Need help diagnosing fuse and relay issues on my 04 Tundra

So, I need another tech to help me out with my 2004 Tundra. I’m trying to diagnose some fuse and relay issues with my headlights and gauges. The last tech I talked to dipped out on me because I used profanity (oops), so here I am. The issue seems isolated to just the headlights and gauges, nothing else acting up. Anyone got some insight on this?

When you say isolated, you mean like no other electrical issues at all? No flickering or weird behavior anywhere else?

LyamGenesis said:
When you say isolated, you mean like no other electrical issues at all? No flickering or weird behavior anywhere else?

Yeah, nothing else. Just headlights and gauges. Everything else seems fine.

LyamGenesis said:
When you say isolated, you mean like no other electrical issues at all? No flickering or weird behavior anywhere else?

Have you checked the headlight relay? It’s controlled by both the headlight switch and the CPU. If the CPU detects a problem, it might be preventing the lights from working.

Did your theft deterrent system activate recently? If so, it can cause the headlights to flash every 0.4 seconds for about 60 seconds.

Keller said:
Did your theft deterrent system activate recently? If so, it can cause the headlights to flash every 0.4 seconds for about 60 seconds.

Nah, nothing like that. It’s not flashing, just straight-up not working.

I’d start with checking the fuse box for any blown fuses related to the headlights and gauges. Sometimes it’s something simple.

Taran said:
I’d start with checking the fuse box for any blown fuses related to the headlights and gauges. Sometimes it’s something simple.

Yeah, I checked the fuses and they look fine. That’s why I’m thinking it’s the relay or something else.

FYI, if your TVIP system (theft deterrent) is acting up, it could be interfering with your headlight relay. Have you tried unlocking the doors with the key or the wireless lock system?

Audrey said:
FYI, if your TVIP system (theft deterrent) is acting up, it could be interfering with your headlight relay. Have you tried unlocking the doors with the key or the wireless lock system?

I haven’t tried that, but I’ll give it a shot just to rule it out.

If it’s just the headlights and gauges, there could be a shared ground or wiring issue somewhere. Have you looked at the wiring diagram?

Elliot said:
If it’s just the headlights and gauges, there could be a shared ground or wiring issue somewhere. Have you looked at the wiring diagram?

Nope, but that’s a good call. I’ll try to dig up the wiring diagram and check for any shared connections.