High Beam Indicator Comes On With Low Beams, Lows Do Not Work

Hi everyone, I have a 95 Tacoma 3.4, and im having a issue where when I turn my low beams on, no headlights come on at all, but the high beam indicator comes on on the dash. When I turn to highs, the high indicator stays on and the highs come on like normal. Ive tried another headlight relay and it does the same thing. Its also intermittent. Sometimes it does it, sometimes it doesnt. I just replaced the relay/fuse box underneath the dash because it got all corroded and the horn, radio, and 4 ways didnt work. The first time I tried it after installing the new box, it worked. After a while the lows dont work. Could it be an issue with the light switch on the column? If not im lost on this one and any help would be appreciated. Thanks yall.

 

Did the low beams both stop working at the same time? Can you jumper / power then to see if they’re still working at the fuse panel?

 

Yea, they both stopped at the same time. I found this box under the dash which I dont think is OEM, it has some corrosion on it. This truck has a hookup for what im assuming was a car phone. It has a box in the back window with the brand “United States Cellular” on it. Or it could be from the alarm system installed as it has a “siren” wire option on it.I havent tried the jumping. I dont have any test leads or anything with clamps to power them. I know they work because it’s happend before so its not like the bulbs went out I dont think. Actually I looked it up, the model number comes back to a alarm. The alarm was pulled out but the wiring is still in it. One of the wires in the connector has a “light” wire.

 

Sounds like a ground issue to me.
You need to check powers and grounds at the socket to see what is missing.

 

FWIW, the powers are the same.
The grounds are different. They "change" in the headlight switch.

 

I clamped a wire into the ground section in the headlight box, and grounded it to a bolt, high beams come on with the low beams now and switching to high doesnt change anything. Then both the bulbs went super dim so im guessing I somehow blew the bulbs up or something. But no low beams at all. Edit: now the drivers side bulb comes on all the way. But the passenger still is super dim, which I did accidentally bump the power terminal on that one so that would make sense.

 

Yeah, I don’t know what you mean?
There are 2 sets of ground wires at the bulb.
1 ground is used for High.
The other is for Low.
Both the High and Low use the same power.

I don’t know how you grounded the lights in your test.
But it sounds like you grounded both sets of ground wires.
That will make both filaments in the bulb come on. And could cause it to over heat and damage the bulb.

 

At the passengers side head light you should have a red/white wire.
That is power.

You will also have a red/yellow and a red/green.
Those are grounds. One is for low one is for high.
Use a voltage meter and see if you missing the ground on low.

 

I did ground the bulb with a piece of wire, but only one wire per bulb and not 2 at the same time. I swapped the bulbs around and both have high beam power but in the other side it just has that super dim light. I looked up a picture and it showed the 3 prongs having a high and low power with only one ground.

 

So I took my multimeter and clamped one end to the positive, and touched both grounds, both read about 12ish volts.

 

I’m not sure why no one has mentioned this yet. Your bulbs are dual filament, so each ground wire will activate each filament separately. If you pull back on the headlight stalk, it will ground both wires, illuminating both the high and low beam filament at the same time. Try this at night and see if the lights get brighter. If they do, then your low beams work, if they don’t, obviously they don’t work.

When the high beams are activated, power travels through the low beam filament to the high beam indicator on the dash. The fact that yours illuminates means that the low beam filament is still connected (not broken). Or you have something wired incorrectly.

 

im pretty sure it has something to do with the ground for the low beam. I took a wire and touched it to the low ground on the light and touched it to the battery ground and the low beam came on and the high beam indicator in the dash went out, if I remove it the lights go out and the high beam indicator comes back on. Now its just finding out where it is.

 

The wiring for all the headlights where pretty bad, when I bought the truck there were offroad lights wired into the high beam lights and it looked like this. Not sure if it has anything to do with it but im gonna cut them and re wire them with butt connectors but not with both wires for one side.

 

This is what my 98 looked like when I bought it. All wiring from an aftermarket alarm and random lights.



Took it out and went back to original wiring.



You will save a lot of time by doing all that now.

 

I definitely am going to eventually. I have to currently commute 2 and a 1/2 hours everyday so im worn out by the time im home. Either gonna get another car or something, or gonna get some job closer. More time to do fun truck stuff. This is kinda a photo of all the stuff under mine