Subaru Outback Forums banner

21 - 40 of 49 Posts

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #21
I guess, recheck the fuse. Maybe it's blown. Let's get power back on pin 2 at the connector before going on.
The fuse shouldn't be blown, as all of the electrical functions of that fuse (interior lighting, navigation, fuel economy screen, and remote locks) still function. Also note that the dome light was still lighting up when I was taking measurements from it. Unless there is some other fuse I am not aware of. I was under the impression that blown fuses would prevent any electrical activity on the circuit, though.
 

·
Registered
Joined
·
17,808 Posts
Also note that the dome light was still lighting up when I was taking measurements from it. Unless there is some other fuse I am not aware of.
The "dome light" being the one in question, i.e., the light over the cargo area?

That being the case, there must be power to it, and that comes from the 3-wire connector, presumably pin 2, the middle pin. But, your previous post notes:
the measurements were taken from the wire harness only with no dome assembly attached.
If the measurement was made at the connector and the connector wasn't attached to the assembly, then there's no connection to the bulb! How could it be on? What am I misunderstanding?
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #23
The "dome light" being the one in question, i.e., the light over the cargo area?
I am referring to the light above the rear seats, not the one near the rear hatch. Maybe this will clear some confusion up.

If the measurement was made at the connector and the connector wasn't attached to the assembly, then there's no connection to the bulb! How could it be on? What am I misunderstanding?
I measured voltage between pin 1 and pin 2 by plugging the probes into the pins' respective slots in the wiring harness for the dome assembly (female end). That should still theoretically complete the circuit and indicate a measured voltage, no? I didn't think having the dome assembly attached to the harness was necessary for measuring voltage, especially if it's 12V coming from the car battery. That should be there regardless of whether the assembly is connected to the harness or not. For pins 1 and 3, I measured the voltage with the wire harness connected to the dome assembly by placing the red probe on the low side of the bulb (as you indicated) and the black probe on the metal tab on the dome assembly leading into the ground wire slot on the harness (pin 1). I am heading home now and will attempt to take some pictures to hopefully clarify any areas I may be confusing you. Thanks!
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #24 (Edited)
Dome light illuminated while all doors are shut:

485580


How I measured for voltage between pins 1 and 2 (please excuse the funky angle, was hard to hold and photograph at the same time):

485581


My multimeter configuration for the readings:

485582


Also checked the 10 amp backup fuse. Somehow, it blew, but changing it made no difference in there being no voltage reading between pins 1 and 2. Could a short be causing this? Only voltage reading is coming from pin 3 (far right), which is steady at around 14.2V. Is it possible that pin 2 is really pin 3 and vice versa? I confirmed that the fuse wasn't blowing on contact, as the one I just put in looks good after attempting to take some more measurements. Also, rereading your previous post, I believe I had the "low side" of the bulb mixed up in my reading, as I measured it from behind the bulb in the circuit (ground end) rather than in front of the bulb (pin 3 end).
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #25 (Edited)
Update: there is a steady 12.55V indicated on the low side of the bulb with the switch set to "door" and all doors closed, the low side being the side connected to pin 3. Used pin 1 as ground. Voltage only drops to 12.48V with a door open.
 

·
Registered
Joined
·
17,808 Posts
My error. I had interpreted "rear dome light" as the one in the cargo area. But I see that you are working with the light over the seats. There was no comment on my annotations in the wiring diagram that are with the "luggage room light", the Subaru reference for the cargo area, so I had no idea I was wrong earlier!

So, instead of being on page 3 of the wiring diagram, we're on page 2, dealing with the "room light", that also has a 3-wire connector, but different connections. According to the wiring diagram, at the room light:

Pin 1 has a black wire and goes to body ground;

Pin 2 has a black with red stripe wire, and goes to the BIU;

Pin 3 has a blue with red stripe wire and is connected to the fuse, along with many of the other lights in the wiring diagram.

We need to have battery voltage at pin 3 connector at all times.

When switched to "door" there should be battery voltage at pin 2 when all the doors are closed, but that drops down low, when any of the doors is opened.

Going back to what I asked earlier about the hatch, when all the doors are closed, are all the door-specific warning lights off. I presume so, but want to confirm.

Update: there is a steady 12.55V indicated on the low side of the bulb with the switch set to "door" and all doors closed, the low side being the side connected to pin 3. Used pin 1 as ground.
That is correct, based on the room light wiring configuration.

485590
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #27 (Edited)
Here is an up-close photograph of the dome assembly. Pins 1-3 go from left to right and the "on/off/door" switch is on the left side.
485591
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #28 (Edited)
Pin 2 has a black with red stripe wire, and goes to the BIU;
This is the only place where my wiring does not match your description. My pin 2 has a brown wire. Pins 1 and 3 match your description perfectly. I'm sure this does not matter much for our application, though.

Going back to what I asked earlier about the hatch, when all the doors are closed, are all the door-specific warning lights off. I presume so, but want to confirm.
Correct. All of the warning lights in the gauge cluster operate correctly, and all doors are closed. This is also evidenced by the fact that the front interior lights still turn on and off as they are supposed to when doors are open/shut.
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #29 (Edited)
With the doors closed, voltage between pins 1 and 2 through the dome assembly is around 1.80V. With a door open, the voltage is around 1.70V, but it fluctuates, and doesn't seem to be enough of a difference to be noteworthy.
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #30 (Edited)
I was able to access the BIU and found the harness that connects to the rear seat dome light, as well as the exact all-brown wire from the dome light's location in the harness. No obvious signs of damage to either the harness or the BIU's receiving end. That probably doesn't mean much, though.

Edit: I think what this tells me is that maybe the wires from pin 2 and pin 3 are contacting together somewhere, since both the "door" and "on" switches are receiving always-on power. That, or something happened in the BIU to cause power to always be supplied through the wire at pin 2. I think that is unlikely though, as most of the damage appeared to happen near the rear dome assembly and I haven't noticed any other signs pointing to a general BIU problem. Either way, the problem seems isolated to pin 2.
 

·
Registered
Joined
·
17,808 Posts
I think what this tells me is that maybe the wires from pin 2 and pin 3 are contacting together somewhere, since both the "door" and "on" switches are receiving always-on power.
Not necessarily. If they were contacting, the voltage at both 2 and 3 would be much closer. But as I understand it, pin 3 has battery voltage (12+ V) whereas pin 2 has 1.8 V.

But what could be is the brown wire from pin 2 is grounded somewhere along it's length. That would leave the light on when the switch is in the "door" position, and when a door is opened, and the BIU itself would normally ground the brown wire to turn on the light, the voltage goes down further, but varies, because the BIU uses a pulsed signal. This is one possibility.

Another is that the BIU itself is damaged inside, such that there is a short inside, but it's not absolutely zero Ohms. Again, that keeps the light on all the time, but when the BIU wants to turn the light on, there's a further reduction in the grounding path, and that reduction in voltage with the pulsing.

A next step might be to remove that connector at the BIU, and see if the light goes out. If it does, the problem is in the BIU. However, I'm not sure if it's safe to remove BIU connectors when the battery is still connected. So perhaps a safer approach would be to have the ignition switch at off (key out) and disconnect the battery (remove negative cable). Then measure the resistance from pin 2 to ground with the connectors at the door light and at the BIU removed. If there's relatively low resistance to ground, the problem is in the wiring; if not, the problem of the light remaining on is a fault inside the BIU.

By the way, good photos!
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #32 (Edited)
Thanks! I already disconnected the BIU harness. When I did that, all of the interior lights shut off (I did this without disconnecting the battery but with the car off and everything seemed to be fine). With the fuse pulled, there is no indicated resistance between pins 1 and 2 on the dome assembly when plugged in. Not sure how to go about measuring resistance on the BIU side.

Edit: resistance on the corresponding pin on the BIU is registering, but near 0 (~30.5 ohms). There is no measurable resistance being detected at the dome assembly between pins 1 and 2, as I stated above. There is also no indicated measurable resistance on the BIU end of the brown wire in its wire harness.
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #33
Here is a photo of the pin I am taking readings from on the BIU. It is the 4th one down on the left; the last one before the indentation. The photo was taken with the bottom of the photo facing the engine bay and the top of the photo facing the rear hatch.

485602
 

·
Registered
Joined
·
17,808 Posts
Edit: resistance on the corresponding pin on the BIU is registering, but near 0 (~30.5 ohms).
That could be the source of the problem.

Here is a photo of the pin I am taking readings from on the BIU. It is the 4th one down on the left; the last one before the indentation. The photo was taken with the bottom of the photo facing the engine bay and the top of the photo facing the rear hatch.
That is the correct pin (C4).

Let's compare that to other light control contacts. The cargo area light is controlled at pin #3, and, if if have it all straight now, there's no problem with the cargo area light staying on when it's set to "door" and all the doors and hatch are closed. Measure the resistance to ground at pin 3, which is the one just above #4 in your photo. (They're numbered 1, 2, 3, 4 going down in that left side row in the photo.) But before doing that, check to see if there's any voltage to ground at pins 4, and 3, given that the battery is still connected and these circuits are "always on".
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #35
That could be the source of the problem.


That is the correct pin (C4).

Let's compare that to other light control contacts. The cargo area light is controlled at pin #3, and, if if have it all straight now, there's no problem with the cargo area light staying on when it's set to "door" and all the doors and hatch are closed. Measure the resistance to ground at pin 3, which is the one just above #4 in your photo. (They're numbered 1, 2, 3, 4 going down in that left side row in the photo.) But before doing that, check to see if there's any voltage to ground at pins 4, and 3, given that the battery is still connected and these circuits are "always on".
No indicated voltage on both pins 3 and 4. Pin 3 is not indicating any resistance, just like pins 1 and 2 on the dome assembly. If I understand what you're saying correctly, it looks as though we've identified the BIU as being bad.
 

·
Registered
Joined
·
17,808 Posts
No indicated voltage on both pins 3 and 4. Pin 3 is not indicating any resistance, just like pins 1 and 2 on the dome assembly. If I understand what you're saying correctly, it looks as though we've identified the BIU as being bad.
Right.

No resistance between pins 1 (ground) and 2 shows there's no short to ground in the wiring at pin 2. So the only ground path for pin 2 is the BIU. The difference between the 30 Ohms at pin 4, and the high resistance at pin 3 is significant.

Unfortunately, at some pojnt in the bulb replacement etc, I suspect 12 V was inadvertently, but directly, connected to the BIU and that caused it to fail. (There can be 12 V there, but it's normally through the bulb, which limits the current.) In any event it will probably require the BIU to be replaced. Or, you could disable the "door" function at the assembly, and just have "on" or "off" via the switch.

I apologize for not recognizing the light that had the problem.
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #37
Right.

No resistance between pins 1 (ground) and 2 shows there's no short to ground in the wiring at pin 2. So the only ground path for pin 2 is the BIU. The difference between the 30 Ohms at pin 4, and the high resistance at pin 3 is significant.

Unfortunately, at some pojnt in the bulb replacement etc, I suspect 12 V was inadvertently, but directly, connected to the BIU and that caused it to fail. (There can be 12 V there, but it's normally through the bulb, which limits the current.) In any event it will probably require the BIU to be replaced. Or, you could disable the "door" function at the assembly, and just have "on" or "off" via the switch.

I apologize for not recognizing the light that had the problem.
No worries at all. Thank you very much for your help. I found a relative cheap BIU on eBay. It was $30 shipped. The part number is 88281AJ50A and was listed as compatible with my car. Can you confirm this to be true? And if so, how much should I expect for the reprogramming service cost? Thanks!
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #38 (Edited)
I have removed the BIU from the vehicle and inspected the circuit board. The damage is apparent, but does not look severe. I have taken photos and will link them below.

485606


485607


Do you think it is repairable? Not as simple as spraying electronics cleaner on the board, is it? If it's just that black IC (that's what it is, right? 3rd black square in from the top in the 2nd photo) I should be able to figure out how to solder a new one on. What do you advise? Worth the effort to not pay to have all of my stuff reprogrammed?

Edit: there is resistance on the IC in question. Looks like I finally found my culprit.
 

·
Registered
Joined
·
17,808 Posts
I found a relative cheap BIU on eBay. It was $30 shipped. The part number is 88281AJ50A and was listed as compatible with my car. Can you confirm this to be true?
ELECTRICAL PARTS (BODY). INSTRUMENT PANEL.. 2010 Subaru Outback 2.5L CVT Limited | Subaru Parts Online seems to confirm that part number, but check that the car details I used for that are correct. (Try the same website using your VIN; that should be more reliable.) List price is almost $300, but a Subaru dealer, or on-line Subaru part supplier, e.g., Subaruonlineparts.com , could well charge less.

how much should I expect for the reprogramming service cost?
I don't know. But on reflection, I recall seeing a post, perhaps in the last year or so, that said a used BIU could not be reprogrammed to a different car. Also, as noted earlier, the car won't start if the BIU has been swapped with one not registered to it. Consequently, the car would have to be driven to the dealer first, then the BIU changed in the shop, followed by the programming. Or, I suppose the BIU could be changed first, and then car flat-bedded to the dealer shop. In any case, checking with a dealer early-on is warranted because it would have to be "on-side" with the overall plan.

Do you think it is repairable? Not as simple as spraying electronics cleaner on the board, is it? If it's just that black IC (that's what it is, right? 3rd black square in from the top in the 2nd photo) I should be able to figure out how to solder a new one on. What do you advise? Worth the effort to not pay to have all of my stuff reprogrammed?

Edit: there is resistance on the IC in question. Looks like I finally found my culprit.
There could be other components that are faulty but are not visibly damaged.

As pin 3 and pin 4 of that connector on the BIU both control interior lights, they probably have similar, if not the same, circuitry. The two circuits could be traced out, and the related components compared to see if there are significant differences. This might reveal additional issues, including damage to the printed circuit board traces/connections, that would have to be repaired. It's probably doable, but better done by, or at least with the help of, someone experienced in this type of work. Wouldn't want to end up with more issues or damage when the "repaired" BIU is reconnected . . .

@brucep might have some suggestions.
 

·
Registered
2010 Subaru Outback 2.5i Limited
Joined
·
61 Posts
Discussion Starter #40
ELECTRICAL PARTS (BODY). INSTRUMENT PANEL.. 2010 Subaru Outback 2.5L CVT Limited | Subaru Parts Online seems to confirm that part number, but check that the car details I used for that are correct. (Try the same website using your VIN; that should be more reliable.) List price is almost $300, but a Subaru dealer, or on-line Subaru part supplier, e.g., Subaruonlineparts.com , could well charge less.



I don't know. But on reflection, I recall seeing a post, perhaps in the last year or so, that said a used BIU could not be reprogrammed to a different car. Also, as noted earlier, the car won't start if the BIU has been swapped with one not registered to it. Consequently, the car would have to be driven to the dealer first, then the BIU changed in the shop, followed by the programming. Or, I suppose the BIU could be changed first, and then car flat-bedded to the dealer shop. In any case, checking with a dealer early-on is warranted because it would have to be "on-side" with the overall plan.



There could be other components that are faulty but are not visibly damaged.

As pin 3 and pin 4 of that connector on the BIU both control interior lights, they probably have similar, if not the same, circuitry. The two circuits could be traced out, and the related components compared to see if there are significant differences. This might reveal additional issues, including damage to the printed circuit board traces/connections, that would have to be repaired. It's probably doable, but better done by, or at least with the help of, someone experienced in this type of work. Wouldn't want to end up with more issues or damage when the "repaired" BIU is reconnected . . .

@brucep might have some suggestions.
Good advice. Ironically, the part number of the BIU I ordered off of eBay matches the part number of my current BIU exactly. I would inquire about the BIU reprogram job with my local dealership first and confirm that it can be done before bringing my vehicle there to be serviced. I would like to think that a dealership possesses the tools necessary to complete this job, but I may be wrong. I recall seeing the thread you mentioned about the dealer not being able to do the job, but I thought that was on a gen 3 OB (if that makes any difference). I will heed your advice about consulting somebody else first before doing any "experiments" on the current BIU. Thanks!
 
21 - 40 of 49 Posts
Top