Fog Light Electrical Problem

[djpg2000]

So, I have a 2011 Toyota 4Runner Trail Edition and my fog lights won't turn on. I tested the bulbs with alligator clips from the battery and they turned on so they're good. Then, I checked the bulb sockets with a multimeter to see if there's any power coming through the wires and the passenger side has power and ground but the driver side has nothing. I also checked the fuse with the multimeter and there's power on both sides while it's plugged in so it's good.

Now I'm confused..Why isn't the passenger side lighting up if it's got power? My next step would be to check the relay but supposedly it's contained within the driver side junction box assembly and I don't think you can take that apart??? Is there a way to test the relay then? Should I just replace the entire junction box assembly?

Here is the junction box assembly link to buy from a dealer:
2010-2019 Toyota 4Runner Junction Block 82730-35410 | LaGrange Toyota

Here are actual pictures of the junction box assembly on eBay:
2013 TOYOTA 4RUNNER CABIN FUSE BOX OEM PN: 82730-35410 | eBay

I'm also attaching a diagram and schematics. Please let me know what you think. Any help would be greatly appreciated.

 

[Too Stroked]

Basics first:

- Fuses all checked and good?

- Headlights on?

The part that stumps me is that you say you have power at the sockets. If you have power there, you should have lights - unless you have polarity sensitive LED bulbs in backwards.

 

[djpg2000]

Basics first:

- Fuses all checked and good?

- Headlights on?

The part that stumps me is that you say you have power at the sockets. If you have power there, you should have lights - unless you have polarity sensitive LED bulbs in backwards.

Yes, headlights are on..lol. No LEDs, regular halogen. I checked the fuse with the multimeter and there's power on both sides while it's plugged in so it's good.

Well, I checked the sockets again and it looks like I made a mistake. The passenger side has power and ground but the driver side has nothing. Sorry about the confusion. I'll edit my post above. But why isn't the passenger side lighting up if it's got power?

 

[Too Stroked]

But why isn't the passenger side lighting up if it's got power?

You might have a ground problem instead of a power problem on the one side.

As for the other side, I'd start tracing back and checking for power as you go.

 

[djpg2000]

You might have a ground problem instead of a power problem on the one side.

As for the other side, I'd start tracing back and checking for power as you go.

So, now I'm extra confused but I think I know what I should do.

This got very confusing very quickly because this has been playing tricks on me and making me second guess myself. Here is a quick list of events:

1st Check: I believe both sides had power but can't remember for sure.
2nd Check: Passenger side had power but driver side did not.
3rd Check: Driver side had power but passenger side did not.
4th Check: Passenger side had power but driver side did not.

On the 4th check, I squeezed the prongs of the multimeter past the rubber on the back of the socket to test if the wires themselves had power. Passenger side had power but driver side did not.

Also, I clipped alligator clips to the terminals of the bulb and to one end of the prongs of the multimeter (the female side). Then I stuck the other end of the prongs of the multimeter (the male side) into the terminals of the socket that had power. But, the bulb did not light up so maybe there's not enough current?

My best guess at this point would be replacing the relay which I guess means replacing the entire driver side junction box assembly? What do you think?

 

[Too Stroked]

So, now I'm extra confused but I think I know what I should do.

This got very confusing very quickly because this has been playing tricks on me and making me second guess myself. Here is a quick list of events:

1st Check: I believe both sides had power but can't remember for sure.
2nd Check: Passenger side had power but driver side did not.
3rd Check: Driver side had power but passenger side did not.
4th Check: Passenger side had power but driver side did not.

On the 4th check, I squeezed the prongs of the multimeter past the rubber on the back of the socket to test if the wires themselves had power. Passenger side had power but driver side did not.

Also, I clipped alligator clips to the terminals of the bulb and to one end of the prongs of the multimeter (the female side). Then I stuck the other end of the prongs of the multimeter (the male side) into the terminals of the socket that had power. But, the bulb did not light up so maybe there's not enough current?

My best guess at this point would be replacing the relay which I guess means replacing the entire driver side junction box assembly? What do you think?

I hate diagnosing weird electrical problems over the internet. It's usually hard enough when I can actually lay my hands on the vehicle.

That said, you still didn't test for a good ground on the side where you had power. Add a temporary ground. The reason I keep coming back to this is because a wise Service Manger at the marina I used to work at once told me, "All weird electrical problems are a bad ground." And he was almost always right. Let's get the one side where you have power working first.

 

[djpg2000]

I hate diagnosing weird electrical problems over the internet. It's usually hard enough when I can actually lay my hands on the vehicle.

That said, you still didn't test for a good ground on the side where you had power. Add a temporary ground. The reason I keep coming back to this is because a wise Service Manger at the marina I used to work at once told me, "All weird electrical problems are a bad ground." And he was almost always right. Let's get the one side where you have power working first.

Ok. I'll tackle that part tomorrow and let you know. Thanks for all of your help so far.

 

[djpg2000]

I hate diagnosing weird electrical problems over the internet. It's usually hard enough when I can actually lay my hands on the vehicle.

That said, you still didn't test for a good ground on the side where you had power. Add a temporary ground. The reason I keep coming back to this is because a wise Service Manger at the marina I used to work at once told me, "All weird electrical problems are a bad ground." And he was almost always right. Let's get the one side where you have power working first.

On second thought, I knew I wouldn't be able to sleep tonight if I didn't try this last thing.

So......

I tried adding a temporary ground on BOTH sides in TWO different ways just to make sure. The passenger side had power this time and the driver side did not.
NEITHER BULB LIT UP.

Now what?

 

[Fern]

Check at the plug instead of the socket.

 

[djpg2000]

Check at the plug instead of the socket.

I'm sorry, I guess I was using the wrong terminology. When I was saying sockets before I actually meant plugs. I was testing the plugs the entire time. Any other ideas?

Also, the relay does make a noticably loud clicking noise when I turn the switch on. Some websites say that means it's bad and others say that means nothing or that means it's working so I just thought I'd mention it just in case it means anything in this case.

 

[Too Stroked]

I'm sorry, I guess I was using the wrong terminology. When I was saying sockets before I actually meant plugs. I was testing the plugs the entire time. Any other ideas?

So if you have power - and now ground - at the plug, do you have it making it all the way to the socket? You need a complete circuit. Tracking down electrical problems is all about tracing and verifying power from one end to the other.

 

[djpg2000]

So if you have power - and now ground - at the plug, do you have it making it all the way to the socket? You need a complete circuit. Tracking down electrical problems is all about tracing and verifying power from one end to the other.

Well, I would assume the sockets are fine because when I said I hooked up the bulbs directly to the battery and they lit up I actually never removed the bulbs from the sockets. I just put alligator clips on the prongs of the sockets and hooked them up to the battery...

 

[Too Stroked]

Never assume anything with electricity. You have to test each part of the circuit as well as each connection. Living up here in the rust belt, I've seen sockets and / or bulbs literally rust out and the connection fail.

 

[djpg2000]

Never assume anything with electricity. You have to test each part of the circuit as well as each connection. Living up here in the rust belt, I've seen sockets and / or bulbs literally rust out and the connection fail.

Well, I would say that's possible but highly unlikely because the sockets came brand new attached to the bulbs from the auto parts store a couple weeks ago..

 

[ElectroBoy]

Well, I would say that's possible but highly unlikely because the sockets came brand new attached to the bulbs from the auto parts store a couple weeks ago..

More info could be helpful. You say it’s a 2011. And now you are trying to get new fog lights to work.
Did you buy the 4Runner used?
Did the fogs used to work but now they just crapped out?
Did the fogs ever work since you had the vehicle?
Are the replacement fogs OEM?

 

[djpg2000]

More info could be helpful. You say it’s a 2011. And now you are trying to get new fog lights to work.
Did you buy the 4Runner used?
Did the fogs used to work but now they just crapped out?
Did the fogs ever work since you had the vehicle?
Are the replacement fogs OEM?

I bought it used a few years ago and the fog lights worked perfectly fine. I took it off roading and flooded the engine(yeah I know). Water level was only half way up the wheels but it happened. I was especially pissed since they advertise these things going through water. They had a track set up at the McCormick Place in Chicago for the TRD Pro and they drove it through the same level of water if not higher. Anyway, I had the engine replaced and the fog lights didn't work afterwards. Then, one day about 2 months ago they randomly started working again for awhile. Eventually, I replaced the bulbs with brighter Sylvania halogen bulbs and they continued to work for about a week until all of a sudden they didn't again. Now I'm here troubleshooting..

 

[ElectroBoy]

I bought it used a few years ago and the fog lights worked perfectly fine. I took it off roading and flooded the engine(yeah I know). I had the engine replaced and the fog lights didn't work afterwards. Then, one day about 2 months ago they randomly started working again for awhile. Eventually, I replaced the bulbs with brighter Sylvania halogen bulbs and they continued to work for about a week until all of a sudden they didn't again. Now I'm here troubleshooting..

Since from your earlier posts it seems like you have occasional voltage at the driver and passenger sides I would first suspect corrosion somewhere causing intermittent electrical connections.

First check at the sockets where the bulbs plug in. See if you can abrade down to shiny metal with a small tool like a sharp edge screwdriver or sandpaper. Then check the wiring harness socket/plug metal in the same way. Every metal electrical interface in that circuit that could have gotten wet needs to be checked, cleaned, or replaced.

Also check for broken wires wherever you can. Wiggle the harness wires around at the fog light socket, push and pull a little when checking the voltages or trying the lights to see if there’s an intermittent connection.

If you got water all the way into your engine fuse box you could have more corrosion in there which would require a lot more disassembly, inspection, cleaning, and replacing. There is a thread in this forum about disassembling the engine fuse box to get at the 140A fuse.
Good luck. Let us know your progress.

 

[Too Stroked]

Well, I would say that's possible but highly unlikely because the sockets came brand new attached to the bulbs from the auto parts store a couple weeks ago..

We must have a terminology issue here. A bulb consists of the glass portion containing the filament, plus a base that contains the electrical contacts. The fog light housing consists of an outer housing, as well as a lens and reflector. There is an opening in the back of the reflector that the bulb goes into. An electrical harness (wiring) has a plug on the end of it that connects to the base of the bulb.

 

[djpg2000]

We must have a terminology issue here. A bulb consists of the glass portion containing the filament, plus a base that contains the electrical contacts. The fog light housing consists of an outer housing, as well as a lens and reflector. There is an opening in the back of the reflector that the bulb goes into. An electrical harness (wiring) has a plug on the end of it that connects to the base of the bulb.

1st Picture: What I've been referring to as a bulb.

2nd Picture: What I've been referring to as a socket including and since post #10.

3rd Picture: What I've been referring to as a socket up to and including post #9 and a plug including and since post #10.

 

[Too Stroked]

1st Picture: What I've been referring to as a bulb.

2nd Picture: What I've been referring to as a socket including and since post #10.

3rd Picture: What I've been referring to as a socket up to and including post #9 and a plug including and since post #10.

#1 & 2 are the bulb. #2 just shows the (male) connector on the bulb - which appears to be in good shape BTW. If you have continuity between the two terminals, the bulb is good since that is a single filament bulb.

#3 is the (female) connector end of the harness - which also looks to be in decent shape. If you have power and ground at #3, your bulb should illuminate. This of course assumes that you have enough tension in the female terminals to make contact with the male terminals in the bulb. If you do not have power and ground here. the problem is upstream.