06-16-2016, 10:22 AM
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#1
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low beams not working
[Cross posted from 4th gen forum because I realized later that it probably belongs here and I really need the help. This is for a 2006 4Runner.]
My low beams are not working. I've read several threads about this issue, and I've gone through all of the suggestions and troubleshoots in those threads, and they're still not working. I apologize if I missed some post somewhere that does give me the answer, but I promise I did my homework before posting.
Problem: low beams do not work. High beams work, high beam indicator works, fog lights work, tail lights work, basically everything works except low beams.
Troubleshooting performed:
* replaced bulbs with brand new ones out of the package despite visual verification showing the existing bulbs (fairly new) were undamaged
* checked the four fuses under the hood (left high, left low, right high, right low) all are fine and I swapped them around to ensure they didn't just have invisible breaks. (Are there other fuses to check somewhere?)
* swapped HEAD relay with brand new unit from store, no change (Is there another relay somewhere? Also, this relay does do both high and low beam, right? I was unable to find a second "head" relay and pulling this does kill the high beams. It seems weird that the same relay would control both. I did find a separate relay for the fog lights but not for low beams.)
* replaced turn signal / headlight control stalk (the thing on the steering wheel) with brand new unit, no change
* Looked at the wiring harness inside the steering column for obvious kinks and crushes and did not see any. I only have tilt steering, not telescopic, and the tilt steering hadn't been moved in years before doing this diagnosis so I doubt it's that but I did look as well as I could without taking out continuity testers and ripping apart my wiring harness
* volt meter in place of fuses under hood show no voltage across fuses for low beams when lights should be on, does show 12V across fuse for high beams when they're on
At this point, I'm at a bit of a loss, but I assume the fact that both low beams are out at the same time but nothing else is means there is some common failure point such as a ground, maybe, but I don't know where to look. It could also be a power lead, but since they are fused independently I don't know that that's what it could be. I've looked at the harness (from the outside) from the backs of the bulbs to where it disappears under the fuse box but have not pulled the fuse box to look under it because I wanted to ask the experts (you guys) for hints as to where to look for single points of failure for both headlights at the same time. And there's that nagging feeling about only finding one "HEAD" relay, but I've literally spent an hour or more reading and rereading the chart on the fuse box and the internal fuse box and looking around everywhere else for another place for fuses and relays as I have actually investigating and replacing the parts themselves.
Any hints or suggestions on what to do next?
Thanks!
~Patrick
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06-16-2016, 11:00 AM
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#2
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Join Date: Jul 2010
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Maybe these would help a little?!
Four different pictures, all of the headlamp system..
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01 SR5 - 187k+/- 285 BFG A/T KO2 - 99 talls & front Trekmasters / Rear KYB - Hella fogs - Taco Mod - Fixed gaping hole in frame {SOLD}
02 Taco - 197k +/- BFG A/T KO2 285s + rims from 4Runner - saving up for suspension - House gets priority over Taco (for now)
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06-16-2016, 12:38 PM
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#3
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cfranck1, that's really helpful. Thanks for the images; every other link I found was expired.
It looks like the one common line for both low beams is the power between the relay and the low beam bulbs. It can't be a ground wire, because the low beams share their grounds with the same-side turn signals, both of which work and it would be weird for both wires to break at the same time, anyway.
I found a post that mentions a "DIMMER" relay, which they say switches between high and low beams. But I believe that conversation was for 3rd gen 4Runners, which I believe uses a single bulb with high and low filaments so wouldn't be applicable to 4th gen and I don't see anything in the wiring diagram that you linked that would be such a relay. Also, a picture of the fuse box online doesn't have anything labeled "DIMMER" so I assume this is a red herring.
Would it be dumb to bridge from the battery to the "output" side of the fuse in the fuse box to rule out a connectivity issue on that side and isolate the issue to be upstream from the fuse?
Thanks,
~Patrick
Last edited by phoo; 06-16-2016 at 12:54 PM.
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06-16-2016, 01:58 PM
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#4
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Looks like everything gets fed from the "body" ecu??
Maybe that's bad?
Or you do have a bad wire somewhere?
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01 SR5 - 187k+/- 285 BFG A/T KO2 - 99 talls & front Trekmasters / Rear KYB - Hella fogs - Taco Mod - Fixed gaping hole in frame {SOLD}
02 Taco - 197k +/- BFG A/T KO2 285s + rims from 4Runner - saving up for suspension - House gets priority over Taco (for now)
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06-17-2016, 02:02 PM
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#5
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So, this is embarrassing, but I found the problem and the problem was the nut between the steering wheel and the seat.
To add a couple more points of diagnosis to make this thread useful for troubleshooting --
* Above I mentioned not having seen any voltage across the fuse. Well, that was because of a bad ground. Proven by the following: The power side of the fuse (the outside) to ground showed 12V (in other words, all of the control stuff up to the fuse worked fine). From the other side of the fuse, I got a bad ground. For both sides. Which doesn't make sense because the wiring diagram shows there's nothing but the lights between the fuse and ground. Remember, they both have their own path to ground, so there's nothing common between those two circuits at that point.
* This led me to believe that the bulbs were both burned out again. So I went to put the old bulbs I'd saved (remember, neither looked bad when I removed them) when I was really, really confused because the connectors were the wrong type. Yes, I'm an idiot and I replaced the high beam bulbs instead of the low beam bulbs when I started this journey. Sigh...
Thanks for the help. At least now I know exactly what is needed to add the "mist/temporary/pulse" function to the windshield wipers -- five screws, a wiper control stalk from another model that has that function, and five minutes of time.
~Patrick
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06-17-2016, 02:36 PM
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#6
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Member
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Good to hear you're back up and running!!
Sometimes the stupidest things happen to us?! We all do it..
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01 SR5 - 187k+/- 285 BFG A/T KO2 - 99 talls & front Trekmasters / Rear KYB - Hella fogs - Taco Mod - Fixed gaping hole in frame {SOLD}
02 Taco - 197k +/- BFG A/T KO2 285s + rims from 4Runner - saving up for suspension - House gets priority over Taco (for now)
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06-25-2016, 06:52 PM
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#7
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Join Date: Jun 2016
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destination for a little weekend
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06-23-2020, 11:43 AM
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#8
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Hi,
I’m having the same issue. 2007 Sport 4WD.
When you say the nut between the steering wheel and seat, can you be more specific? Where is this nut? If you shoot a photo, that would be ideal.
Thank you Patrick.
Quote:
Originally Posted by phoo
So, this is embarrassing, but I found the problem and the problem was the nut between the steering wheel and the seat.
To add a couple more points of diagnosis to make this thread useful for troubleshooting --
* Above I mentioned not having seen any voltage across the fuse. Well, that was because of a bad ground. Proven by the following: The power side of the fuse (the outside) to ground showed 12V (in other words, all of the control stuff up to the fuse worked fine). From the other side of the fuse, I got a bad ground. For both sides. Which doesn't make sense because the wiring diagram shows there's nothing but the lights between the fuse and ground. Remember, they both have their own path to ground, so there's nothing common between those two circuits at that point.
* This led me to believe that the bulbs were both burned out again. So I went to put the old bulbs I'd saved (remember, neither looked bad when I removed them) when I was really, really confused because the connectors were the wrong type. Yes, I'm an idiot and I replaced the high beam bulbs instead of the low beam bulbs when I started this journey. Sigh...
Thanks for the help. At least now I know exactly what is needed to add the "mist/temporary/pulse" function to the windshield wipers -- five screws, a wiper control stalk from another model that has that function, and five minutes of time.
~Patrick
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08-04-2021, 01:05 AM
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#9
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not sure I'm reading this correctly - did it turn out it was only the bulbs, and they both went at the same time? I just replaced mine about 20K ago so would be surprised if both gone but not unheard of.
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12-17-2021, 08:36 PM
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#10
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Join Date: Dec 2021
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I'm in the same boat and would love a picture of the bolt you're talking about. I have troubleshot down to the fact that the fuses have a bad ground.
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03-20-2022, 02:23 PM
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#11
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same issue
can. you share a picture or explain how you exactly fixed the issue? Can anyone else help here plz?
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03-31-2022, 11:01 AM
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#12
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Quote:
Originally Posted by happy camper
Hi,
When you say the nut between the steering wheel and seat, can you be more specific? Where is this nut? If you shoot a photo, that would be ideal.
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Just to eliminate any confusion for people, the nut between the steering wheel and seat, is him- OP. It was human error.
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