Headlights Suddenly Stopped Working

I am attempting to troubleshoot an issue with my 2004 Tacoma where both high and low beam headlights stopped working simultaneously. I have yet to pull out the meter (nor have I been able to find a diagram or troubleshooting procedure) to try and isolate the problem, but rather have tried a few basic items. Both headlight filaments on each bulb appeared intact, but I replaced them just in case. I have also replaced the headlight relay under the hood.

At this point, I'd like to find some information on troubleshooting the switch itself, to see if that may be the problem rather than just buying one and replacing it, as it is more costly than the bulbs and relay.

I do note that the running lights do not come on either (but the tail lights and relay work fine). The high-beam indicator also does not come on, so I suspect power is not making it to the main relay.

Are there any other components, to anyone's knowledge, other than the switch and the wiring on this?

I definitely appreciate any help that could be provided. I've searched through threads on this forum, and apologize in advance if someone has already posted something noteworthy that could be of use.

 

Wiggle some wires

 

You do not mention that you checked any fuses.

 

EDIT: I checked all fuses, both inside the cabin and under the hood, to include headlight related fuses, and others.

 

Check your ground wires

 

Glad to check any grounds and wiggle any wires but don't necessarily know where these touch-points are (I've wiggled wires while installing new bulbs). Does anyone possibly have the associated diagram for reference?

 

Have some one put a finger on the headlight relay. It should click when the headlights are turned on. If it does not click, the power falure is between the relay and the on/off switch.

 

Is your Tacoma equipped with Daytime Running Lights (headlights coming on automatically when you start the engine) or not? There is a huge difference in the headlight circuit for trucks with DRL and without DRL.

 

No DRM. They have to be turned on and off automatically.

The headlight relay does not click when the switch is used.

 

See if you are getting power at the fuse.

 

No DRL - cool, so this makes it easier. The last question, thing to test: Pull the headlight switch for "flash". See if relay is clicking and high beams come on. I suspect they will not, but that test is needed to eliminate BODY ECU problem.

 

You are correct that the relay does not engage when flashing from high to low.

I also checked and am not getting 12 volts at the fuses (with the exception of the tail light fuse).

 

I was asking on "flash" feature that would tur on high beams regardless is lights are on or off. As you can see on the diagram below, there are no fuses before head relay:



The "Flash" feature turns on head relay (the clicking thing) bypassing any fuses and BODY ECU. So if by pulling the light stalk (to Flash) and relay does not click it is the issue between battery, relay, headlight switch or grounding of that switch. If that works, but turning the stalk by two clicks (from off to head) and relay does not click, then possibly ECU is blocking or contact 13 on the switch is bad (or the switch itself).

 

Very useful, thanks for the diagram.

I confirmed that the Head relay does not click in either scenario.

Neither pulling the stalk (bypassing the body ECU), nor placing into the Head position produces the desired effect of engaging the relay (no clicking sound).

 

I’m pulling this thread back up because it seems most relevant to work from. I suddenly have NO high beams or high beam indicator! My Tacoma is a 2004 single cab without daytime running lights. The pickup went to the dealer for its 20 year service yesterday. They left it on high beams, today I stopped in front of a business and saw parking lights only. A little playing around and I realize I have normal low beams but no high beams.

The flash pull works but no high beam indicator. The low beams work normally. No high beams. I can drive for now but want this fixed asap. Any ideas on the fault?

 

Well... I found the problem and I'm gonna blame the nut behind the steering wheel. My Tacoma is low on miles and pretty much stays under street lights around the I-5 corridor between I-90 in King county and Hwy 2 in Snohomish county. Apparently I allowed BOTH of my low beam headlights to burn out without noticing. If you look at the schematic above, shared by RysiuM, you will notice that if both low beams are burned out the high beams will still work, but the high beam dash light will not. I ordered a couple Bosch 9003LL (long life) bulbs to replace them.