perplexing headlight question

[cmarnold]

Hello, everyone.  I'm newly registered to this site and have an odd one to request some insights into:

 

 

• [*]One low beam bulb (9005) does not work.  Swapped sides with the correct (and working), matching low beam bulb and the original side still did not work.  Brand new bulb tried on both sides to verify as the same.
  
• [*]All fuses were intact and the lighting-related fuses were checked for continuity and swapped around.  No change.
  
• [*]Swapped the high/low relays from one side to the other.  No change.
  
• [*]No power to the side not working but that's sort of to be expected from the diagnosis.  No visible corrosion or breaks in wires.
  
• [*]Front running, fog and turn signal lights all work.
  

 

Here's where it gets stranger:

• [*]No high beams on either side.  New bulbs (H11).  All fuses/relays swapped with no change.
  
• [*]High beam indicator light on the dash works when the lights are flashed or set to "on" (forward and back positions on the switch handle).
  
• [*]Cycling through the lighting options/positions on the switch works (minus the dead low beam and both high beams).
  

 

All of this occurred at once.  My wife claims to have heard some sort of "pop" sound but didn't think much of it.  I'm getting to wit's end as this just doesn't make sense.  I'm going to retest everything with my multimeter up and down the wiring harness but that's the last thing I can think of short of not driving it at night.

 

Thanks for any help you may be able to offer.

 

-CMA

[cmarnold]

Ooops...2014 Forester, BTW.

 

-CMA

[1 Lucky Texan]

did the 'pop' seem to be inside the cabin or outside/underhood?

 

did she smell anything odd?

 

was the car moving/driving?

[golucky66]

Unfortunately for a DIYer. On a 2014 Forester. The headlights are integrated into the body control module.

So electrical diagnostics because more difficult without access to what the module sees and is saying.

 

can you help us/me out. Does you car have:

Push button start?

Automatic headlights?

DRLs?

and is it a turbo?

 

Looking at the wiring diagram all of those things matter (some very small, other more important)

If you post back with info on that, ill re look at the diagram and see if I can pinpoint you to a few locations that can cause similar issues.

[cmarnold]

Unfortunately for a DIYer. On a 2014 Forester. The headlights are integrated into the body control module.

So electrical diagnostics because more difficult without access to what the module sees and is saying.

 

can you help us/me out. Does you car have:

Push button start?

Automatic headlights?

DRLs?

and is it a turbo?

 

Looking at the wiring diagram all of those things matter (some very small, other more important)

If you post back with info on that, ill re look at the diagram and see if I can pinpoint you to a few locations that can cause similar issues.

 

 

No push button start

Yes auto headlights

Yes DRLs

No turbo

 

Appreciate you and others responding to my plea for help before I hang my head in defeat and go to the stealership (no indie Subby expertise around here).

 

-CMA

[cmarnold]

did the 'pop' seem to be inside the cabin or outside/underhood?

 

did she smell anything odd?

 

was the car moving/driving?

 

I'll ask her.

 

Thanks,

 

-CMA

[golucky66]

So I spent a little while looking at the wiring diagram for the headlight system.

I’m going to start with the High Beams as it’s a little more complicated of an issue and system.
Also, I know you said you checked multiple fuses and relays and swapped some. Just for sake of preventing missing information, I’m going to assume you have done nothing so far.

High Beams Not working at all:

First and foremost. Do the DRLs work (if you don’t know what/where they are, they use the high beam bulb and step down the voltage to reduce brightness of the bulb) So, when key one engine running, headlight switch in the OFF position. Do the high beam bulbs light up at all?

 

If they do, you have an issue with one or more of the following:
DRL relay sticking
No power going to DRL relay (gets power from Fuse #15)
No ground getting commanded from the body control module (BCM).
 

Diag Procedure:

Check for power fuse #15

Temporarily jumper pin 5 to pin 4 of the DRL relay socket (relay removed)
Do the high beams go bright?
       Yes: Check for ground on Pin 3 of DRL relay socket when key on and high beams turned on

                   If you have a ground relay is sticking (swap to confirm)

                   If you do NOT have a ground: Issue is with BCM not supplying ground. Need scan tool
       No: Jumper pin 5 to B- (battery negative)
             Now do they work?
                     Yes: Issue with ground circuit on pin 4
                     No: Issue pre DRL relay with circuitry
 

 

If DRL do NOT work when following above step
Note: Might need to have key on or even engine running to follow steps below

 

Check for power at fuse #7 and Fuse #15 (make sure you check both sides)
Check for power at pin 5 of DRL relay socket
Check for ground at pin 4 of DRL relay socket
Check for power at pin 1 of DRL relay socket
Check for ground at pin 3 of DRL relay socket when high beams are “turned on”

 

If above is all good. Jumper pin 4 to pin 5 of DRL relay socket.
     Do high beams work?
          Yes: Try swapping relay with another known working one
          No: Jumper pin 5 to B- (battery negative)
               Now do they work?
                   Yes: Issue with ground circuit on pin 4
                   No: Issue pre DRL relay with circuitry (start checking for power and ground at headlight bulb)

 

 

 

Pinout for DRL relay

Remove relay and it will look like a T

 

I'm actually talking about the alphabetical letter T in the next sentence.

Top left of the letter T is pin 1, center of T (intersection of both line) is pin 2, and the top right is pin 3. Right below pin 2 is 4 and the bottom of the T is pin 5

Use this for diag above.

 

 

If you want, you can try disconnecting the battery and leaving it that way for an hour or two to "reset" the BCM. If it's an issue with the BCM input/output.

Edited November 30, 2017 by golucky66

[golucky66]

As for the low beams.

 

You said you have power at the bulb socket of the one that's working, and no power for the one that's not working.

 

It appears there are two fuses that power the low beams (this low beam electrical diagram doesn't make a whole lot of sense, so I'm going to do the best I can)

 

Check for power on both sides of both 15A fuse. One of the fuse below the DRL relay (closer to the front bumper) and the one on the right out of the two there.

The other fuse is the one that's one relay over from the DRL relay. Closer to the drivers side fender.

 

The first fuse I mentions above is pin 10 & 11

The second is pin 25 & 26

With both the higher numbers (11 and 26) being the side of the fuse closer to the windshield.

 

Check for continuity from pin 11 and right low beam bulb

Check for continuity from pin 26 and left low beam bulb

 

I know one of the low beams work, but it'll give you a frame of reference

 

And also, check for a ground on the bulb socket(s)

 

 

That's the best I can do for now. If you have any more questions or get part way through the steps and find a problem, either PM me or just post back here. I'll do the best I can to help without being with the car.

 

And I'm not sure where in MA you're located. But I work at a indie Subaru shop in Cromwell CT. If you can get it to my shop (if all this fails) I'll get to the bottom of it for you and get it back up and running.

Edited November 30, 2017 by golucky66

[golucky66]

Thinking about this a little more. I don't know why my diagrams didn't show the high and low beam relay (not the DRL relay)

 

So just to make sure.

If you do have a low and high beam relay... Follow the next sentance.

If you don't. Ignore it

 

Check that each of those relays has power on one of the bigger spades, and a power and ground on the smaller ones (make sure you have the low beams or high beams on when testing)

Edited November 30, 2017 by golucky66

[bstone]

Cut the wires from the nonworking side and leave room to splice in wires from the working side. I’ve seen many mechanics do this.

[keith3267]

I believe the transmission must also be in gear for the DLR's to come on.

[Fairtax4me]

Go Lucky I admire your enthusiasm to post all of that but that's way complicated for tracking down the problem.

 

First we just need to narrow down where to look.

 

We know the headlamp switch works, and that the hi/lo dimmer switch works. The BIU only takes input from these and uses that to control the headlamp relays.

The high beam indicator works, which tells us the BIU is commanding the high beams on, and therefore that the hi/lo switch works. And we know that the headlamp switch works since we have at least one working low beam lamp.

From there it's just a matter of power getting to the bulbs.

Check at the bulbs, power and ground. No voltage? Check fuses for power on both sides in both low and high beam positions. The little tabs on top make perfect spots to probe with a multimeter or a test light.

We should have power at at least one fuse since the one low beam lamp works. This also tells us the low beam relay is being commanded On and is working. So if both low beam fuses have power, the problem is between the fuse and the lamp.

 

Do the high beam fuses get power with the high beams selected? If no, Can you hear the high beam relay clicking on and off as the high beam switch is moved?

 

If the high beam fuses have power, then we're looking for a common connector or section of wiring between the fuse block and the headlights where there may be corrosion and now possibly burned wires. It may even be the one on the bottom of the fuse block.

[heartless]

I believe the transmission must also be in gear for the DLR's to come on.

 

Depends on the car - my 2002 Forester, yes, it had to be in gear

the other half's 2006 LL Bean Outback, they are on immediately with the key, even in park