coolant temp switch or fan relay are bad.
Bad switch or wiring problem.
Not 100% sure about the Toyota truck, but I had that same problem with a late 90's Chevy. Turned out to be the clutch fan ($25 part) after I had replaced almost everything in the cooling system.
Is the selenoid getting power when the switch is turned to the start position? If yes, it's not a switch problem. Is power coming THROUGH the switch and to the starter when the key is turned to start? If not, it's a selenoid problem. If yes, it's a starter problem.
Turn the stupid headlight switch off. DeeDeeDee I have the same problem with my 87 Camry. You need to change the stop light switch.
A short circuit in the wiring or in the switch.
I had this problem in my 1991 Suburban. It turned out being the A/C, Vent, Heater switch having burned contacts. Had the switch replaced and smell went away.
Perhaps you turned on the interior lights when you were adjusting the headlights?
I had this problem a month ago. After I disconnected the battery to clean it, the alam went off when it was reconnected. The owner manual said it would be turned off when the van is unlocked with the key or remote control. This did not work. If you have a valet switch (a small toggle switch under the dash) you place the key in ACC or ON and turn the switch to the opposite position. Hope that helps.
An old/worn/faulty light switch, or the wires connected to the switch are loose. Replace the switch ASAP.
Tailights or stoplights? Stop lights could be a defective stop light switch Tailights could be either parking lights are left on or a defective switch
Most cooling fans will stay on for a minute or so after turning off the car in warm weather. If they stay on past a minute or so, then there is a problem.
Overheating at the Fan Switch merges contacts inside. Replace the switch and the problem will go away.