Jump to content

Could a bad head light switch kill 1 head light and not the other?


Recommended Posts

I had my drivers side low beam head light died. Passenger side is fine. Through all kinds of trial and error & trouble shooting, I pin pointed it back to the drivers side head light plug in the engine bay and found that the power wire (brown with a strip) is not getting it's power at the plug.

 

I stripped back some wire about 3" down on said wire to see if power was just getting robbed in the plug head itself maybe due to oxidization or just a bad connection. however, this reveled no power as well. Of course, I cannot follow this wire back endlessly to find the power loss as in enters a massive bundle so I have to start thinking it is the switch.

 

So, could a bad headlight switch actually kill 1 side and not the other. the dead head light sides front & rear parking lights, fog lights, brights are fine, just the low beam head light.

 

any thoughts would be appreciated.

Edited by Lex Talionis
Link to comment
Share on other sites

No. The physical headlight switch doesn't power the headlights directly. The wires coming out of the light switch contain control signals going into the Smart Junction Box (SJB), in which a small IC and a few relays give power to certain lights.

Knowing problems like this from the Mustangs (2005+), I suspect a problem in your SJB.

 

Bastian

Edited by blumi
Link to comment
Share on other sites

Check all fuses there may be a left and right lo beam fuse or a junction point in the SJB where left and right power leads join,a wiring diagram would help. Look for the wire in the SJB and see if it is powered at that point,May also be a bad relay contact,Marty

Edited by Depiry
Link to comment
Share on other sites

I agree, I think it might be a bad relay contact. Without having a wiring schematic, I would assume that the headlight switch pulls in the coil of a 2 pole relay and each pole feeds a headlight.

 

To save some time and aggravation, you might want to try replacing the relay since they are relativey cheap and easy to replace. It's also possibly that the brown wire with the stripe has come loose where it conencts to the relay base.

Link to comment
Share on other sites

unless someone can come up with something to check I have missed, I have made an apt to visit the dealer :( next week as I am tapped for ideas and trouble shooting.

 

If it is the SJB, I would rather them deal with it in warranty as I understand it is pretty much a sealed unit anyway. and for finding relays, I just do not think this vehicle is setup like older cars where I can pull relays and swap drivers for passengers to test that.

 

fuses, wiring (as far as I can follow), bulbs, connections, power/ground tests, all things that I can check have been checked from what I can tell.

Link to comment
Share on other sites

fuses at the fuse box, #7 and #8, were naturally checked and they were fine.

 

as for the SJB, not sure where that is located. As well, where the relays are for the headlights.

 

I cannot find a Ford Edge SJB wiring diagram via Google

 

Try swapping fuses 7 and 8 and see if the problem moves from the left to the right. That would be the most logical explanation.

 

Otherwise it looks like there is no relay in the power distribution box - it must all be in the smart junction box.

Link to comment
Share on other sites

Try swapping fuses 7 and 8 and see if the problem moves from the left to the right. That would be the most logical explanation.

 

Otherwise it looks like there is no relay in the power distribution box - it must all be in the smart junction box.

 

fair idea. though I did pull 7 & 8 and cleaned them, but for fun, I will swap just to try as that is a step I should certainly try as it would only take seconds.

 

What year is your EDGE I have 07,08 electical diagrams

 

'08

Link to comment
Share on other sites

fair idea. though I did pull 7 & 8 and cleaned them, but for fun, I will swap just to try as that is a step I should certainly try as it would only take seconds.

 

 

 

'08

I was waiting for you to have this issue with good ole retro solutions hid kit lexxy. You "blew out" your SJB. Just as I did before they offered an "edge specific" harness. Luckily, I'm cool with my dealer and they replaced the box under warranty......it would have cost $1,000 out of pocket. I checked all the same things you did.....to no avail. You need to take it to the dealer......and send retro a thank you letter for their wonderful HID kits !

Link to comment
Share on other sites

I was waiting for you to have this issue with good ole retro solutions hid kit lexxy. You "blew out" your SJB. Just as I did before they offered an "edge specific" harness. Luckily, I'm cool with my dealer and they replaced the box under warranty......it would have cost $1,000 out of pocket. I checked all the same things you did.....to no avail. You need to take it to the dealer......and send retro a thank you letter for their wonderful HID kits !

 

you were "waiting" huh? ;)

 

well, not much I can do about it now. yes, I was a pre relay harness adopter. Never really had any issues like some reported so it comes as a bit of surprise that 2 years in the SJB takes a hit. I have no plans to deal with it myself any more and already have an apt for tomorrow. I have been in contact with RS and do - now - have one of the Edge specific harnesses so going forward I will naturally use that. I guess I will just see how it all plays out with the dealer.

Link to comment
Share on other sites

UPDATE: so dealer says they checked it and found the "gem box" (maybe their word for the SJB) was throwing an error code on the RIGHT headlight (despite my drivers side being out)??

 

So, they run through some sort of reset test pattern, it triggers all the lights, the error code is gone, both lights now work... :huh:

Link to comment
Share on other sites

UPDATE: so dealer says they checked it and found the "gem box" (maybe their word for the SJB) was throwing an error code on the RIGHT headlight (despite my drivers side being out)??

 

So, they run through some sort of reset test pattern, it triggers all the lights, the error code is gone, both lights now work... :huh:

 

Probably meant FEM - front end module. I think that's just another term for the SJB. Sounds like they just rebooted it.

Link to comment
Share on other sites

yep.. I vaguely recall "module" and "reboot" being used. Surprised nevertheless as I do not recall ever reading about something similar here. either way, pretty good news as it seemed a simple fix and not as bad as thought.

 

Funny thing is, getting the drivers side number entry pad replaced (bulbs burned out in it apparently) and changing out a bad rubber window trim on rear passengers triangle window (it would smear like tacky thick grease when you touch it) will both take 4-5 days.. this took an hour to figure out.

Link to comment
Share on other sites

FWIW the GEM, or Generic Electronic Module, is the exact same thing as the SJB, or Smart Junction Box. Ford originally called it a GEM and then decided to confuse everyone and rename it to SJB. Do you by chance happen to know the code they pulled out of the SJB??

Link to comment
Share on other sites

Thanks L1TECH for the confirm on naming confusion..

 

I did not ask what the error code is/was but I will ask when I pick it up and I would "think" it would be on the paperwork.

 

but what was so odd, not only that some sort of "reboot" kicked the SJB back into working, is that they were very clearly saying that the passengers side threw the error and not the drivers side despite the fact the drivers side was the dead one. hmmm..

 

I will follow up when I have error code #.

Link to comment
Share on other sites

Glad you got it worked out Lex. We also had the green light go dim on the number pad on the door. It is the middle number that is barely lit. Dealer said ford would "kick it back" if they repaired it because they said it was lit........very dimly , but lit. Kinda pisses me off they wont fix it because there is an apparent led burned out.....which are supposed to last like 25 years. BTW, I had the car in for an unrelated issue with the retro solutions HID kit installed and apparently everyone in the shop was checking it out. Put everything back to stock and driver headlight would not come on......took it in and Travis, my service manager knew right away what caused the SJB to "burn out" as they put it.....he explained to me that the SJB needed to be replaced.....maybe they did just reprogram it......no one will ever know. I have sais it before and I'm saying it now......if you want HID's , make sure the car comes that way from the factory.

Link to comment
Share on other sites

FWIW the GEM, or Generic Electronic Module, is the exact same thing as the SJB, or Smart Junction Box. Ford originally called it a GEM and then decided to confuse everyone and rename it to SJB. Do you by chance happen to know the code they pulled out of the SJB??

 

headlight test "sjb" got code " b2a2f " and they "cleared the code and ran on demand. then did self test. possibly related to ssm 20508"

Link to comment
Share on other sites

but what was so odd, not only that some sort of "reboot" kicked the SJB back into working, is that they were very clearly saying that the passengers side threw the error and not the drivers side despite the fact the drivers side was the dead one. hmmm..

 

Maybe it's designed after the human brain: left side controls the right extremities and vice versa :hysterical:

 

Bastian

Link to comment
Share on other sites

headlight test "sjb" got code " b2a2f " and they "cleared the code and ran on demand. then did self test. possibly related to ssm 20508"

 

 

That code indicates a ground fault with the right lowbeam headlamp. When this happens it shuts down the low beams alltogether until the codes are cleared from the SJB.

Edited by L1TECH
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...