear dome light. So, in a sense, the fuse was blown. Now it is not blowing, however. The replacement 10 amp fuse has been fine since the initial blowout event.
 

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Where is the BIU, anyway? I'm sure I can scavenge a somewhat bargain used one and just pay the fee to have it reprogrammed.
It's up under the dash on the driver side, between the accelerator and brake pedal.
The car would have to be brought to the dealer before the swap because it can't be started until the BIU is linked to the car and the security system including keys and fobs.

Here is what the wires look like on my harness. No yellow stripe on the black wire.
Perhaps it's the lighting in the photo, but the three wires don't appear to agree with the wiring diagram colors. Here's what we, supposedly, should see:
R347.jpg
Yes, perhaps, although I did switch my front lights to the "off" position, so that may or may not eliminate the possibility of your theory of going through bulbs first.
The exterior lights are not part of the interior light circuit. I was thinking one or more of the lights in the interior wiring diagram.

Pin 1 should have zero resistance to ground (e.g., to a clean metal spot on the car body).
Pin 2 should have 12 Volts (relative to ground) when the fuse is installed.
Pin 3, connected to the BIU, would have a pulsing voltage when the door is open when there's a bulb in the dome light, and 12 V when the door is closed.
(It's possible the colors were changed at some point in the production year and aren't reflected in the wiring diagram.)
 

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Discussion Starter #15
The exterior lights are not part of the interior light circuit. I was thinking one or more of the lights in the interior wiring diagram.

Pin 1 should have zero resistance to ground (e.g., to a clean metal spot on the car body).
Pin 2 should have 12 Volts (relative to ground) when the fuse is installed.
Pin 3, connected to the BIU, would have a pulsing voltage when the door is open when there's a bulb in the dome light, and 12 V when the door is closed.
(It's possible the colors were changed at some point in the production year and aren't reflected in the wiring diagram.)
Let me clarify please. By "front lights" I mean the front interior lights near the power sunroof controls. My bad for not clarifying. Pin 1 has close to 0 resistance (0.4 ohms showing on the 200 ohm setting). Pin 2 does not seem to be indicating any voltage, and pin 3 reads steady at 12.58 volts. Voltage on pin 3 does not seem to fluctuate with the doors open. Switching the front interior lights to "on" or "off" makes no difference in the readings. Please note that the front interior lights work perfectly as they should, including the fade to off feature and turning on/off with doors opening and closing. Not sure what that means for the BIU.
 

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Let me clarify please. By "front lights" I mean the front interior lights near the power sunroof controls.
Got it. "Front Lights" are the map lights, individually switched, but also can come on with the doors, and fade when they're closed.

Please note that the front interior lights work perfectly as they should, including the fade to off feature and turning on/off with doors opening and closing. Not sure what that means for the BIU.
The BIU uses a different connection to control the cargo area light. Looking at the wiring diagram, pin 3 of the light goes to terminal C3 of connector i84 at the BIU. The room light over the seats) and the map lights go to terminal C4 and D8 of the BIU, when they're set to work with the doors. The fact that these lights work properly with the doors indicates that the related circuits in the BIU are okay. The problem is isolated to the cargo area light system.

Pin 1 has close to 0 resistance (0.4 ohms showing on the 200 ohm setting). Pin 2 does not seem to be indicating any voltage, and pin 3 reads steady at 12.58 volts. Voltage on pin 3 does not seem to fluctuate with the doors open.
Something's not right.

Pin 1 connection to ground seems good.

With the fuse installed, pin 2 should have 12 V, i.e., battery voltage. The measurement is being made at the middle pin of the 3-wire connector at the cargo area light, with the connector not attached to the light assembly.

Pin 3 is somewhat of a mystery because there's no spec on what a voltmeter would read. So, for this test, the fuse is installed, the 3-wire connector attached to the light assembly, a good, incandescent bulb is in the assembly, and the light switch is set to "door". The voltage measurement is made between the low side of the bulb and a ground, the low side being the end of the bulb connected to pin 3 of the connector. (See attached) If there's 12 V coming from the fuse to pin 2 of the connector (which there should be), then, normally, with the hatch closed, or the switch set to Off, there should be 12 V on the low side of the bulb, i.e., on the pin 3 side of the bulb in the wiring diagram, and the light would be off. Then, with the switch set to "door" and hatch opened, that voltage would drop down to a volt or so and the light would be on.

Recheck/confirm these measurements; we'll see where that takes it.

It was mentioned that when the light switch is set to Off, the light goes off (that was used to save the battery), but that when the switch is in the "door" position, it remains on. Have you tried setting the switch to the ON position, with the hatch closed? I.e., is there a possibility the light switch is reversed and when it's in the "door" position, it's actually at On and the light just remains on as it should? Longshot . . .)
 

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Discussion Starter #17
I believe you are correct on all assumptions. Pin 2 shows no voltage with the fuse installed through just the harness pins. Connected to the dome assembly, pin 2 shows no voltage when switched to "off," around 1.46 volts when switched to "door," and -0.10 volts when switched to "on." This is with the original incandescent bulb. All measurements were with with the doors closed. Per your instructions, I am reading around 1.8 volts on pin 3 with some mild fluctuation on the low side of the bulb with all doors closed, and around the same but a bit lower with the doors open (around 1.7 volts average). And no, as awesome as that would be, the switch it not reversed 😅 so the issue is definitely somewhere else in the car and not in the dome assembly.
 

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Pin 2 shows no voltage with the fuse installed through just the harness pins.
I don't understand the latter part (bold).

If there's no voltage at pin 2, then there's no power for the light. If there's no power for the light, it can't turn on, let alone stay on, which is the problem to begin with.

Connected to the dome assembly, pin 2 shows no voltage when switched to "off," around 1.46 volts when switched to "door," and -0.10 volts when switched to "on."
Exactly how/where did you measure the voltage at pin 2? Describe in detail. Maybe some photos (worth a thousand words, sometimes). Could be just a misunderstanding.

We'll get to the bottom of this. . . just covering the bases . .
 

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Discussion Starter #19
I don't understand the latter part (bold).
What I meant by that was that the measurements were taken from the wire harness only with no dome assembly attached. For measuring the voltage on pin 2, the multimeter was placed on the 20V setting. The red probe was placed in the middle pin of the wiring harness with the brown wire shown in my picture above. The black probe was placed on the left pin with the black wire shown in my picture above. I am not currently able to share any pictures with you, as I am unfortunately not home at the moment. Tried reading the voltage with the black probe contacting both pin 1 (ground) and a bare metal surface on the roof of the car where the dome assembly would go. No reading for either technique, which is weird because I believe there was a voltage when I was taking measurements yesterday (when you made the comment about pin 2 being powered, which was likely the reason why my multimeter screen shut off when taking readings from it).
 

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I guess, recheck the fuse. Maybe it's blown. Let's get power back on pin 2 at the connector before going on.
 
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