2002 Lowbeam Wiring Issue?

[steiney]

Hello all,

Yesterday, my left fog light assembly popped off and was hanging by the wires. I noticed it during the day and figured I'd fix it later. Later that night, my friend was driving in front of me and called to tell me the low beam on the same side (left) was out. For the record, the high beam still works.

I tried replaced the bulb, but still the same problem. I pulled the fuse for that light but it is fine. I was wondering if the fog light is on a circuit with the low beam, so I put a bulb in the fog light but that didn't help.

So I'm guessing it's a wiring issue? I can't think of what else it could be. It's very suspicious that the low beam went out on the same day that the fog light assembly on the same side fell apart. Could those two possibly be related? Maybe the wires for the fog light have pulled out the wires for the low beam? I'm a bit of a novice with wiring stuff, so any help is greatly appreciated!

Thanks in advance,

steiney

 

[fourwd1]

Your fog lights may be wired so they can only be turned on if the headlights are on, but a bad fog light shouldn't affect anything.
Without knowing more specifics I'd guess a coincidence.

 

[steiney]

Your fog lights may be wired so they can only be turned on if the headlights are on, but a bad fog light shouldn't affect anything.
Without knowing more specifics I'd guess a coincidence.

Hey! Thanks for the insight. So if the possibility of a burned out bulb and the possibility of a broken fuse are both eliminated, is the only other option a disconnected wire? If so, I can only imagine it's a wire that runs to the fog light. Even if it doesn't require the fog light to be working to complete the circuit, I guess it could be part of a bundle that got pulled out when the fog light assembly popped apart.

Does that make sense?

 

[TheDurk]

Pretty sure it's the same harness (before a split.). Those stock headlight wires are very flimsy and after 13 years of heat and vibration and corrosion, it doesn't take much to snap the connection at the headlight socket. I think the fog could cause a pull hanging like that, but I'd have to look to be sure. Anyway, I'd check your wires at the headlight socket.

I just had to replace my headlight socket on that side just from age. NAPA has some nice sockets with pigtails made with heavier wire (14ga. I think) and the rubber shield mates perfectly with the boot on the headlight. Definite upgrade from OEM. $11 for a pair. If you need it:

NAPA AUTO PARTS

The other point is never trust a replacement bulb. Better to pull a working one from the other side to confirm the test. If it works, then put the new one on the side you pulled from and see what happens.

 

[steiney]

Pretty sure it's the same harness. Those stock headlight wires are very flimsy and after 13 years of heat and vibration and corrosion, it doesn't take much to snap the connection at the headlight plug. I think the fog could cause a pull hanging like that, but I'd have to look to be sure.

I just had to replace my headlight plug on that side just from age. NAPA has some nice plugs with pigtails made with heavier wire (14ga. I think) and the rubber shield mates perfectly with the boot on the headlight. $11 for a pair. If you need it:

NAPA AUTO PARTS

Awesome! Thank you for the link. I'm going to take a look under there as soon as I can to see if something came loose or if the wire actually frayed or snapped apart from corrosion or whatever. Hopefully it's something relatively easy to fix so I can do it myself versus taking it to the dealership. I guess those wires all have the plastic snap-together ends? Does that sound right?

 

[TheDurk]

Awesome! Thank you for the link. I'm going to take a look under there as soon as I can to see if something came loose or if the wire actually frayed or snapped apart from corrosion or whatever. Hopefully it's something relatively easy to fix so I can do it myself versus taking it to the dealership. I guess those wires all have the plastic snap-together ends? Does that sound right?

No, they are factory crimped to the sockets. If they break at the end, you have to replace the socket. (You could try some artistic soldering, but 1) that sounds beyond your skill set, and 2) even though I COULD do it, I chose not to. There is just not much wire to work with and I wouldn't trust it.

With the NAPA pigtail, you can use three crimp-on butt connectors (the red ones). Not preferred, but good enough to stay out of the dealer. I soldered and used heat-shrink tubing over the joint, but that's me.

See the edit I added about the bulb, too.

 

[steiney]

No, they are factory crimped to the sockets. If they break at the end, you have to replace the socket. (You could try some artistic soldering, but 1) that sounds beyond your skill set, and 2) even though I COULD do it, I chose not to. There is just not much wire to work with and I wouldn't trust it.

Gotcha. Yeah, definitely beyond my skill set AND tool set! I guess I'll let the boys at the dealership field this one. I hope I can return the bulbs I bought last night! Thanks again for your help.

 

[TheDurk]

Gotcha. Yeah, definitely beyond my skill set AND tool set! I guess I'll let the boys at the dealership field this one. I hope I can return the bulbs I bought last night! Thanks again for your help.

No, NOT the dealer!!! Seriously. If you can find the loose wire, crimping for a fix is pretty easy and worth learning how to do. Take a pic and we can help you through it. And double-test the bulb. We see bad new ones baffling people all the time on here. Also, swap the fuse side-to-side (or high-to-low, depending on whether you have DRL's). Fuses 'look' good but are dead all the time, too. Either use a meter or test light, or swap in a known good one, ALWAYS!!!

EDIT: Forget the fuse unless you have DRL's. No way low beam only on ONE side can be a fuse on the non-DRL circuit. But the rule is worth noting. If you have DRL's, there are 4 fuses, make sure you have the right one and check by swapping.

 

[steiney]

No, NOT the dealer!!! Seriously. If you can find the loose wire, crimping for a fix is pretty easy and worth learning how to do. Take a pic and we can help you through it. And double-test the bulb. We see bad new ones baffling people all the time on here. Also, swap the fuse side-to-side (or high-to-low, depending on whether you have DRL's). Fuses 'look' good but are dead all the time, too. Either use a meter or test light, or swap in a known good one, ALWAYS!!!

EDIT: Forget the fuse unless you have DRL's. No way low beam only on ONE side can be a fuse on the non-DRL circuit. But the rule is worth noting. If you have DRL's, there are 4 fuses, make sure you have the right one and check by swapping.

Okay, cool. I'll hold off on the dealership and see if I can use the info you gave me to solve the problem. Good point about the possibility of the new bulb being defective. I'll get under the 4runner tomorrow when I have a chance and see what it looks like. I'll post up a pic or two if I'm further baffled at that point.

I do have DRLs if I'm remembering correctly. I'll swap around the fuses just to be sure.

 

[RAD4Runner]

No, NOT the dealer!!!

Definitely not the stealer. One just quoted an officemate $5K to $10K for head gasket or cylinder head on a Toyota Sienna.

If you can find the loose wire...

Agree. Our senses are the best tools for troubleshooting the truck. You do not have to be an engineer to visually inspect for broken wire, loose crimps, etc. But if you have the money to pay someone else to do it, your choice.

Fuses 'look' good but are dead all the time, too. Either use a meter or test light, or swap in a known good one

Agree. Even a resistance check may not tell if fuse is barely conducting electricity. The best way to test a fuse is with it's current load running through it.

Probe both sides of fuse for (Voltage DC) while headlight is supposed to be on. Good fuse will have zero voltage across it. (Ignore notes about truck dying or starter)

 

[steiney]

Definitely not the stealer. One just quoted an officemate $5K to $10K for head gasket or cylinder head on a Toyota Sienna.


Agree. Our senses are the best tools for troubleshooting the truck. You do not have to be an engineer to visually inspect for broken wire, loose crimps, etc. But if you have the money to pay someone else to do it, your choice.



Agree. Even a resistance check may not tell if fuse is barely conducting electricity. The best way to test a fuse is with it's current load running through it.

Probe both sides of fuse for (Voltage DC) while headlight is supposed to be on. Good fuse will have zero voltage across it. (Ignore notes about truck dying or starter)

Thanks for the info. I've got a multimeter so I'll use that and your info.

Believe me, I would like to avoid the dealership at all costs, but they're the only place I remotely trust that is open on the weekends. I work probably 60-65 hours Mon-Fri and absolutely cannot be without my vehicle so the weekend is my only option, unfortunately. I actually know the owner of my local dealership through a business colleague. The first time I went them, they tried to screw me, but I caught the service manager in his lie pretty good and told the owner about it. The service manager called me the next day to apologize and ask me to come back so they could "make it right". No charge for that work, I might add. So, I take it there now with the confidence that they won't pull any crap going forward. I may not know much about electrical systems, but I know plenty about not getting screwed in business!

 

[steiney]

I completely forgot to update you guys, but it turns out the new bulb I was using was defective! I ended up trying the right side bulb in the left side and it worked, so I went and swapped out the defective bulb at the store and sure enough, it worked. Problem solved. I really felt like an idiot for not trying that sooner. Oh well. Lesson learned.

Thanks again to everyone for all your help!

 

[TheDurk]

The other point is never trust a replacement bulb. Better to pull a working one from the other side to confirm the test. If it works, then put the new one on the side you pulled from and see what happens.

No, NOT the dealer!!! Seriously. If you can find the loose wire, crimping for a fix is pretty easy and worth learning how to do. Take a pic and we can help you through it. And double-test the bulb. We see bad new ones baffling people all the time on here.

You are not the first.

 

[hoe_nah]

instead of a new thread I got a quick question. my low beams only turn on if I flash my high beams. 2000 4runner. anyone off the top of there head have any idea?

 

[RAD4Runner]

instead of a new thread I got a quick question. my low beams only turn on if I flash my high beams. 2000 4runner. anyone off the top of there head have any idea?

You sure it's not your low beams coming on when you flash your high beams?
Low and Highs are in same housing, right?

Checked voltages across the 3 bulb terminals while you're doing this?

Got schematic? I have a first-gen but could help analyze circuit if schematic is posted (high-resolution please?)

 

[hoe_nah]

no I'm positive its the high beam coming on theb switches to the low beam after. I'm gonna check voltages tomorrow and try dig further into it

 

[RAD4Runner]

no I'm positive its the high beam coming on theb switches to the low beam after. I'm gonna check voltages tomorrow and try dig further into it

Also remember, IF your headlights are wired same as first-gens, one busted fuse will not mean no lights. Instead, because bulbs share a common terminal between low and high beam filaments, busted fuse will casue power to "leak" through the wrong filament of bulb with busted fuse to the other bulb and give you ODD combination of dim light on one side and one wrong but dim mode (lo/high) on other.